88GT 3.4 DOHC turbo 5spd
2 Main issues,
1 it will not idle, sometimes it will, more often than not when its dead cold and pretty regularly right after I run the crap out of it. Every now and then it will just idle perfect out of the blue, then eventualy go back to its normal behavior
It will idle fine at high idle, 1600, but when it drops to low idle~800 it usualy misses the mark and stalls, other times it will drop to 1000 then slowly decrese and level around 800 then stall. I have checked everything I can think of, the car idled flawlessly before the turbo, it has since had 10*retarded intake and 4* advanced exaust cams and 36lb injectors put on, other than that and an alternator, its all the same. But it just dawned on me, I took out the ACdelco plugs and put in NGK plugs that are 2 heat ranges ?higher?maybe lower, whichever it was reccomeneded to do with a turbo, anyway, maybe this is the problem? Its odd that it idles perfect after I run the crap out of it and for up to 10 minutes until it cools down. What do you think?
2: It does not like to cruse at 1-5% throttle, if im running 55 and just barely touching the throttle and vac guage is <6psi the A/F guage will move so fast rich to lean that it pretty much stays lit all the way across, and the engine will rapidly shift between accell and no power, shaking the car violently. This ONLY occurs in this condition.
Okay been working with darth on this, he has pretty much told me it almost posistively isnt in the programmings for either

So could the plugs be the cause of one or both?? ideas?? Ive checked and replaced the IAC, re routed cleaned and insulated the wires, verified all sensors through a laptop, checked the coils for spark all seems in good shape,

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I know you said you have new wires but I have had new ones out of the box leak to ground causing this same issue.

For some reason I keep thinking O2 sensor - don't know why

O2 is twice new and now heated and its been doing this since day one without exception. The O2 does make sense Mabye a pinhole exaust leak? letting a little air in somehow at low power conditions?

How about a burnt valve? If I plug 3 of the exaust outlets, and hold a piece of paper in front of the 4th I cant tell for sure but it does seem like it might be sucking in a little....

The plus wires Ive wrapped in wire loom and mounted in holders and routed as best I could, I can dump water on them and it doesnt change anything.

honestly, just hearing your description, it sounds like you are loading up with fuel at idle.
pull a plug when it stalls at idle. if it's wet, or black and wet, you know what the cause is. then work it back from there.
Betcha you find it wet and black.

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Tom
88 GT 2.8l 5spd
76 30' ChrisCraft Tournament S/F
who has time for anything else?
Vodka: it's not just for breakfast!!

quote Originally posted by tjm4fun: honestly, just hearing your description, it sounds like you are loading up with fuel at idle. pull a plug when it stalls at idle. if it's wet, or black and wet, you know what the cause is. then work it back from there. Betcha you find it wet and black.

This is excellent --I did a rebuild and went to war with this issue for a year until I discovered the above.
I think tjm4fun made a pretty good call on this one.....

So you think it would be better to go out an drive it, start it cold, or run it hard ? then stop and let it idle until it stalls, then check the plugs?