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1,013 Posts
Discussion Starter #1 (Edited)
Hi everyone, this thread was started on clublexus in the sc300/400 section but it also applies to n/a supras so I copied it here.
This thread might be updated less frequently than the other one, so if something isn't working or missing also check the original thread.

This guide is for use of factory 2JZGTE ecu's on NA-T with coil on plug conversion.
I made some diagrams to help people understand whats needed for the TT ecu mod.
This thread shows wiring for vvti coilpacks, which are newer generation coils found on the 1jzgte vvti, 2jzge vvti and 2jzgte vvti.
The bonus is that these coils will fit under the stock 2jzge intake manifold without modification and they are excellent coils.

*Edit* Just recently figured out how to do this mod without the coilpacks and keeping the stock distributor and coil.
This cuts down on quite a bit of wiring and you can still upgrade to coilpacks whenever you want.
See post 4 for that, I am going to leave post 1 with the coilpack version of the mod since its the complete mod.

This thread has grown rather large with a lot of info spread out on different pages, so try using a google search + tt ecu mod to try and find what you are looking for. If you cannot find it or have a old/new question, just post it at the end of the thread as its just an ongoing discussion and tech help at this point, its alright even if its been asked before it can be a little challenging the first time you do the mod.

So, Onto the good stuff. From here you must make a choice that will affect the parts you need to perform the mod.
There are 2 choices.. Choose your destiny... USDM 2JZGTE ECU or JDM 2JZGTE ECU

simple right..? not really but majority should just go ahead and use the JDM ecu which is the proven setup and works with most common na-t setups.

all 2jzge and 2jzgte non-vvti have the same ecu connector so that is the starting point for this mod, we can plug in several different ecu's.

For 2JZ-GE's that are 92-95, I recommend using a JDM ecu 100%. its map sensor based and takes the least amount of messing with to get it to run well.

For 2JZ-GE's that are 96+ non vvti, I still recommend using the JDM ecu as its map sesnor based and runs the best out of the box. The wiring is a little different you must take power and ground from the tps as the 96+ maf (12v) is different than the 92-95 maf (5v).
- IF you want to try and have an obd2 compliant ecu then there is sort of an advantage to using the USDM ecu as you can keep odb2 working. The wiring is a little different we don't reuse the maf wires for the map so see post 4 for that. *DISCLAIMER* setting up the US GTE ecu's with a maf can be quite a pain to get them to run without misfire codes. only do this if you must have emissions, and consider getting a VPC or map ecu to delete the maf. Even a vpc seems to set off misfire codes otherwise the cars seem to run ok. not sure anyones tried the map ecu yet.

If you are 98+ vvti, then you have to use a JDM VVTI 2jzgte ecu but odb2 port will not work. The VVTI 2jzgte was never offered in US.
The 2jzgte vvti and 2jzge vvti have the same ecu connector (I think), but its not the same as non vvti connector, so you are stuck with this ecu but the good news is you already have the right coilpacks ignitor and most of the wiring, and once done it will control vvti like a gte would, will probably need a gte maf to be swapped in place of stock maf and a map sensor added (2jz) to keep ecu happy. Don't think anyone has done this so let us know if you have more info on it.

Now that we touched on the year ranges and an idea of what ecu you should look to use, I want to mention about transmissions.
The tt ecu mod does not control the torque converter lockup on the GE transmissions. this function does not work.
The GE trans will shift through all the gears, it just won't lock/unlock the torque converter.
If this is important to you for long drives, cruising on the highway etc.. then you need to look into swapping in a TT auto and wiring it up, or swapping to a manual transmission, or possibly investing in a beefy trans cooler but I dont know if that will be enough (probably a good idea either way though).

So, this write up is focused on 92-95 using the JDM ecu and VVTI coils, that is what most will end up using as it is just map sensor based.
Skip to post 4 for info on using a USDM ecu 96-97 (you will need a TT maf and TT map, and get 550cc injectors instead of the 440cc)
See post 4 for wiring up the stock coil/distributor instead of a vvti coils (still need a ds62 ignitor though)
See post 4 for wiring up TT ignitor/coils instead of a vvti ignitor/coils (must have a Font Facing Intake Manifold)
See post 4 for wiring up 1ZZ/2ZZ coils instead of a vvti ignitor/coils (must have a Font Facing Intake Manifold)
See post 4 for wiring up GM LQ9 coils and for using the stock ignitor/coil (both currently require an IGF simulator/faker).

