skruff

Hello everyone again. Now that I have my car tuned and figured out my boost leak issue, I am tackling the only issue I have left: rough idle during a cold start.

2006
Descendent Turbo kit
AEM FIC 6 with resistor mod
Stock fuel pump
Spark plugs replaced 3 months ago
I have an obd2 reader

When I went to leave the tuner after they were finished, the car bogged down ~5s after I turned the ignition key. I tried it again and the same thing happened. Tuner played with the throttle for the first few minutes until the car warmed up and then every start after that was fine. He told me that without a standalone, there is only so much they could do, and that I will learn to drive the car around the issue.

Since then I have been doing the same thing. I also noticed that this was not neccessary on days where the temperature was above 70 outside. My primary concerns are 1. if I take off without letting the car warm up, it will die within the first minute or so of driving if I don't manually keep my rpms up in neutral. 2. is this going to get ten times worse once winter rolls around.

From what I've gathered, this is an uncommon issue with the AEM FIC (and a good tune) but a common issue with the Emanage. It also appears as though I can modify my fuel map, particularily on the low pressure side, to remedy this. Would I be correct in that assumption?

Any extra help in this would be greatly appreciated. I am not a mechanical guy by any means, but it is a passion that I'm finally able to dip into. I appreciate everyone's patience in helping me out as I learn more about automotive performance upgrades and general repairs/upkeep.

bbsciontc

My only guess would be that the idle range of fuel map (as well as the injector response time in the setup menu) may not be set properly. My guess is that for some reason or other, you are getting too much/too little fuel at idle on a coldstart, when the ECU is in open loop. Once the car is warm, it switched to closed loop and uses your primary oxygen sensor to adjust the fuel and bring it to an ideal range.

I don't know if this is your issue, but this seems plausible. Care to post up screenshots of your fuel map from the fic, as well as injector response time value?

bbsciontc

Also, I see you have an obd2 reader. When the car is warm and idling properly, monitor the STFT and LTFT (short and long term fuel trim, respectively). If they are large positive or negative numbers (say 10 or more), then the ECU is adjusting for an improper fuel quantity at idle.

skruff

Thanks for the info, I'll have time to check it out this weekend and I'll report back.

Side note- I upgraded my fuel pump and spark plugs yesterday. It was reasonably warm this morning, but when I started my car, it didn't immediately die. Perhaps that also had something to do with this issue...

bbsciontc

that is a possibility, although a new fuel pump shouldn't have that dramatic of an effect at idle since the pressure is still controlled by the ecu through the FPR. The slight change you noticed might mean that you are on to something with respect to fuel. Check the fuel situation too, as that might cause the plugs to foul if the fueling is way off at a cold start idle. FYI, I will be away for a week or two, but I will check back on your thread and try to help you out. Not much activity on this forum lately, so the few of us who post need to stick together, lol.

skruff

Awesome. Thanks for the heads up, I appreciate it.