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Discussion Starter · #1 ·
I have a 95 Lexus with a strange problem, I just got done swapping in a new motor and started it today and it started great and ran fine. When it warmed up it shut off and wouldn't start. After letting it sit for an hour or so and it cooling off it started back up until it warmed up. The car refuses to fire the spark plugs when its warm and I am baffled. I have the 1100 unit in my car and here is a brief list of the mods, I am including everything just in case it might help.

1JZ bottom end with 2JZ-GE head
Single PT67
Twin power IGN
Uego
6sp
It uses the 1100 EMS w/ 5 bar map and UEGO.

those are the major thing that I thought might matter.

With my old 2JZ-GE boosted setup (only thing different was the bottom end) it ran fine. It did this to me one time @ the track and after sitting it finally started back up. I am just at a loss and have no idea what to check.

I went back over and started the car again after sitting for about 2 hours. It started right up and ran good, I was adjusting on the idle and let it die and it refuses to restart, no spark again. Is there a theft setting where it can't be restarted or anything?

Well I unhooked the coolant temp senor and the reading dropped to zero and the car ran like crap and then died.

PLEASE HELP ANYBODY, I am getting no help on AEM's website.
 

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Bills95TSC300 said:
I have a 95 Lexus with a strange problem, I just got done swapping in a new motor and started it today and it started great and ran fine. When it warmed up it shut off and wouldn't start. After letting it sit for an hour or so and it cooling off it started back up until it warmed up. The car refuses to fire the spark plugs when its warm and I am baffled. I have the 1100 unit in my car and here is a brief list of the mods, I am including everything just in case it might help.

1JZ bottom end with 2JZ-GE head
Single PT67
Twin power IGN
Uego
6sp
It uses the 1100 EMS w/ 5 bar map and UEGO.

those are the major thing that I thought might matter.

With my old 2JZ-GE boosted setup (only thing different was the bottom end) it ran fine. It did this to me one time @ the track and after sitting it finally started back up. I am just at a loss and have no idea what to check.

I went back over and started the car again after sitting for about 2 hours. It started right up and ran good, I was adjusting on the idle and let it die and it refuses to restart, no spark again. Is there a theft setting where it can't be restarted or anything?

Well I unhooked the coolant temp senor and the reading dropped to zero and the car ran like crap and then died.

PLEASE HELP ANYBODY, I am getting no help on AEM's website.


Look at a parameter called "stat synced" and see if it turns on when you are cranking it..... when its warm and will not start.
 

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Discussion Starter · #3 ·
It takes a second to turn on when its warm but it does turn on after a few seconds but never sparks the plugs.
 

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If it's getting "sync" when cranking, but not sparking, check the ignition outputs on the AEM. You can first watch the signal on the laptop (what the AEM *thinks* it's doing). If it says it's sending out an ignition signal, check the actual signal.

I'm not all that familiar with the 1JZ, but does it use an ignitor like the 2JZ-GTE? Or did you remove the ignitor when you went with the twin power? If not, could be the ignition amplifier is not working correctly so the Twin power isn't getting a signal to spark.
 

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Discussion Starter · #5 ·
All I am using is the 1JZ bottom end, I swapped all my sensors and related parts from the 2J, essentially its a 2J with shorter stroke and 2.5ltrs. I will check that when I get back to the shop and let you know what I found. BTW thanks for the help I have been getting nothing from the AEM forum, its easy to get one track minded and other ideas help.
 

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Sure thing. Sorry to hear about the AEM forums. Seems like they're hit/miss on the troubleshooting side. Let us know what you find out about the ignition signal.
 

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Discussion Starter · #7 ·
Okay I drove it a bit today and its driving fine except for running a little rich. I did a test just to see and as I was pulling up to the house I shut it off while still rolling and then put it in second and popped the clutch and it started right up. I then parked it, turned it off and then tried to start it and it wouldn't start again. man this is perplexing.
 
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Yeah, compression start will always override warm start problem. this has to do with your AEM settings, is your IAT reading the correct temp? justin nenni fixed my warm start problem in like 5 seconds, but i didnt get a chance to see what he changed. also, do not drive around like this, if you stall (and it will stall) you will not be able to quickly start back up, and that is just asking for po-po to pull up behind you and ask wtf is going on
 

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Discussion Starter · #9 ·
hmmm, so it might be the IAT. I live in the country and cops are about as common as blue chickens :).

I am going to look at my IAT's real fast though and see!
 

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Discussion Starter · #10 ·
I went back out and now I see that STAT SYNC'D is not turning on as it was when the car was running and when it will start (when its cold). Also the Coolant Temp is under 200 but is shaded red which I take to be bad?

I also checked the IAT and it is working fine and reading correct.
 

