Getting the most out of your stock 440 injectors / raising fuel cut boost limit

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Thread: Getting the most out of your stock 440 injectors / raising fuel cut boost limit

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    Getting the most out of your stock 440 injectors / raising fuel cut boost limit

    this summer I have been on a mission to get the most out of my ct26 / 440cc setup. I want to run around 18psi.

    440cc injectors should support this power level ~ 300-330 WHP. here is the setup I am working with

    rebuilt 7mgte / ARP studs with felpro HG
    stock low mile ct26
    3" DDP / 3" test pipe and exhaust
    2.5" hard pipes and fmic
    Maft pro piggy back running speed density (so car has MAP/intake temp sensor and NO AFM)
    walbro 255 pump


    with the above setup I was running out of fuel (fuel cut) around 12 PSI. this was after leaning out to 11.5 :1
    not close to where I wanted to be.

    that walbro needed 2 more items to wake it up

    1. bigger wiring / new relay (it was dropping 2v with stock wiring). if your going to run high pressure with a walbro (or others I suspect), you need to drive your pump with as much voltage as you can.

    2. adjustable fuel pressure regulator.

    after I added those items and jacked the rail pressure up to 50 psi.....way more fuel is there to work with. my maft-pro lets me data log, here is a comparison of before and after the above 2 mods (snapshot data @ around 4500 rpm)



    worth pointing out this mod allowed me go 11% leaner on my piggy back, effectively moving fuel cut up many PSI.

    the install :

    1. regulator mounted by battery (overflow moved)
    2. stock regulator removed, used a 12mm banjo to-6an fitting on the rail. I had a spare 12mmx1.25 banjo bolt, the blue fitting didn't include that, but was sized for 12mm honda rails/banjo's.
    3. AUX fuse box installed by brake booster. this box has 3 relays : 1- wideband 02 2- maft-pro and guage lights 3-(yellow hd siemens) new fuel pump relay

    *time will tell if this yellow 40a relay will hold up. it is activated by the stock ECU pin (grounds out coil and turns pump on) so my pump shuts off if the engine stalls / does not run when key is in ON position.

    4. new monster cable (red) from relay to trunk. new large chassis ground. deans style connector (no way I was doing all this and leaving a 30 year old oem connector in there).

    5. how I got the wiring through the access panel ...taller weatherstripping (vs cutting a hole / grommet)




    all in all I am pleased with this upgrade. the pump screams now (yes, its even louder haha) ...and runs .05 volts below battery voltage. I will keep reporting back on this post if/when I find fuel cut.
    Last edited by madisonMK3; 09-04-2018 at 08:23 AM.
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    Quote Originally Posted by suprarx7nut View Post
    Sweet data!

    Is the unit of "User Tune" a percent reduction in the air flow signal to the ECU?
    basically. its your mainscale % +- current (map based) tune.

    in the maft pro the lower the mainscale/tune the smaller the AFM signal is scaled


    had a chance to do some more tuning tonight. for some reason I decided to lower my transition point from wastegate spring only boost (6-7psi) to electronic boost control. on my setup I have a spool setting that does 100% duty cycle (wastegate sees nothing) as it spools up. with this I can make it overshoot my target boost 2-3 psi and spool up harder. found out coming into boost hard around 3500 rpm, you can hit fuel cut at much lower HZ, around 1250, 15-16 psi. but, this was super rich (9:1) as I had a (stupid)tuning error resulting in a +8 instead of a -8 for the 3400 rpm high map tune.

    so, fixed the tune up. set the electornic boost to come in at 3800-4000 and she is really running nice now. next I need to lean out the 4-5 k area and add some duty cycle to the boost setup. right now its set at 13 psi and overshoots to 15-16 and settles in.

    also much cooler air on tonight runs. 65 degrees outside. but intake temps were climbing up with the little ct screaming haha. good thing I am running 4gal premium+ 1.5 gal 110 race in the tank.

    15psi.jpg

    Last edited by madisonMK3; 09-06-2018 at 10:10 PM.