Parts for JDM ECU:
TT ecu: Jdm Aristo or Supra ecu (aristo is more common and always auto; supra has auto and manual ecu's)
injectors: 440cc (stock size and plug and play), or you can run up to 550cc reliably with a fuel controller
airflow: TT Map sensor(2.3 bar) + Intake temp sensor IAT (universal is fine)
coil on plugs: For vvti coils you need a ds62 ignitor (toyota version) (or dh61 lexus version).
Heated o2 sensor works best but even the stock non-heated one works but a little longer to warm up when cold.

You will also need 5 spare ecu pins to do the mod with vvti coils (recommended), 8 for doing mod with gte coils.
you can get these off a spare harness or from another member or online as well as at Toyota.

STEP 1: Install Map and IAT
Install Stock TT MAP sensor and IAT as per diagram below, if your wire colors are different go by pin location.
Map sensor can be 1jz or 2jz, thats about it. IAT can be from the 1jz, 2jz, GM, or a universal unit (im using an aem one).
this is the wiring for the jdm ecu, which reuses all your old maf wires to connect your new map and IAT to.
note you move the old maf signal wire pin (B66) to the map signal wire spot (B62) at the ecu plug
do not forget or you will have no map signal

Just a heads up, when installing the map, get all your wires right and ready in the connector before plugging the map sensor in, if it isn't right unplug the map and do the wiring till you get it right. Don't make connections while the map is connected or you can hurt the map or worse the ecu 5V driver and then you could need a new ecu.

Step 2: Install injectors
stock size is 440cc, I suggest most people start here and it will support 400hp. good for at least a bar of boost on most medium size turbos.
550's will start and drive around but will run very rich. Most wash out the spark in boost when running 550's and no piggyback.
So a safc is recommended if you go 550cc, but if you go larger like 660cc safc is definitely needed as it won't run right.

You are looking for top feed injectors (unlike gte side feed injectors), and you are looking for high impedance.
also they are specifically import size ("Denso") or 11mm, if you see domestic or 14mm injectors those will not fit the stock fuel rail.
7mgte injectors drop in but are low impedance and require a 7m or JZ resistor pack, and usually an injector cleaning.
Many aftermarket 440cc's are high impedance and do not need a resistor pack (Like some RC's, Delphi) which are the best/easiest route.
Also there are alot of options online for remanufactured injectors that seem to be a good route to try. search for "2jzge injectors".

*I am going to try and update this with known injectors that work as people report them back to me.
I have heard these are the proper RC 440cc: RC SL4-440 but it is not confirmed which part number has the right type for the lower runner, will update when it is.
Alot of injectors like these will have EV1 connectors and you need to change your injector clips to EV1 style (or use plug and play adapters):
There are some injectors that have the round denso clips (like stock) like remanufactured but are easier cause they are drop in with not adapters needed.
consider though that with a ffim, the adapter gives you extra length to tuck your harness under the manifold without having to break out the soldering iron.
If you do break out the soldering iron to change clips, make your wires longer than stock it will help alot when you put on a FFIM you wont need to rewire at all

If you are 96+ or using a 96+ lower runner, note that the odb2 lower runner uses a different style of injectors that look similar to the IS300 injectors which have 2 orings, a small one on the bottom and a large one right above it. ODB1 injectors are the common ones that just have the 1 oring at the bottom. please note they are not the same generally speaking. If you have an odb2 runner you can get away with using obd1 injectors, as the main larger oring will seal the top part even though its not the perfect size. the air assist hose stuff won't work but no one cares about that usually.
other options are to try IS300 injectors which are becoming available now in larger sizes (I am not 100% sure they will fit they just look the same notice I wrote try), or you can change your lower runner to a odb1 lower runner and use the odb1 injectors, and yes the odb2 upper will bolt to the odb1 lower runner just fine. you can also use a obd1 throttle body and that will get rid of the other size of the air assist hose. again you can just use the obd1 injectors it turns out on your obd2 runner and block the air hoses from the throttle body, at least on normal boost applications.

1,013 Posts
Discussion Starter #2
Step 3: Install Coil on plug ignition system
I recommend using the vvti coils and ignitor setup, which is all around better than gte coils and fits under the stock intake manifold.
See the diagram for the vvti wiring below.
You can run the vvti coils with either the lexus ignitor (DH61) or a toyota ignitor (DS62) as they both are the same ignitor.
I recommend finding the DS62 because they are widely available online and you can usually get the plug with some wires on it all for around ~$30, and the plug is really usefull as plug alone cost similar at toyota, and the dh61 alone will be several times more than this price and I have never seen one with the plug cause no one in their right mind will cut a vvti harness so you can have the plug and wires. You can get these parts at Toyota also if you have one without the plug but its pricey for just a connector and some wires.

