I have this reocurring problem, and Ive yet to find somebody who can help me. My car runs fine when I start it up, besides the fact that it won't Rev past 2K rpm. When the car is at operating temperature, it goes lean and studders really bad and then will go back to the rich side. It will cycle like that until the car dies. Car throws the p0100 code and the Maf is good and the wiring is good. So I'm confused. My question is, what else causes the p0100 code? Someone please help me get to the bottom of this I've been battling this for 3 months. The car also won't build boost at all, it won't go past 10in of vacuum without having a problem, and if I step on the gas it dies. Seriously?

What have you done? Boost leak check?compression? Checked mechanical timing? Are you running a 1g cas? Check fuel pressure? Tell us what you have already done.

pauleyman said:

What have you done? Boost leak check?compression? Checked mechanical timing? Are you running a 1g cas? Check fuel pressure? Tell us what you have already done.

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You always come to my aid thank you. I feel your in the struggle with me haha. I've done a BLT, just have a small one at the biss screw. I haven't done a compression test but I doubt that's the problem honestly. Running green 1 CAS at 5 degrees advance timing. 6 bolt block, 2g head. I've backprobed the maf at cold idle and everything checks out. I've traced the wiring to the ecu and that checked out. Things I've noticed; There's a clicking noise from ecu periodically when I drive the car (before it leans out at operating temp) at idle, It runs on the rich side until warm, then sputters lean for 5-6 seconds, then corrects itself. If I push the gas at this point it dies. While cold, the car will NOT build boost at all. 18in of vacuum at idle, and it will make it to 10in before it starts going lean again, even while still cold. I get maf circuit code, evap(no emissions), rear 02 (no cat), and waste gate solenoid codes ( Waste gate solenoid gone) I have an exhaust leak at the flex pipe (speed bump) but the only thing causing the problem is the maf circuit code.

I'm having the same issue. Please post updates as you go. I'm in the middle of fixing my boost leak and I will be able to see if it made a difference and then I will update

Didn't u say there was corrosion found in the ecu? Have u addressed that?

boostdawd said:

Didn't u say there was corrosion found in the ecu? Have u addressed that?

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I thought there was but no, I cleaned off the board and it looks brand new. On top of that I used this ecu right before I changed my turbo and it was just fine, so that leads me to believe it's something else. I was hoping you would be able to stop by and take a good look with me soon so you can get a good opinion

Here's the Ecu

Nice clear picture. Super afc and 1g cas....thats one problem. Clicking is another. Stop guessimg and send that ecu out. 18 inches isnt right. Is this at 750 rpm? If so check your mechanical timing.

pauleyman said:

Nice clear picture. Super afc and 1g cas....thats one problem. Clicking is another. Stop guessimg and send that ecu out. 18 inches isnt right. Is this at 750 rpm? If so check your mechanical timing.

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What's wrong with 1g cas and safc2? When I get enough money I'll send it out to be checked out, unless anyone wants to be my savior and has another ecu laying around? The 18 in is actually at 850 rpm. I raised the idle a little bit. I also noticed on my safc2 the throttle position bounces between 1.8-3.6% at idle. Someone suggested making sure my tps was between .48-51 volts and make sure my plate was closed at idle so I can enter closed loop when the car was warm? Relevant or?

Yes its relevant. Throttle doesnt sound closed. 2g doesnt run well with a 1g cas on its own. Will throw a misfire code. Link can deal with it but safc can't

pauleyman said:

Yes its relevant. Throttle doesnt sound closed. 2g doesnt run well with a 1g cas on its own. Will throw a misfire code. Link can deal with it but safc can't

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Okay so I'll go check to make sure my tps and throttle is in spec. As for the cas, I'm not throwing a misfire code, as I have my spark plug wires reversed in the order of 3-2-1-4 to compensate for that. If I have it on the default setup of 4-1-2-3 the engine won't start and misfires. Anybody got a spare ecu lying around? I'll give the clothes off my back to get this car running haha

DsmDanielson said:

Okay so I'll go check to make sure my tps and throttle is in spec. As for the cas, I'm not throwing a misfire code, as I have my spark plug wires reversed in the order of 3-2-1-4 to compensate for that. If I have it on the default setup of 4-1-2-3 the engine won't start and misfires. Anybody got a spare ecu lying around? I'll give the clothes off my back to get this car running haha

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That isnt how that works. Changing wire order does not fix the problem with a 2g and 1g cas. Just reread your profile.thought you were running a 1g cas. You should not have had to swap plugwires on a 2gb ecu. Kinda confused there.

pauleyman said:

That isnt how that works. Changing wire order does not fix the problem with a 2g and 1g cas. Just reread your profile.thought you were running a 1g cas. You should not have had to swap plugwires on a 2gb ecu. Kinda confused there.

