I started my car after work last week, and it kind of shuddered and sputtered like it wanted to immediately stall. Then it started idling normally, and a couple seconds later the CEL came on. It would then idle fine, but as soon as I touched the throttle it wanted to stall. I tried the throttle a few more times, hoping it would fix itself, but it didn't. So I shut it off and started contemplating the walk home at night in 50 degree weather. Started it again just to make sure I wasn't imagining it all, and it fired up and ran fine. The CEL stayed on for a few days, then went off. It's been running fine for the last few days now.

Will the code still be in there even though the CEL isn't on anymore? Anyone ever experience anything like this? I can only think that it must have been somehow UTEC-related, because I don't have anything else to blame. Some kind of boot-up glitch or something?

 

Bump

 

maybe u tuned the idle too lean

 

Do you have a bypass valve on your car by aem?????

 

I didn't change fueling at idle, the fuel map has ECU in the whole 0% row. And also this only happened once, like something went wrong during UTEC startup or something. I do have the TPS mapping threshold at 1% though, which also made me think it was UTEC-related, since as soon as you touch the throttle the UTEC takes over. All of my low-load and low-RPM mapping values were ECU though, except boost since I'm using closed-loop boost control.

The only mods on my car are exhaust, UTEC (with MAP sensor), boost guage/turbo timer.

 

Nope the code should be gone. Normally there is what is called a freeze frame when you get a CEL. It logs the Cel and everything the car is doing at the time. But when I hooked my car in the CEL had turned off and there was no code stored. So I don't think it will be stored.

When it stalled did you turn the car off and let everything reset or just start it back up. TurboXS recommends you turn everything off so the ECU and UTEC will start up properly. It sounds to me like this is what happened.

Ben

 

The code will still be there.. Its probably a MAF/Map sensor reading low error.. It can be cleared but it will still be there even though the light went off..

This is actually something that used to happen to me on occasion if I just turned on the key and cranked the engine.. The UTEC has a "bootup time" just like most other systems, if you try to crank the engine before its "ready" it will start up, then die.. usually if you crank it again it starts right up..

Remember the UTEC intercepts and regenerates most of the engine's signals, so if its not quite ready, it'll either crank a little longer, or start and not run..

 

Oooh.. I just reread your error.. I have had that specific thing happen.. Its probably a "bank0 O2 sensor rich error" on the ECU.. I found on rare occasions (Since I installed my upgraded intercooler, pipes, and MAF pipe) the car will start and run really rich (I have to presume that the airflow reading in the MAF was high for some reason and caused excess fuel to run through the engine) This would cause it to sputter, idle poorly, and likely trigger the CEL for the O2 sensor detecting it running rich.. Was your A/C On when you started the car?

 

No, it ran funny when I first started it. After I shut it off & started it again, it ran fine.

 

I'm pretty sure the A/C was off because I hardly ever use it. But it's possible it was on.

Why do you suppose the MAF reading would be all messed up like that, and restarting would clear it up? And when you've had this happen, did it idle OK? What was really weird is that the idle seemed normal (after the initial sputtering), it only started to cut out when I touched the throttle. But then it would resume idling normally.

And I always turn the ignition on, then wait for the CEL to flash before I turn it over (when it flashes to show you what map is selected). I don't think I forgot to do that...

 

Yeah, thats the only time I've experienced it happen.. The "Stumble" sputtering or whatnot was probably the signal not being regenerated (the UTEC may not have been fully booted)

Either that or you had a flooding condition for some reason and the plugs were misfiring badly.. If you had your defroster on, the AC compressor cycles and it could have been it also..

Just offering a few suggestions, if you can pull the code from the ECU it will give me more insight.. If you haven't reset the ECU (disconnected the battery) the code should still be there even though the light went off..

The thing that triggers my CEL most often is a Bank1 too rich error.. Then sometimes the light goes off, or if it happens several runs in a row, it stays on.. It didn't start happening until I upgraded my intercooler pipes, intercooler, and MAF pipe..

 

Similar happened to me when I left my 12V to 110V cigarette lighter inverter on which powers the laptop I use to monitor utec.

 

Ya know, thats a good point, I wonder if grounding or load on the electrical system could contribute to it.. I did recently do a grounding kit on my car..

 

I guess I can see how these things could cause a messy start-up, but any idea what was going on after it started? I mean it seemed like the normal high idle, but then it would want to stall when I touched the gas.

Oh, and I do have a grounding kit, but it's been on there for a long time now.

I'll try to see if the code is still in there.

 

I just had a thought.. try switching to a different Map.. see if it still happens..

I inadvertantly made an error in one of my fuel maps once, when I set it to -100 by mistake instead of ECU.. It did the exact same thing your describing and triggered the CEL light.. Until you can tell me the ECU's CEL code, I can't give you much insight, but I do remember that also triggered a CEL.