I put steps 2 and 3 together, its because when doing the injectors you will have the stock intake manifold apart, and is a good time to drop the coils in as you will have to remove at least to the throttle body to get the vvti coils dropped in, like a regular spark plug change. Also the old metal spark plug holder thing needs to come out of the plug valley so your coilpacks can sit right and its held on by the inside valve cover bolts.

Step 4: Fire her up and set your base timing with a timing light.
Follow the timing check procedure in any of the manuals.

You jumper the diagnostic pins (TE1 and E1), and set the base timing by rotating the distributor.

You should always hear a VERY NOTICEABLE change in how the motor is running/sounding when you put the jumper in to set the base timing.
If you don't hear anything change, the tps is not in the right position and it wont let you change base timing cause it thinks you are revving some.
See this very helpful post by HiPSI showing how to adjust the tps when ecu won't let you set base timing.

Once you got it changing sound when you put in the jumper, you are ready to initially set the base timing.
I recommend starting low like 6-8 degrees I like mine best @ 8 and I have a TT headgasket only.
After it is warmed up fully hot double check and adjust your base timing if necessary. If you set it cold before then it may be different now.

stock gte base timing is 10 degrees but the higher your compression is the less base timing you can run or you may pick up knock.
For Example: If you have gte compression (8.5), set it to 10. if you have 9.x:1 compression, set it to 8. If you have stock compression, you probably want to try 6-8.
Play with the advance at your own risk but remember lower is safer.
Always set your base timing when changing ecu's, if you happen to be too advanced you can damage your motor

Step 5: O2 sensor
The stock o2 sensor technically will work the JDM ecu and you only need one o2 sensor instead of 2 or 3 you may have already.
some SC's come with 1 wires sensors (non heated) and 4 wire sensors (heated- found on obd2 or all cali spec).

If you have a 4 wire then you have the right kind already, make sure the one that goes to ecu pin B48 is the one you are using, and that the heater for that one goes to B71.
If your downpipe doesn't take the bolt on kind you have you can just get a 4 wire sensor described below that is a scew in type, and redo the wiring on your plug, no need to add wires to the ecu since your car came with heated you are ahead of the curve.

If you have the 1 wire, then you can either use that and live with burning a little extra fuel on startup till the car warms, or get a 4 wire sensor and wire it up to the ecu. alot of times you want a new sensor because of a screw in type for most downpipes and well unless you just replaced yours its a good idea to get a new o2 sensor on these ecu's especially since you are turbo now.
You can also just get a 1 wire screw in type and put it in and call it a day, but if you want your o2 to come on within 20 seconds or so of starting the car, then you need to add the heater wires.

The sensor I use is a Denso 234-4309 universal 4 wire sensor (you can get great deals on these online usually under $35).
To wire a 1 wire to a 4 wire:
One black wire goes to ecu pin B71 (heater pin ecu uses to turn heater on).
Other black wire goes to 12v pin (black/red wire at ecu or in engine bay, power for the heater).
The White wire to a chassis ground (Its a ground don't ask me what its for just ground it already).
The blue wire goes to ecu pin B48 or just connect to original signal wire (the signal wire its pretty self explanatory).

This is what it looks like on a car that comes with a 4 wire o2 stock for reference (95 supra TT USDM).
Note that the heater wire on the JDM ecu is B71 as said above. It is not the one in the picture below the one below is just an example.

Step 6: A/C Relay (when using Aristo ecu, Supra ecu not needed).
If you are using an aristo ecu here is the a/c fix, see post #29
Basically GE Hvac unit sends send ground to the ecu, and aristo ecu wants a power signal, so this relay fixes that by sending power to the aristo ecu when it gets the ground from the GE Hvac unit.

Step 7: torque converter lockup fix (Only for automatic models, if you are manual skip this step)
There was a theoretical relay fix here on post 1619 that was tried but it does not work, so don't expect this function to work.
I would suggest swapping to a manual transmission and not worrying about any of this stuff as mainly the stock auto is delicate,.
You can go with a GTE auto and add all the extra wiring (I dont know what exactly you will have to look up the wires or easier way is grab a gte harness and unwrap it and borrow all those wires).

*Edit* I did some reading over at clubna-t in this thread
Basically it says you can swap the valvebody of an GE auto onto a GTE auto so you can have a GTE auto controlled by the GE ecu (what we want but backwards). Well that got me thinking its probably possible to then install the GTE valvebody onto the GE transmission and control it with our GTE ecu. So if someone wants to try it just need a gte trans or valvebody, and then swap it onto your stock trans. the wiring would also need to be added for the extra solenoids like if you were swapping the whole gte auto and moving a pin or 2 around at the ecu.

I would still think its better to swap in the gte auto and wire it up, than installing the valvebody on the GE transmission because the gte transmission can hold more power and more reliably.

