JLee's 1991 Toyota MR2 Turbo build thread

[TheHashmaster]

Thanks! ~2900lb.

that things gonna fly, lol.

 

[jlee]

http://www.youtube.com/watch?v=N3OiDeV2RWk

More complications - flickering check engine light and an intermittent stumble. ECU is showing Code 14 "Ignition Signal. No IGF signal to ECU 4 - 5 times in succession," referring me to the igniter (already replaced), ECU (should be good), or Ignition circuit (+B, IGT, IGF). Pages 62 and 79 in the factory service manual...time to break out the multimeter!

 

[exdeath]

http://www.youtube.com/watch?v=N3OiDeV2RWk

More complications - flickering check engine light and an intermittent stumble. ECU is showing Code 14 "Ignition Signal. No IGF signal to ECU 4 - 5 times in succession," referring me to the igniter (already replaced), ECU (should be good), or Ignition circuit (+B, IGT, IGF). Pages 62 and 79 in the factory service manual...time to break out the multimeter!

Don't think a multimeter is going to help you with high speed signal glitch capture. Really need an o scope for ignition troubleshooting.

At least the problem is simple. It's either ignition module, coil, distributor, or any wiring or connectors between the three and the ECU. :biggrin:

I add coil just because the ignition module simply passes the primary waveform straight through as your tach/ignition confirm signal.

 

[jlee]

Don't think a multimeter is going to help you with high speed signal glitch capture. Really need an o scope for ignition troubleshooting.

At least the problem is simple. It's either ignition module, coil, distributor, or any wiring or connectors between the three and the ECU. :biggrin:

I add coil just because the ignition module simply passes the primary waveform straight through as your tach/ignition confirm signal.

Here's a relevant page from the FSM:

The initial test is easy...the rest might suck.

 

[alkemyst]

why not take it to a pro at this point?

 

[exdeath]

Lol @ "Try another ECU". Because even professional mechanics happen to have a store room stocking spare ECUs for every make and model and engine variant from now to 20 years ago.

Problem is that is a crude test that is picking up DC equivalent RMS from what is really a continuous waveform, and the glitches you are having are going to be intermittent and so fast and scarce it won't show up with a simple DC multimeter. I suspect those tests will pass.

You might have better luck with a needle based analog multimeter. You have a better chance of seeing needle deflections vs a rapid change in a number on a LCD.

 

[sjwaste]

Are you using the original wiring harness? If so, check the igniter ground, the main ground, and then the wire from the igniter to the coil.

Common on the Supra, and it's usually a bad ground.

 

[exdeath]

Do you have a 5 wire cap with an external coil or the 4 wire cap with the internal coil and a small second connector to the distributor?

Every intermittent stumbling and ignition issue I've ever had on my Camry has always been the coil, so that's always the first place I look.

If the primary doesn't fire correctly you won't get IGF; often temperature related as the coil heats up and starts acting funny.

 

[jlee]

Are you using the original wiring harness? If so, check the igniter ground, the main ground, and then the wire from the igniter to the coil.

Common on the Supra, and it's usually a bad ground.

Yes, it's the original wiring harness. Will do, thanks.

Lol @ "Try another ECU". Because even professional mechanics happen to have a store room stocking spare ECUs for every make and model and engine variant from now to 20 years ago.

Problem is that is a crude test that is picking up DC equivalent RMS from what is really a continuous waveform, and the glitches you are having are going to be intermittent and so fast and scarce it won't show up with a simple DC multimeter. I suspect those tests will pass.

You might have better luck with a needle based analog multimeter. You have a better chance of seeing needle deflections vs a rapid change in a number on a LCD.

Heh, I actually do have a spare ECU, but it'll run way too rich since it's a stock one assuming an OEM fuel system. I'll follow the FSM steps and see what happens; if that all checks out OK I'll start looking into alternatives.

 

[jlee]

Do you have a 5 wire cap with an external coil or the 4 wire cap with the internal coil and a small second connector to the distributor?

Every ignition issue I've ever had on my Camry has always been the coil, so that's always the first place I look.

5 wire, external coil. I could just replace it and see what happens, but ATS said my ignition system was fine and MR2OC says Code 14 will not be caused by a bad coil. It also doesn't seem to be affected by time or heat.

 

[exdeath]

5 wire, external coil. I could just replace it and see what happens, but ATS said my ignition system was fine and MR2OC says Code 14 will not be caused by a bad coil. It also doesn't seem to be affected by time or heat.

Hmm I don't know about that. IGF signal is driven directly by the waveform from the primary coil. If the coil were to not fire or not fire correctly for a few cycles, there would be no IGF generated (and stumbling for obvious reasons). The whole point of IGF is to know the coil fired.

Check this out, page 6.

http://www.autoshop101.com/forms/h39.pdf

Reason I suggest coil is that if the ignition module IGF signal was faulty then you'd simply have a "false" DTC but shouldn't have "real" stumbling since it would be a reporting error in that case and not an actual ignition failure. The fact that you have stumbling indicates the IGF failure is telling the truth and you have a real lack of ignition event. Now then to figure out of it's the coil itself or the module, or a harness issue not delivering IGT to the igniter consistently But we already knew that.

 

[jlee]

Hmm I don't know about that. IGF signal is driven directly by the waveform from the primary coil. If the coil were to not fire or not fire correctly for a few cycles, there would be no IGF generated (and stumbling for obvious reasons). The whole point of IGF is to know the coil fired.

Check this out, page 6.

http://www.autoshop101.com/forms/h39.pdf

Reason I suggest coil is that if the ignition module IGF signal was faulty then you'd simply have a "false" DTC but shouldn't have "real" stumbling since it would be a reporting error in that case and not an actual ignition failure. The fact that you have stumbling indicates the IGF failure is telling the truth.