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    Quote Originally Posted by madisonMK3 View Post
    basically. its your mainscale % +- current (map based) tune.

    in the maft pro the lower the mainscale/tune the smaller the AFM signal is scaled


    had a chance to do some more tuning tonight. for some reason I decided to lower my transition point from wastegate spring only to electronic boost control. found out coming into boost hard around 3500 rpm, you can hit fuel cut at much lower HZ, around 1250, 15-16 psi. but, this was super rich (9:1) as I had a (stupid)tuning error resulting in a +8 instead of a -8 for the 3400 rpm high map tune.

    so, fixed the tune up. set the electornic boost to come in at 3800-4000 and she is really running nice now. next I need to lean out the 4-5 k area and add some duty cycle to the boost setup.

    also much cooler air on tonight runs. 65 degrees outside. but intake temps were climbing up with the little ct screaming haha. good thing I am running 4gal premium+ 1.5 gal 110 race in the tank.

    15psi.jpg

    Very cool. With my 90 the only time I hit fuel cut was right around 3500 rpm. Given what you're saying I probably could have played with the settings in the profec to start limiting boost earlier with a higher maximum allowed boost and squeezed out a little more power. Interesting.

    Does the MAFT Pro output spreadsheets worth of data? Or just the dyno-style spot results like in your screenshot? If spreadsheets with timestamps, what's the resolution on the timestamps? I'd love to see some high-res data on how the 7M handles things towards that fuel cut limit.

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    yeah the resolution is not high, a tenth of a second . but looking at the software yes you can export a csv. you can see when the fuel cut happens bc the AFR goes up / rpm drops / boost pressure drops.

    fuel_cut.JPG

    im trying to upload the csv its created but suprafours says invalid file .... :?
    Last edited by madisonMK3; 09-06-2018 at 10:43 PM.

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    Quote Originally Posted by madisonMK3 View Post
    yeah the resolution is not high, a tenth of a second . but looking at the software yes you can export a csv. you can see when the fuel cut happens bc the AFR goes up / rpm drops / boost pressure drops.

    fuel_cut.JPG

    im trying to upload the csv its created but suprafours says invalid file .... :?
    OK, gotcha. Well, if you're so inclined you can send to [email protected]. I'd love to play around with the data.

  9. #7
    Canada, Eh? Enraged's Avatar
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    Over 300rwhp is totally doable with the stock 440s. My car a few years ago:

    thhptq.jpg

    Mods: FFIM, IC & hardpipes, turbo back 3" exhaust, FPR set at stock pressure (43 psi IIRC), walbro 255, AEM v1

    Those numbers were with a massive intake leak (warped flange, forgot to flatten it after welding) and a not so great tune on a Dyno Dynamics at very close to sea level. Peak boost was 16psi at around 5600 rpm, losing boost to redline.

    As long as you don't get fuel cut, you should have no trouble making the power with your setup. Doesn't the Maft pro have a built in fuel cut eliminator?
    Last edited by Enraged; 09-07-2018 at 01:41 PM.
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    Good stuff MadisonMK3!

    A point that should be made, though - boost cut is *not* fuel cut - it kills spark not fuel.

    I believe you'll have no issues making ~350whp on 440's with your supporting mods, but your limitation will be the stock CT26. The compressor wheel is just so damn tiny and no matter how much boost I ran, I never made more than ~270whp on a stock CT. Personally I believe that on a T4 based setup one could break the 400whp threshold on 440's so long as the fuel pump & supporting mods could keep up. Excessive backpressure from the stock CT turbine housing really reduces its overall efficiency above ~350whp or so.

    On a 62-1 CT26 (not recommended!) and VPC/SAFC/550's I ran as much as 25psi peak boost (falling to 20 by redline) and never hit boost cut thanks to the AFM signal reduction required to map it for 550's w/the VPC.
    On that setup I made 399whp and 428wtq at 19psi on pump gas but it was 10.5:1 or so in boost to try to mitigate knock count.
    With 101 octane I just maxed out my boost controller and that was definitely +50wtq and probably a bit more HP but the stock CT turbine housing was choking things off up top in a big way. With a larger turbine housing and better exhaust manifold, even an ancient 62-1 with a .81 T4 housing would likely have gotten me near 500whp on 101 octane.
    Beyond that, keeping IAT's down with a good FMIC setup is the next step.
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    Quote Originally Posted by Enraged View Post
    .... Doesn't the Maft pro have a built in fuel cut eliminator?
    yes, it has a setting "max frequency output hz" which you can set to 1500,1550 etc


    But after seeing the stock ecm activate fuel cut at 1300 ish hz (3500 rpm and below) I am not using the setting.

