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Engine trouble help

TTA579

TTA579

South Bay TTA "Barn" Find
Hi guys, long time no see. TTA579 is running but I'm having a little trouble on startup.

After what I still believe is a difficult start, the car will nearly stall about twice while bringing the idle down from 1500rpm or so. After the car settles on ~800rpm and it's warm it appears to have little to no issues. If I try to put the car in gear before the idle has come down it will stall, after that time however, all is well.

Following the idle adjust procedure, the car takes a long time to settle after adjusting the idle screw, almost to the point of not adjusting. I've settled on an IAC of ~45 for now.

O2 count shows leanish (300) at idle, but rich with any sort of throttle (800). Everything else on the scangauge looks normal (using buick numbers). All parts look stock except for the cat-back.

If you have any idea what's going on here, I'd appreciate the help! Thanks.
 
Did you try cleaning the IAC? Take it out and hit it with some carb cleaner to get the carbon off. Also clean inside the IAC port. If that doesn't work, you may need a new IAC, or you could have a vacuum leak somewhere. How about your injectors. They could be clogged, and need to be cleaned. It might be worth getting a Turbotweak chip and some new injectors.
 
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I reread some of your older posts, and I was wondering what you have done to the car so far. I know you had intentions of changing injectors, turbo, etc., plus you had vacuum lines that were disconnected. Have you resolved any of those issues?
 
You're thorough! The IAC and housing are new. I purchased the aluminum angle boss and a new IAC valve and they have been installed.

I've replaced all the vacuum lines and bad check valves with new parts. The vacuum block is also a new billet piece. I've replaced the MAF with a used unit, though I had no indication that the old one was bad either. I've also replaced the MAP. The turbo is running fine, but has not been replaced. The injectors are still original, I have not removed them. The on-rail fuel pressure gauge is showing normal pressure as well.
 
Takes about 20-30 seconds of cranking, or maybe it just feels that long. I'm going to shoot some video of the process this weekend and post it on youtube.
 
A little update: Had a turbobuick forum member come out and take a look with me. Though it wasn't the case until he showed up we saw the IAC drop to zero and couldn't find any other problems. He recommended I pull the IAC plug before it had a chance to nearly stall in the morning.

This morning I did exactly that. No results. In fact, the car still bogged down to ~300rpm twice with the IAC disconnected before normalizing. RPMs gradually dropped to around 1000-800. I drove the car around the block a couple of times. (I need tires!) After parking the car and shutting it down, the car had no problems starting back up again. This is a cold start issue. I know when I start the car tomorrow I can expect similar results.
 
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