Step 8: Re-Plumb ACIS butterfly directly to intake manifold (recommended with stock intake manifold)
The TT ecu has different VSV's than the GE ecu and does not control ACIS correctly when doing the mod.
This results in sluggish spool and down low performance basically getting no benefit from the GE intake manifold design.
Good news is connecting the ACIS valve as shown in the post below will give you a large increase in spool compared to leaving it disconnected.
In vacuum you get long runners all the time now for extra torque/spool, and when you get into boost it goes to short runner which is better for top end HP (when the engine needs the most air it can pull through both sides of the Y in short runner as opposed to one side in long runner).
Think of it like a car having long runners all the time, and short runners in boost. the end result is very good for performance.
see post 1095

If you have removed all those hardlines, simply run a vac line from intake manifold to the butterfly like you would connect a bov or boost gauge.
Connecting the 2 hardpipes shown above achieves that by bypassing the canister and connecting the butterfly to the intake directly.

Step 9: Tach mod to get tachometer reading again with new ignitor
the 3 channel (vvti) and 6 channel (gte) ignitors put out a different tach signal than the stock 1 channel ignitor (distributor).
to get it working again remove the cluster and you need to jump a resistor with a short piece of wire (bypassing it).
easiest is to just solder each side of the wire to each of the legs of the resistor going into the board (you don't have to remove resistor in case you ever want to go back just cut wire).

its the same thing you would do if you were doing a gte swap.
jump the R109 resistor on 92-94 clusters, and the R73 resistor on 95-96 clusters.
for the newer gauge clusters 97 .. jump resistor R2 (Thanks for the info Gerrb!)

Step 10: go out and actually enjoy your na-t for a change without battling the stock ecu

I have tested it out personally, and it runs great. :thumbup:
cheap engine management for 400hp with the 440cc injectors, basically how a stock supra drives with a single on it.
throw on a piggyback and larger injectors after you get it all sorted and you can make even more power.

The best part with na-t is that the distributor can be rotated, so you can actually change your base timing with the gte ecu.
If you run really large injectors and your piggyback is advancing your timing, you can actually dial back your base timing with the distributor/CPS.
YOU CANT DO THAT ON A GTE MOTOR!!! an extra feature that may prove to be very helpful in the future.

1,013 Posts
Discussion Starter #3 (Edited)
**edit** I wanted to link this great thread on using a TT ecu w/TT coilpacks

I have found it to run really well with the stock map sensor and 440cc injectors. thats a great baseline to start from.
The TT coilopacks and ignitor works with the TT ecu, The vvti coilpacks and ignitor works as well, I have verified both.
I have not run the distributor in its stock form with the stock ignitor and coil, and some people are having ignitor issues trying out the stock setup. The gte ecu with proper coils should now be the starting point for na-t management. the ge ecu cannot even compare to how the gte ecu drives.
My car drives like a stock lexus again, with about double the power.

Short vid of it running on the GTE coils and Ignitor, before i installed the vvti coils and ignitor.
Note: if you do not have a front facing intake manifold (FFIM), you cannot run TT coils and ignitor, they wont fit under the stock intake.
This is another reason I only recommend the vvti coils now.
SC300 Na-T Running on a JDM 2JZ-GTE ECU - YouTube

Another short vid of it running on the vvti coils and ignitor (my preferred/current setup).
2JZGE Na-t Revving using Aristo ecu - YouTube

Here is what the ecu connector looks like and the places of interest to us (GE and GTE have same connector).

This shows how you wire up the coils and also move the wire for the old maf sensor to the new MAP sensor spot (ODB1 only).

Remember the 3 coils have to go in a certain order as shown in the picture (this is the least confusing arrangement trust me):
Coil 1 sits on cylinder 6 (and has a lead wire running to cylinder 1 not shown)
Coil 3 sits on cylinder 4 (and has a lead wire running to cylinder 3 not shown)
Coil 2 sits on cylinder 2 (and has a lead wire running to cylinder 5 not shown)

general guideline of what to do for the ignitor wiring:
your wire colors may be different but the pin locations are always the same on these ignitors.
look at this diagram from a 95 supra for pin locations (I don't have the SC one right now).
the power wire should always be black/orange, and the IGF is always red/yellow... the tach wire is usually black or black white..
the rest well the vary from year to year

First remove all the pins/wires out from the old ignitor plug, and then insert them into the new ds62 ignitor plug as shown in the diagram, this includes +B, tach, IGT1, IGF.
you only run 2 new wires from the ecu and that is IGT2 and IGT3.
Then you add a ground wire and ground it to chassis ground or even battery ground.
For the 4 wires to the coils, you run the 3 signal wires (coils 1-3) to the new coils, and for the +B for the coil you have to splice off the +B wire you just moved over from the old ignitor.