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Sorry let me enlighten you. The PO had a 95 Eprom ecu in the car when i bought it and instead of using the invert cas signal box in link, he just swapped his injector pins. So with the 95 eprom he can still have it on the default plug wire configuration. When I saw the Eprom ecu had a blown sensor ground, I swapped in a 98 Blackbox and swapped plug wires because I didn't want to mess with the pins. Make sense? Now I have the green 1g cas and I don't know why I don't get a misfire code but it works and was working before my turbo blew, so maybe there's something I don't know about that one

Unplug the mas and see if it will rev up. How did you verify both mas and wiring are good? What are you using to see that is goes lean then rich etc.

I fixed my boost leak, no difference. It idles ok, sometimes it will idle up around 2000-2200rpm but if I unplug the maf it will idle fine roughly 1100rpm (280 cams). But if the maf is plugged in or unplugged, it sputters when you try to give it gas. Bad maf?
97 gsx with 6 bolt bottom/7 bolt head 1g black top cas. What was that about swapping plug wires?

Have you or can you datalog anything?

I had the exact issues you are having a few years ago. If I placed my hand over the maf sensor and block airflow it will run/idle better. Turned out to be a bad ecu. I'm confident that is your problem.

I unplugged the mas and there was no change. I'm leaning toward an ecu malfunction and i have kind young man sending one to me to test it. I can log using an obd2 bluetooth connector to my tablet so im going to make sure my tps is in spec, triple check my mas wiring, and throw in that new ecu when it gets here and post results. Boostdawd im beginning to think your right haha i hope you are. Pete, sounds like a bad mas, are you throwing a p0100 code?

To verify that the mas and wiring were good, i backprobed the mas and followed luv2rally's guide for mas testing. Then i traced all the wires from the mas to the ecu and none were frayed or damaged. Thing is my car idles fine. Its when it gets to temp is when it will lean out and struggle to stay running for about 5 seconds then it will correct itself. It will cycle like this until the car dies. Im using a narrowband 02 and an A/f meter and i know i should get a wideband but im able to log front 02 readings and fuel trims so its not like im blind. The narrowband can still measure mixtures at idle pretty well so i know what im seeing is accurate

Link + AEM wideband would go a long way.

Did you already log it and look at fiel trims? Coolant temp? Mas airflow? Anything? Logger should quickly show you what is likely happening.

pauleyman said:

Did you already log it and look at fiel trims? Coolant temp? Mas airflow? Anything? Logger should quickly show you what is likely happening.

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I was able to see the coolant temp getting the proper reading, but the mas reading was not working on the logger but it was showing 35-45 at idle on the safc2 which is within normal spec. I couldn't keep the car on long enough to see fuel trims. Boost, I know link and a wide band goes a long way, but not everyone has that kind of money. You have to make do with what you have.

Not enough info to go on just yet but still sounds like ecu.

Yeah I logged it today. Coolant temp was at 178° F and intake air temp was 132°F when it started the sputtering thing. The p0100 code was because I was putting the car on hotwire to start it and it wasn't reading the mas. After clearing the code it didn't come up again once I left it on karman. To get it started on karman I had to screw the biss all the way in. It idled at 20 in of vacuum at 600 rpm and wouldn't idle any higher. Feathering the throttle got me to 2K rpm but no higher. O2 voltage would fluctuate at .10-.15 volts and when the car was fully warm it dropped to 0. My tps was at like 1 volt so I adjusted it until it was at .50, this is ultimately what let my car start idling on karman while engine was still cold, so that's a fix. My fixed SAS is adjusted properly. I backed it out until the pin lightly touched the throttle hammer, then gave it 1 1/2 a turn and tightened up the locknut so that's in spec now. Idled pretty poorly around 500-600 rpm until it warmed up then then the sputtering came back. If I pressed the gas hard at all it died still. Ecu clicked one time then I never heard a sound from it again. Once car died at operating temp it wouldn't come back on. It would start right up and immediately die due to lean condition. But while the car was cold, it idled at a slightly rich condition and I was able to feather throttle so I know it wasn't the fuel pump.

You know what?!?! I think it is the ECU. When the car was running still, I was driving to oreilly's and my ignition shorted out and melted all the wires underneath my steering wheel. It blew my ignition fuse and everything. It was all due to the fact I have a push button to the battery, and the PO never put a 30 amp fuse like he was supposed to! I fixed that though, but i was reading a forum that said overvoltage on an ecu is defiantly a killer, and the way you could tell was a slight bubble on the flat metal surfaces of the ecu, which I noticed a few on mine. If that's the case, the ecu that is being sent to me to test should do the trick!