    I hope to have it tuned so that Im running a few psi below cut anyway, and can leave it on as a safety. like if my boost controller mac valve blows apart and it over boosts etc

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    That is incorrect. It is fuel cut. I have personally examined the ECU code and can verify this.

    If it was spark cut the catalytic converters would be killed the first time you hit it. It is based on computed load by the ECU. The max limit is when the computed load hits about 80% of full scale. Load is computed from air flow, air temperature and barometric pressure.

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    Super Moderator Wreckless's Avatar
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    Quote Originally Posted by 3p141592654 View Post
    That is incorrect. It is fuel cut. I have personally examined the ECU code and can verify this.
    Fascinating. Interesting to have been wrong about such a small detail for so many years. Any other interesting truths found in the TCCS?

    If it was spark cut the catalytic converters would be killed the first time you hit it.
    I must disagree. Other vehicles run failsafes on spark cut and not fuel cut and this has not been an issue. Nor has been running profoundly rich been an issue for catalytic converters for relatively short periods of time, such as hitting a failsafe momentarily. Running very rich for long periods of time under high loads will kill cats, but it is not an instantaneous or even short-term death sentence, it's a long term one.

    It is based on computed load by the ECU. The max limit is when the computed load hits about 80% of full scale. Load is computed from air flow, air temperature and barometric pressure.
    You wouldn't happen to have a compiled grid of those data, would you? That'd make things easier for the piggyback folks in a big way!

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    ahh its 2018 and the fuel / spark cut debate lives on!!

    A little more information on my setup. my stock 7mgte ECU is always receiving constant values for:
    1) Intake temp and
    2) HAC (altitude) sensor

    the cars stock ecu always thinks its seeing 68 degree intake air. here is some info on that

    http://www.fadingworld.com/CRE/Autom...d%20Codes.html

    Maft-pro handles the temperature (and altitude) compensation --factors it into the AFM signal it sends to the toyota ecu

    so my stock toyota ECU should have very consistent behavior around fuel cut. As 3p said, fuel cut is not a golden "don't pass 1500hz" rule. maybe after 4500-5000 rpm the system allows up to 1500hz on the air flow signal. but not below 4k RPM

    for you data junkies, here is a couple of data logs of fuel cut happening well below 1500hz airflow signal

    3300rpmcut.jpg



    4100rpmcut.jpg



    and to show the system can run without cut, the same (and higher) airflow signal HZ, just with more RPM

    no_cut_5682rpm_1415hz.jpg

    Last edited by madisonMK3; 09-13-2018 at 08:48 AM.

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    90T 3p141592654's Avatar
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    I've posted quite a bit of information over the years on the 7M ECUs. http://www.supramania.com/forum/thre...nalysis.73379/

    I've never seen a production ECU that didn't cut fuel. Filling the engine and exhaust with unburnt fuel doesn't pass the corporate lawyers. But I haven't seen everything.
    Last edited by 3p141592654; 09-13-2018 at 10:53 AM.

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    Quote Originally Posted by 3p141592654 View Post
    I've posted quite a bit of information over the years on the 7M ECUs. http://www.supramania.com/forum/thre...nalysis.73379/

    I've never seen a production ECU that didn't cut fuel. Filling the engine and exhaust with unburnt fuel doesn't pass the corporate lawyers. But I haven't seen everything.
    Oh I have been following that thread on sm and appreciate the work you have put into it and shared with the community. I use to run a fuel only megasquirt (with the original 7mge ecu handling ignition) and that thread of yours convinced me the a stock turbo ecu + piggy back is a better setup (in many ways, for my HP goals etc) compared to original gangster megasquirt 1.... that thread also made me understand the GE and GTE ecu / wiring are very very similar as well. Im the guy that runs the GTE ecu on a 86.5 yellow plug (modified) GE harness + ge igniter and distributor.