The old coil wire that goes from the stock ignitor to the stock coil is not shown in the diagram above because normally its not used as it goes to the wrong place, but its the 5th wire connected to the old ignitor that's not the 4 shown above. If you were to rewire your harness you could potentially move and reuse this wire, but its easier to just forget about it, and get a mk3 coilpack harness and extend those 4 wires from the coils to the ignitor, as it already has the right clips on it and everything, its just short some.

here is the wiring of the plug for the TT map sensor (courtesy of 8052JZ)

this is the wire description for the maf plug on the diagram below.
pin 1 is brown: Sensor ground for MAP and IAT (not to be confused with a regular ground. 5V sensors have their own ground pin on the ecu)
pin 2 is yellow/black: IAT signal wire
pin 3 is yellow/green: MAF/MAP signal (remember to move pin to b62 for JDM version of the mod)
pin 4 is blue/red : +5v (blue/red is always +5v not to be confused with +12v used on the newer maf's like the gte maf)
pin 5 is brown: another ground (I generally use the other ground above and leave this one alone)



1,013 Posts
Discussion Starter #4 (Edited)
The mod with vvti coilpacks is above in posts 1-3.
This section is for covering other versions of the modification, like if you would like to use the GTE ecu but keep the stock coil and distributor, see stock coil usage below.
This section also covers using the USDM ecu, and also how to use different coils.

Stock coil usage (Requires DS62 ignitor)
The stock ignitor is not compatible with the gte ecu. the difference is the older ignitors returned an old style IGF signal to the ecu which it needs to stay running, and the newer coilpacks ecu's they changed the IGF to a current type signal so the engine starts and then dies.

What you do is replace the stock ignitor with the DS62 ignitor, and do not add the 2 new wires coming from the ecu.
You just pin up the old wires into the right spots on the new connector all for coil 1, so coil 2-3 and IGT 2-3 will be blank/unused on the new ignitor. Basically we are only using 1 channel of the 3 channels on the new ignitor, and it should work fine and return the right IGF to the ecu.

check out these very helpful posts by HiPSI with pictures for reference on what the jumper looks like (Thanks!!!)

From Aaron's (aswilley) thread thanks for the updated diagram (do note he is using jdm ecu with stock coil on a 97 harness)
this shows the colors on a 97 harness which may look different than your or above.

Alot of people have been asking about using the USDM ecu, especially when then are odb2 non-vvti it is usefull to use the USDM ecu so you can keep odb2 and all emissions in tact like a factory gte would, believe it or not the 2JZGE has the identical emissions components and sensors. You must use 550cc injectors, and Note the USDM ecu uses both a maf and map sensor

Here is how you wire that up for the USDM ecu on a 96-97 2JZGE harness.
wire up the coilpacks and ignitor as shown for the JDM ecu mod above. it is the same.
The stock maf sensor will be swapped with a TT unit, and the maf sensor plug will not be modified at all since 96-97 uses a hotwire 12V maf and the GTE maf is a 12v Hotwire maf with the exact same plug, do not cut the maf connector off like the JDM mod version above since its already plug and play. Since the USDM ecu uses both a maf and a map, we will run new wires for the map sensor since the maf is being kept. (Note for 96 harness users: on a 97 GE harness the maf ground wire 28 and is the same as a GTE pin, but it may be pin 30 on the 96 GE harness, so if you have a 96 you may have to move pin 30 to 28 for the maf to work correctly).

Just an update, for those using the US maf with a single turbo, it doesn't run that well until you delete the maf by using either a VPC or a map ecu type unit. its well documented on supraforums.
you can try the maf but I wont be helping troublshoot stuff that doesn't work right, plan to convert to map on the USDM ecu. its worth it if you have to keep obd2, otherwise just use a JDM ecu.
ultimately it should be a 2jz map sensor wired in for the US map sensor, and for the US maf sensor you have a map ecu or vpc wired to that.
so technically you have 2 map sensors, but the only one that is used for fueling on a US ecu is the one which was converted from being a maf.

For the Map sensor you run a new signal wire from the ecu from B62 to the map sensor signal on the connector and for the power and ground for the MAP sensor you can tap into the TPS power and special sensor ground, the TPS and MAP sensor power wires are the same blue/red color wire on all the harnesses this is the ecu 5V wire. Do not try to tap the power off the maf wires for the Map sensor as the maf is 12v and will not work on the map sensor, could even mess it up. Do not try and use the ground of the maf as this is a 12v or standard ground the map sensor uses the special sensor ground, again tps sensor is easiest place to pick up the power and ground for these then you only need to run 1 wire to the engine bay to the map sensor. This is my recommended method.