My tachometer will also momentarily cut out and drop towards zero, even if it's impossible for the engine's RPM to drop (i.e. when I am at a steady speed in gear). The tach is likely driven off the IGF signal (hence the drop), and it'll happen even when I'm not on the throttle...hmm, I wish I had a spare coil to test with. They're not nearly as cheap as the (used) igniter was.

 

[exdeath]

My tachometer will also momentarily cut out and drop towards zero, even if it's impossible for the engine's RPM to drop (i.e. when I am at a steady speed in gear). The tach is likely driven off the IGF signal (hence the drop), and it'll happen even when I'm not on the throttle...hmm, I wish I had a spare coil to test with. They're not nearly as cheap as the (used) igniter was.

Could be either. I believe when I scoped the tach signal from the diagnostic port it was just the primary waveform with the tach simply counting trigger pulses from the firing line peak voltage. I think it was just IG- straight from the coil, at least for mine it is. It's just a pass through from the ignition module.

Either way it means the same thing. IGF is just the primary waveform from IG- filtered to produce a square wave that is safe for the ECU and to isolate the ECU from EMF (eg: through a comparator/threshold measuring circuit and a switching transistor output).

Need to know if IGT is getting to the 5 pin connector on the igniter consistently. If it isn't, then problem is before the igniter (ECU and harness). If it is, then problem is with igniter or coil actually failing to fire. Intermittent problems are very hard to diagnose without a scope. Often cheaper and more effective DIY to just take a guess after narrowing it down to 1-2 parts and "rent" them from a parts store that allows returns.

 

[jlee]

I called ATS today - Aaron confirmed that it could be a wiring problem causing the ECU to not get the signal that the engine had spark (he also confirmed that a flickering CEL was normal for a Code 14). The other option was there is an actual ignition issue triggering the code (and not faulty wiring giving a false code). He suggested that the coil could possibly be the culprit - I mentioned plugs and they said that is possible as well. He also offered to test my ECU (all I'd have to do is send it to them).

ATS replaced the plugs not too long ago (probably have 200 miles on the car since the dyno and they were replaced then), but plugs are cheap so I thought I'd try that first. I picked up four new NGK BKR7E plugs and a coil. The coil is annoying (it's under the igniter, which is under more shit) so I just did plugs first...and the problem seems to have disappeared. I haven't driven much yet (just to get fuel), but it feels fine - I'll put some miles on over the weekend and see what happens.

 

[jlee]

The problem came back - 7 times in 9 miles, then 3 times in the return 9mi trip.

I replaced the coil today; it idled mostly-fine (stuttered once prior to ECU reset) and it's not showing any codes since I cleared the ECU, but I'm not holding my breath. The old coil was rusting pretty badly on the bottom- if it was supposed to ground to the bracket, it couldn't have been doing a very good job. I cleaned the bracket before reassembly, so if that was an issue it's not anymore.

All that's left in the ignition system is cap/rotor and plug wires - I'm due for them anyway, so I'll replace them and if I still have a problem, the ECU is going back to ATS Racing for testing.

 

[jlee]

I called ATS Racing and they are sending me a replacement ECU to try- hopefully that will solve the problem.

 

[FuzzyDunlop]

I called ATS Racing and they are sending me a replacement ECU to try- hopefully that will solve the problem.

ECU yet? this things been in limbo.

 

[Black2na]

there waiting for Chips to come in From Japan

 

[jlee]

ECU yet? this things been in limbo.

They're waiting for new ROM boards to come in from Japan.

I can actually run E85 on my current setup if I swap the stock ECU back in (it thinks I have 440cc injectors, so 540's with higher fuel pressure evens out the additional fuel needed for E85), so I may try that and see if that fixes the problem. If so, it's the ECU and I'll either wait for a replacement from ATS or go to a standalone (Apexi PowerFC).

 

[jlee]

No stuttering so far, but it's only been ~22 miles.

 

[PlasmaBomb]

Welding is not that hard, however; you have to know what you are doing. The biggest problems are usually poisoning yourself.

I often find it hard not to poison myself even when I know what I am doing...

oh wait.

 

[PlasmaBomb]

No stuttering so far, but it's only been ~22 miles.

Now you need an E85 tune...

 

[jlee]

Now you need an E85 tune...

With my injector size and fuel pressure, the stock ECU can run the car on E85. The only issue is I will run out of fuel at 275whp, so I have to run low boost. It may have been the ROM tuned ECU that was causing an issue, so I swapped to stock.

A proper E85 tune with 1200cc injectors would be fantastic - 22psi daily driven, ~340rwhp... :awe:

 

[PlasmaBomb]

With my injector size and fuel pressure, the stock ECU can run the car on E85. The only issue is I will run out of fuel at 275whp, so I have to run low boost. It may have been the ROM tuned ECU that was causing an issue, so I swapped to stock.

A proper E85 tune with 1200cc injectors would be fantastic - 22psi daily driven, ~340rwhp... :awe:

Would you really need 1200cc injectors?

I was more talking about taking advantage of the charge cooling nature of ethanol and it's higher octane rating... surely with a good tune it could run >330rwhp with your current set up?

 

[jlee]

Would you really need 1200cc injectors?

I was more talking about taking advantage of the charge cooling nature of ethanol and it's higher octane rating... surely with a good tune it could run >330rwhp with your current set up?

Not enough fuel - 540cc injectors with higher base fuel pressure will run out of fuel around 275whp with E85. Otherwise, yeah-- I am at 328whp on race gas, and I'd run another 1-2psi on E85 so 330-340whp wouldn't be a surprise.

800cc injectors could bring me to ~375whp, which is tempting.