94 Trans Am Rough Idle - Forced Induction
#1
94 Trans Am Rough Idle - Forced Induction
Can someone take a look at my log file and provide some direction on what I need to do to get it running right. Attached is a log file from SCAN9495 of the car at idle. Also if I try to give it gas it tries to die out, this is not in the log file. I can take another log log of that if needed. Thank you for your help.
Here are my engine mods if it helps. Cam, port matched heads and intake, delteq, vortech s-trim, 60lb injectors, electric water pump, dual intank fuel pumps.
DavidS
Here are my engine mods if it helps. Cam, port matched heads and intake, delteq, vortech s-trim, 60lb injectors, electric water pump, dual intank fuel pumps.
DavidS
#2
Re: 94 Trans Am Rough Idle
I'll take a quick look at it, but I haven't reviewed a lot of forced induction tunes.
Opening the log, it's not really useful. Run time is only 92 seconds, not enough for the PCM to go into closed loop. Typically, takes 206 seconds (programmed time out value) to enter closed loop, and coolant temp has to be above ~120*F. Your coolant temp has only reached 108*. Third requirement is O2 sensors hot enough to work, and flags indicate both left and right sensors are ready. Are you possibly running an open loop tune? If it's not an open loop tune, you have to start it and run it for at least 5 minutes to get anything meaningful. Probably a good idea even with an open loop tune, to get the coolant temp up to "normal".
Idle had a cyclic surge pattern. Programmed idle is 950 to 988 RPM (varies with coolant temp). Your idle is cycling up and down over a range of 850 - 1130 RPM. The IAC is not responding to the surge. Not sure if that is typical for a FI setup. Who tuned it?
Are you running a 1-bar MAP sensor tune?
I've seen people post logs for review in the Forced Induction forum. Not sure is they get any responses. In this case, I think it would be a good idea for me to copy this thread to the FI forum. Normally we don't like a thread posted in multiple forums, but there is not a lot of traffic on Forced Induction any more. But there are a few smart FI guys that will help if they show up.
Opening the log, it's not really useful. Run time is only 92 seconds, not enough for the PCM to go into closed loop. Typically, takes 206 seconds (programmed time out value) to enter closed loop, and coolant temp has to be above ~120*F. Your coolant temp has only reached 108*. Third requirement is O2 sensors hot enough to work, and flags indicate both left and right sensors are ready. Are you possibly running an open loop tune? If it's not an open loop tune, you have to start it and run it for at least 5 minutes to get anything meaningful. Probably a good idea even with an open loop tune, to get the coolant temp up to "normal".
Idle had a cyclic surge pattern. Programmed idle is 950 to 988 RPM (varies with coolant temp). Your idle is cycling up and down over a range of 850 - 1130 RPM. The IAC is not responding to the surge. Not sure if that is typical for a FI setup. Who tuned it?
Are you running a 1-bar MAP sensor tune?
I've seen people post logs for review in the Forced Induction forum. Not sure is they get any responses. In this case, I think it would be a good idea for me to copy this thread to the FI forum. Normally we don't like a thread posted in multiple forums, but there is not a lot of traffic on Forced Induction any more. But there are a few smart FI guys that will help if they show up.
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