cold idle and inital start up issue

hello i recently swapped in a 2004 gto engine into my 1991 240sx. for some reason i cannot get it to idle when its cold and it wont start up and hold idle without me giving it gas fora few seconds. when it finally idles on its on it smells rich.

i tried disconnecting the o2 sensors and no help. i tried disconnecting the iat and no help either. i have new plugs and wires and iacv.

i took the map from the ecu removed vats, unchecked a bunch of codes, and switched the output vss signal.

here is a log of me trying to start it 2 times wihtout giving it gas and then a 3rd attempt with me giving it gas.

Attachment 54751

Attachment 54752

Also I forgot to add, it's a completely stock motor except for intake, headers, and exhaust

Is your fuel pressure the same as the 04 GTO?

I have a corvette fuel filter/pressure regulator. I never actually checked to see if it's putting out 58psi. I'm going to check that first thing tomorrow

i see several issues with the tune from first glance. you are missing lots of numbers on several tables. my thoughts would be to download a stock gto tune and copy over the missing info. that should get you started on initial startup. then you need to run a desired airflow config and copy over the error percent until it gets close to zero.

The thing is that This was a complete swap out of a gto that I saw running fine.I hooked up hptuner and downloaded the map from the ecu and only removed vats, codes, and changed vss signal.

Do u think something happened when I downloaded the map from the ecu?

i doubt it, but i have seen weird things happen. I looked up a stock GTO tune i had and yours is very different. can you try downloading the Russ K Idle Config and do a log with it? i think i might be able to help at least a little. I am currently doing Idle tuning on my Escalade and have run into some initial idle issues also.

btw...the intake swap shouldn't make a ton of difference to the pcm. I have a Super Victor and LS2 92mm TB on my escalade and it would idle straight out of the gate with the stock 02 Express tune i loaded. I also have a centrifugal on it.

i found another stock 2004 gto map on the repository and its the same as mine with the blanks on the idle section.

once I get home, ill try to post a pic of what I saw on my computer. it could be an issue with your, or my software/hardware.

I just found 2 problems.

My ebay corvette fuel pressure regulator is putting 68psi at the fuel rail. I just bought amother one but this time from gm, I'll put that in this week when it comes in.

My other problem is that my orange wires (hot at all times) I wired to ignition 12v. The diagram I used was wrong. I just redid those wires and did the idle relearn and it's idling now but the car was already semi warm so I will try to start it again tomorrow morning

Odom yes please post a pic so I can correct any more issues I have.

so i put a ac delco c5 fpr in and the fuel pressure is now at 62. the idle is better but not 100%. when i start it up the rpms jumps to about 1500 momentarily, then dips to about 4-500 rpms as if it was about to shut off and then raises up to 800rpm

I haven't had time to load my laptop up, but I haven't forgot about you. I'll try to look at it tomorrow. Work let me have a day off. Lol

1 and half year later im still having this issue. i chose to deal with it and hold the throttle till it warmed up but now i really just want to correct it. any help would be greatly appreciated

Normally, it is the idle >> airflow >> friction airflow initial and startup airflow initial that most affect how it starts and holds rpm for the first few seconds, they have delay values also so they drop off after maybe 5s or even less, it varies by car/ecu..(and state of tune obviously).

I assume you ran some idle config checks at some point so that your idle values (in base running airflow >> idle airflow) are near right at the temps you are looking at? The low end values in that table (under 44C) look quite low to me, but I don't know what an 04 GTO should look like!

Another minor point is that the off idle scalar (under Startup, same page) is set to 0, that means that if you touch the throttle during startup, all the initial airflows etc., I just mentioned, are turned off. If you set to e.g. 0.5, they are 'chopped' by 50% instead. It might be good to set to .5 or 1, just to see how the startup airflow items are behaving..

Having a similar problem where i need to press the accelerator to have the engine start. I then hold it for about 5-6 seconds and then slowly release the pedal. After the motor is warm it will run normal but if it shuts off i need to hold the pedal to keep it running.

So under the frictional airflow do you increase the value or decrease it?