Refer to Aaron's 97 build thread that shows a new diagram for wiring the map sensor to the IAT for 96+ models.
Do note he used a JDM ecu but his diagram still shows the wiring for the map sensor power and ground that is needed on 96+ harnesses.
If you are on US ecu, the map signal will likely be running a new wire for the map signal, not reusing 62 from the maf as the US still needs that wire.
Thanks again for the updated diagram!!

There is no separate IAT (air intake sensor) like the jdm ecu has, because on the US setup it is built into the maf (see wire for THA) it is already wired so you can skip over IAT related stuff.

I would use the vvti coil setup above, but if you need to use sequential coils or just the regular gte coils, here is the stock wiring for the TT coilpacks. Again note: THEY DO NOT FIT UNDER THE STOCK GE INTAKE. YOU MUST HAVE A FFIM.
This time you will need to run 5 new wires instead of just the 2 needed for vvti coils, and just like above you reuse 57 and 58 (IGT1 and IGF) from the old ignitor as they are already there stock so you are just adding 52-56 and running to TT ignitor.

You wire them like the gte coils above, except the wires from the ecu go straight to the coils skipping the ignitor.
Each coil will one also get its own power wire and ground wire since they have internal ignitors.
Each coil returns its own IGF signal, so you must connect all 6 wires together and feed them back to the 1 stock IGF wire to keep the engine happy and running.

You wire them like the gte coils above, except the wires from the ecu go straight to the coils skipping the ignitor.
Each coil will one also get its own power wire and ground wire since they have internal ignitors.
The GM coils do not return an IGF signal to the ecu, so to keep the engine running you will need an IGF Simulator/faker or find some way to keep the factory ignitor in the mix. If you know of another method that works let me know.

173 Posts
Very well done sir!!

358 Posts
There it is! I can breath easy now, thought you deleted it forever!

This truly is an awesome mod for NA guys. Ali has done an amazing job working the kinks out himself and he is willing to help / answer any question big or small.

My car runs like a stock supra, + 16psi through a PTE6265.

1,013 Posts
Discussion Starter #8
Thanks I actually put it back up over there also I decided everyone should still have access to it after all.
Ill leave it here also for those who are interested in it the ignitor colors might be a little different on an n/a supra but its very easy to figure out from the manual.

33 Posts
For a NA/T Sc, the stock ECU is evil and must be punished and banished. :die:
This is a truly brilliant, heavily tested mod and I am running it as well. My car runs GREAT!

102 Posts
Hey Ali, first I would like to say thank you for all the time and work you have put into figuring out and documenting this mod.

I just swapped a JDM 6spd tt ecu into my na supra using the stock distributor with the ds62 igniter. Also running the stock 02 sensor and have verified that it is going to the correct pin on the ecu plug.

I am having an issue with the car not running right. The car starts right up, but my aem wideband reads very lean at 16 - 17. If I blip the throttle when the engine is still cold it stumbles and cuts out. As the car warms up it gets even leaner to the point where it will stall out completely just idling.

I was wondering if you could point me in the right direction for troubleshooting? My gut feeling tells me that the symptoms are that of a vacuum leak, but I haven't been able to find one yet. I have deleted all of the emissions stuff and have used all new vacuum lines for everything. I have also triple checked that the intake manifold is all bolted up tight with new gaskets. The only other place I can think of would be the lower injector grommets.

Some info on the car:

It was running perfect before I did the swap

I am using a JDM TT 6spd ecu, and also have an aristo ecu, same problem persists with either one.

I have wrx injectors that have all been cleaned and flow tested at 440cc +/- 3cc's

I am still on the stock fuel pump, but didn't think that would be an issue(especially at idle) as the car is still na.

I'm using the stock JDM map and iat sensors

I would greatly appreciate any insight you might have, and thanks again for all the work you've done.

1,013 Posts
Discussion Starter #11 (Edited)
a vacuum leak on a map sensor ecu wont lean you out, only on a maf sensor car.
with a map sensor the extra air would just raise the idle and the ecu would add more fuel to match from the map sensor, cause map sensors read whats in the intake manifold so they run decently well even with leaks.

I think your injectors might just be too small. are you sure they are 440's and not 420's.
it really sounds like there just isn't enough fuel if the idle rpm is normalish and its running decent until you tap it.
I have had that same experience with injecting too little fuel when tuning via the map ecu.

normally with the 440's I had the car will want to first start and run in the 11 afr range until it starts to warm up and then it gets leaner.
when you blip the throttle it usually goes a hair leaner for a second, so why you have a cold motor sitting at 16 as soon as you blip it they generally want to stall out, well cause cold motors need a bunch more fuel than a warm motor. your problem continues as it warms up cause the coolant temp sensor is telling the ecu to inject less fuel as it gets warmer, even though the engine needs less fuel this is still bad when you didn't have enough to start with.