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Alpine Hardtopper
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With no "STAT SYNC" the AEM is not going to tell it to spark at all. If you're not getting the SYNC, that's where you want to start troubleshooting. Maybe try recording traces for the crank and cam sensor and see which of the two aren't coming up correctly.

IIRC, the reluctor ring on the crank is a common problem on many cars. And it usually shows up worse as it gets warm. Although it seems odd for both bottom ends to have that problem, so it may be more likely a cam sensor problem. Does the 2JZ-GE use a distributor? You will want to look at the signal coming off of that to see if that's where your problem is.
 

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Discussion Starter · #12 ·
I don't think the GE motor has the crank or cam angle sensors. It does have the distributor instead, I am wondering if it has to do with the distributor being off but then again I wonder why it would only be the problem on a warm restart. I am going to zero out my timing next and see if that helps. I just keep thinking it has something to do with that coolant temperature sensor since it turns red around the time it won't start. I am going to see if I have a spare one on another motor and just plug it in and let it hang free and see what happens.
 

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In the cases where there's no crank pickup the AEM usually wants to determine TDC on #1 based on the distributor signal. Often there's a missing tooth, or second signal for that reference. Record the distributor signal with the AEM and see if it's doing something funny.

I suppose it could be a problem with the coolant sensor. Usually it's not programmed to kill spark when the temp gets too hot though. Most often it just richens up the mixture more.

Just to confirm...the last time you tried to start it when it was warm you were not able to get it to say "Stat Sync"? Are you using the same distributor from your original 2JZ? The AEM needs to see "Sync" before it will try to start at all. Now we just have to figure out why it's not sync'ing.
 

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Discussion Starter · #14 ·
Nope it wouldn't turn the stat sync on not matter what I did. Yes I am using the same dist (with new cap and rotor and wires). I did have it out because the head has been completly redone but I made sure I aligned everything and it started up and runs fine until warm. I am going to check the timing tomorrow, thats what I am down too I guess.

Thanks again for the help and suggestions, it helps me look into different things that I hadn't thought about.
 

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So you are sure you are not seeing stat synced?

If not, this IS your problem and I have seen it before. Because the cam and crank pickups are inductive pick ups, their output can vary according to temperature, rotational speed of the motor, etc. The voltage may be getting too low for the AEM to pick up any signal. The fix to this is to change the resistors for the cam and crank in the AEM unit. These are used as sort of filters, but they will bring down the signal a bit. I have had to lower the resistence of these on some cars that have low cam and crank sensor outputs.
 

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Agreed! If you don't get sync, the AEM won't fire the injectors or ignition at all.

I've never done an EMS in the N/A Supra/lexus, but I did convert one of the 1040 boxes to use in a research van of ours (5.8L Ford). The only pickup on that was in the distributor and it was just an offset tooth. I'm guessing that's what's in your car as well. Since the car starts when it's cold, the EMS is probably set up fine. But it's not getting the signal from the distributor when it's hot. This could be the distributors fault, or the wiring between the distributor and the EMS.

Assuming the only pickup is in the distributor, the alignment of the distributor would not matter at all for getting sync. If ti was off, it would still get sync, but would probably not run, or would run poorly.

Do some more detective work on the sync problem. You won't be able to get anywhere until that one is solved.
 

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Discussion Starter · #17 ·
I am using the 1100 unit from the TT but it was never a problem before. I have an extra distributor so I am going to swap that out and see what happens. Does it look for for different sensors or pickups when warm as opposed to cold starts. I am used to working with HP tuners and LT1 Edit from the domestic side and learning this AEM is taking me a bit. Is it once it goes into closed loop after warming up that it starts looking for these sensors that aren't a problem when in open loop. I know that when in open loop on the other cars I have done it pretty much doesn't care what the other sensors are doing until it warms up.

Would a faulty Knock sensor cause this once warmed up?
 

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The "sync" is not like any of the parameters dealing with open/closed loop, and is not temperature dependent at all. The AEM needs to know where TDC for cylinder #1 is before it sends out any signals for ignition or fuel. For that matter, any ECU that does sequential injection or undistributed spark needs to know that reference before it starts. It really doesn't matter what any other sensor is doing (coolant, air, pressure, knock, tps....anything) if the ECU does not get sync'd.

Look at the distributor signal on the laptop, or record it with the AEM. I'm about 99% sure the problem lies there. You can try swapping distributors as well. But the "sync" parameter is where you want to spend your time.

Also, check out the AEM forums for SYNC posts. They may have some good tips there.
 

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Discussion Starter · #19 ·
Well I decided to just give it to my Buddy (Polk Performace) and let him fix it. I am in the process of relocating to Texas and will be having to sell my shop. It was just easier this way as I was going to have to sell my lift anyway out of the shop. I traded him the lift for building my 383 for the TA and buttoning everything up and Dyno tuning the Lex.

You guys have been a great help and thanks a million!
 
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