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    When was the last time the injectors were cleaned and flow tested?

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    Quote Originally Posted by 220 View Post
    When was the last time the injectors were cleaned and flow tested?
    When I rebuilt the motor, 10 years ~ 10k miles ago I had gb clean/ test them.

    Also dropped tank and did a fuel pump / filter back then. This summer I went back and did the walbro / relay+rewire / Afpr
    Last edited by madisonMK3; 09-14-2018 at 04:07 PM.

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    In all my testing with the Emanage blue the highest HZ 've seen without FC was 1625. As you said there is no magical number but as the RPM's raise the amount of HZ from the AFM can rise as well. Maybe 3p can dump that data to make it easily available for piggyback users to set the limits. This is very much the same on the JDM map sensor aristo engines.

    Depending on the load on my aristo if I had the PSI clamp at 14.5 PSI it would still hit boot cut at lower RPM's if it was too cold and could make too much boost.

    I recommend upgrading to the Walbro 450, if you don't like the noise. The 450 is so much more quite, but on that note, cheating with more pressure is rough because even the 255 doesn't like pressure as the flow goes wayyy down as pressure goes up. I hit that snag on 550's @ around 527 WHP and 50 base pressure with 26 PSI of boost. @ 76 PSI rail pressure, it got much more lean on the A/F as I tried to add a few more PSI of pressure.
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    took the car out to the drag strip today to get some real numbers. ran a best 13.60 @105 (personal best for car as well).... but ran into some issues with heat.

    it was 87 and sunny, my intake air temp pre-run was 110 degrees. my sensor is after intercooler, outside of engine compartment so it does not heat soak. much much hotter than I hoped and also hotter than I had ever tested at.

    my boost would not go much past 11 psi in the heat. car was hittting 14-15 psi in 70's outside temp, hitting max IAT of 90 or so in testing earlier this week.

    today I hit 131 degree intake air temp !! glad I had about 100 octane (50/50 mix of 110/93) in her. she was also lean and mean, 11.5 a/f.


    but I was hesitant to do anything to up the boost since it was so hot. after these runs I am curious to see what I can do hitting 15 psi with 2 digit IAT's.... maybe it has low 13's in it. guy next to me trapped 2mph higher in a mustang and ran 13.04.


    byron2018.jpg



    byron2018log.jpg
    Last edited by madisonMK3; 09-15-2018 at 04:10 PM.

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    have you considered water/meth injection?

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    105mph is the highest trap speed I've ever heard of from a 100% stock CT26 in a full weight MK3.

    You're just totally out of turbo - that's why it's not making any more boost in hot weather. If you had some way of seeing your CHRA rpm I'm certain you're deep into the 'this bitch is going to come apart' territory. Ask me how I know.. lol

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    Quote Originally Posted by Wreckless View Post
    105mph is the highest trap speed I've ever heard of from a 100% stock CT26 in a full weight MK3.

    You're just totally out of turbo - that's why it's not making any more boost in hot weather. If you had some way of seeing your CHRA rpm I'm certain you're deep into the 'this bitch is going to come apart' territory. Ask me how I know.. lol
    106.2 was my best trap. I wish I had her on the scale with me in it, car is an 86.5 Targa/tems/4.3 lsd car, somewhere I thought the 86.5 were lighter. 245/50 on the back, I think Im just over 6k rpm in 4th (cant use 5th under boost, w58 trans...)

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    added more turbo to the equation this year.

    ct26 rebuilt with 57 trim mamba wheel 11 blade with matching mamba compressor cover.

    have only done minimal tuning with the new turbo, but here we are hitting 15psi on stock 440's. somehow not hitting fuel cut.

    base fuel pressure (engine off) is 50 psi. at idle we are at 42.

    I feel like Im close to needing more injector now...or maybe I will turn the fuel pressure up

    apparently fuel cut is based off rpm as well as I can hit very high frequency out HZ (1700) at 6000+ rpm.
    car is not cutting and is running stronger than ever with the larger turbo !! loving it

    Last edited by madisonMK3; 04-13-2019 at 04:22 PM.

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