I think the answer is different injectors.
here I am seeing a wrx 440 next to supra injector, they don't even look the same size, how did you fit them even? did you remove the plastic spacers under the fuel rail or something?

blue subaru -440cc, 850cc uncapped
next to a supra 440
also you can tell by the shape they are different generation injectors "EV" then a number
Stock is like a EV1 (1980's - 1990's, 80's had square plug, most 90's had a round plug aka our cars) and those WRX are pretty much EV6 injectors which most cars went to in the late 90's into the 2000's. most current models use EV14 now (think ID1000's).

whats important about that is different generations of "EV" injectors has different lag times.
so even though 2 injectors are the same size, the lag times being different can result in the ecu injecting different amounts of fuel.

of course yours is off by 5 AFR points which is significant not just a little, but that could be explained by the different injector size, and if they are the same size they can be explained by lag times. Ill spare you the explanation but any difference in lag times will result in more or less fuel by that exact difference in lag time.

to get an idea look at this chart
has the wrx lag times, and they are different than the EV1 variety, for example look at the Rc440's @ 13 ohms.

there is also the possibilty of a "false lean". this happens when there is so much fuel that misfire is always occuring, and the unburnt oxygen is picked up by the o2 sensor, this creates a false lean. you can generally tell cause the exhaust will smell like raw fuel in a few minutes like that, along with popping in the exhaust on accel or decel.

if you disconnect the vac line to the fuel pressure regulator, you will get an additional 8 or so psi of fuel pressure, which might make it run a whole lot better.
you can alternatively disconnect the vac line going to the map sensor which makes it read 8 psi higher than idle, which will make the ecu deliver more fuel, although it might not want to start with the map sensor like that.
either way you will get more fuel at the injectors and might clear up the issue, then you can confirm its the injectors. also the map sensor should make a change but usually when they are bad the engine doesn't want to start and idle well even at a wierd afr. dont drive around like that just as a test... lol.

102 Posts
Great info!

It sounds like I need to look at the fuel system for sure. I know the wrx injectors are rated at 420cc, but the flow chart that came with them is definitely at 440cc. I just assumed that even if they were 420cc the AFR's still wouldn't be anywhere near as far off as it is right now, but the lag time makes perfect sense. I removed the plastic spacers and the physical fit is perfect along with the plugs being the same, but it seems like they don't play well with the stock ECU.

I will try disconnecting the vac line to the FPR as you suggested to see if it helps, but it looks like I'm gonna just have to suck it up and buy the RC 440's if I want to avoid a piggyback. I do have a set of SARD 550cc EV1's from my rb20 laying around, but I would need to rewire the plugs as they have the older style square plug and I wouldn't want to run them without a piggyback.

I should have some time to play around with the car tomorrow, I'll post up the results with the vac line disconnected.

Thanks for the help, you just saved my from spending countless hours on chasing a problem that probably doesn't even exist.

1,013 Posts
Discussion Starter #13 (Edited)
yeah no problem, generally if you can get the tt ecu mod to start and idle (doesnt matter stock coil or coilpacks), then you are pretty close.

yeah the 20cc and the lag times will affect it enough, ignoring what fuel pressure each one puts out 440 at also. you could probably correct it with a fuel controller since its so close, but you will be lowering boost cut then since you are making smaller injectors work like stock = not so good, instead of larger injectors working like stock which raises boost cut = good.
also with the way lag time works the whole tune would need to be tweaked, since the difference will also be different at different pulse widths (or think rpm's/load)

if you are ever planning on going to a FFIM, just go ahead and change the clips and make the wires longer, or get the adapters on ebay that go from denso to square and just plug in, this makes it long enough to tuck the main harness under the lower runner when running a front facing intake manifold.

even if you never run a FFIM and tuck the harness, the adapters are just an easy way to work with older square plug injectors (usually ev1 bosch injectors), but yeah you will need a piggyback to compensate 550's run rich but thats what I run with a map ecu piggyback.

on my car so far I have gone from stock denso injectors and clips > RX7 ev1 inejctors and clips > ID1000 injectors and clips > ID750 injectors with same clips > Delphi? EV1 440cc injectors and clips > after that I now have 550cc Denso injectors and clips. I have now sworn off changing clips my back hurts from even thinking about it generally I will be using Denso to whatever adapters in the future as long as they are available.

Premium Member
1,276 Posts
Ali......thanks for the contribution brother!

102 Posts
So I just started the car up with the vacuum hose disconnected from the FPR and the car idles fine now even when at operating temp, still a little bit on the lean side but at least it works. The idle did seem pretty low tho, so I may have to mess around with it some more once I get the new injectors in.

I will definitely go with those adaptors to make life easy and since I do have a FFIM that will eventually make its way on the car.

It kinda sucks that I have to get new injectors, but it sucked a lot more not knowing what the problem was in the first place. Ali is the man!

Now that I know I got the wiring correct, I'll upload some pictures of what wire colors went where on my supra as the colors and locations were not all the same as the diagrams for the sc300 and it took a little playing around with a multi meter to figure it all out.

1,013 Posts
Discussion Starter #16 (Edited)
Yeah I mean at the end of the day changing injectors is not the *worst* thing, I mean when you tried the wrx ones I'm guessing you must have figured there was a chance they wouldn't work. maybe you can modify those to flow more, but getting the right injectors sounds like a much more foolproof plan.

That would be much appreciated and help alot of supra guys out if you can post some of the specifics for that. I have the 95 supra manual but haven't had time to upload any of the pages or change the main posts to be more supra specific/oriented yet.

102 Posts
Yeah, it was definitely a gamble but I sure learned a lot about injectors. I'll stick with the tried and true route on this next set.

I did stumble across this tidbit of information:

"The ECU pulse timing between the EV1 and EV6 injectors is quite different, older EV1 is 200 ms and EV6 is 50 ms response time IIRC. This mis-match in timing results in ~10-15% less fuel delivered for the same injector when used in the EV1 ECU. So a 19 lb/hr drops to 16 lb/ hr flow."

I'd be curious how EV14 injectors compare to these, as a lot of aftermarket injector companies are now using EV14 style injectors and I'm not sure they would work with the stock ECU.

I also called RC and found out that the difference between the SL4-0440 and the SL9-0440 is that the SL9 has the correct Nippon/Denso syle top and bottom for our application where as the SL4 has the Bosch style top/bottom, although they said they can modify the SL4 to work if SL9's are not available.

Looks like I will be ordering some SL9-0440's with the Denso to EV1 adapter harnesses and call it a day!

1,013 Posts
Discussion Starter #18 (Edited)
EV 14 injectors have the lowest response time of all, thats why you can idle a 3.0L motor on 2000cc injectors and have it seem almost like it was stock.
with an ev1 injector you would have to raise the idle rpm and probably remove some timing, even then it would likely want to sputter about.
EV6 is actually close to the EV14 in shape size and response times, but the ev14 is the upgrade for the EV6.

you can actually find EV14 injectors stock on lots of newer mustangs, but the sizes are all wrong without some modification.
like my 2003 gx470 had ev6 injectors and those work pretty nice. generally EV6 injectors will have a 4 hole pattern on the bottom, that atomizes the fuel much better than the EV1 style with just one hole or sometimes they put a cap on the EV1's with more holes on top of the original hole to imitate the spray but its not as good.

The EV14 has the best response time and atomization, cause it doesn't use multiple holes, it has a completely new ball and seat design.
so unlike all previous generations of injectors, this new design sprays the fuel in a CONE shape, which is freaking amazing for getting a clean burn in the cylinder.
Its also due to the new design that the response times are so low because there aren't as many things moving and it can open and close faster.

a good read on the rx7 forum if you have some spare time

thanks for the clarification on that part number so the SL9-0440 is the right one, I never called to find out.
I was running some delphis apparently that were the bosch style and I think someone turned down the top portion that goes into the rail to be thinner to fit the denso style oring on there... didn't notice when I installed them I was told they came of a supra with a top feed rail so it was plug and play, but didn't realize someone had modified them previously. was only when I pulled them out did I notice but they worked perfectly.

If you can get the right ones from the start its worth it, but also just spending that money on a safc and using the 550s is not a bad idea cause the RB has the same injector setup, so they would work and provide you with more fuel overhead. the right 440's though are literally drop in and plug and play, but probably a bit pricier but good to have if you enjoy the tt ecu mod. even if you go to 550's later you can hold on to them for another setup.

185 Posts
Oside tiger sent me this when I purchased my 440CC injectors from them. Came with the adapter clips as well.

If these are hitting over 500cc when under load, the 550cc's on this ECU is a bit much.

102 Posts
Oside tiger sent me this when I purchased my 440CC injectors from them. Came with the adapter clips as well.

If these are hitting over 500cc when under load, the 550cc's on this ECU is a bit much.
Thank you for posting this.

If you don't mind me asking, how long have you been running those injectors and how have they held up? I actually sent them an email on Thursday about buying some 440's but still haven't heard back yet.
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