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Discussion Starter #1
Hi all,

I have an 88 that is pretty much bone stock. It seems like it’s running rich (aem air/fuel meter) on idle usually around 17-18 and I know it’s not wrong because I can definitely smell the gas it’s throwing in there.
Also it doesn’t seem to idle smoothly except when I have the a/c on (runs around 17). On startup it will run okay but then it slowly starts to drop in rpm and starts stuttering. I have a video I can upload for you guys to see what I’m talking about.
This also happens when I start her up within a certain time period. IE go to a friends house for 1-2 hours come back and turn her on. She won’t idle like the first start of the day. It’ll be hovering around 500 rpm doing the bouncing/stuttering thing again.

Any advice? I changed the air filter but that didn’t seem to do much. The only other thing I can say is that this seemed to have started happening once I took it to a shop to get the engine gaskets replaced. Suspect a vacuum leak maybe?

Thanks for any and all help!!
 

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Check your vaccum lines, check your intake for cracks. Is this a turbo? I dont think I saw that mentioned.

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17-18 is lean, not rich. It might be stuttering because it's wanting more fuel. Definitely check for a vacuum line that's off or maybe has a hole in it. If you haven't changed your vacuum lines out, it doesn't hurt to swap them all out one at a time with new lines.
 

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Discussion Starter #4
Check your vaccum lines, check your intake for cracks. Is this a turbo? I dont think I saw that mentioned.

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Yes it’s a turbo. I’ll have to inspect everything I guess

17-18 is lean, not rich. It might be stuttering because it's wanting more fuel. Definitely check for a vacuum line that's off or maybe has a hole in it. If you haven't changed your vacuum lines out, it doesn't hurt to swap them all out one at a time with new lines.
Ah okay. Am I correct to assume that anything under 12 would be rich?
Looks like I’ll have to I’m looking for a kit right now. I’ll keep you guys posted thanks so much for the replies guys!!
 

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You want to idle around stoichiometric, 14.7. Under WOT you want to be in the 11s or 12s, but this is dependent on turbo airflow, IAT, and fuel.

You say you are running in the 17s at idle, which is lean (not enough fuel), but that you also smell fuel. To me I would be looking for an exhaust leak that would allow fresh air into the exhaust system before the O2 sensor causing the ecu to think it is lean and then adding too much fuel to compensate.

This could also very easily be a simple vacuum leak.

Which gaskets were replaced?
 

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Discussion Starter #7
So just a small update the timing was off on it (it failed smog) and has too much CO emissions (not burning all the fuel I think). Timing is all good and it idles better but it's still not handling rock solid like it should and its still running crazy lean. I also notice I smell gas at the rear of the car and not in the front like I had first thought. We replaced the AFM on this car and now she doesn't stutter under boost but again, still didn't fix the issue.

There's also a new issue where it will not hold a certain range of you put the throttle down in neutral. 1750-2500 rpm range. You put your foot down to hold it at that range and it will just drop, then go back up, then drop. If you go over it will hold. Any ideas?

You want to idle around stoichiometric, 14.7. Under WOT you want to be in the 11s or 12s, but this is dependent on turbo airflow, IAT, and fuel.

You say you are running in the 17s at idle, which is lean (not enough fuel), but that you also smell fuel. To me I would be looking for an exhaust leak that would allow fresh air into the exhaust system before the O2 sensor causing the ecu to think it is lean and then adding too much fuel to compensate.

This could also very easily be a simple vacuum leak.

Which gaskets were replaced?
This sounds like it could be it.
We replaced the valve cover, cam shaft, and crank shaft seals as well as the o pump.
I hit full boost today and it hit 11s so I think it's fine. When I'm driving around it handles around 14-15s. The mechanic checked for any vaccum leaks and I did as well but I don't hear/see anything for that.

Thanks again guys. I'll keep working on this cause I'm sure I'm not the only one that will have this issue and these forums have helped me out already with other stuff.
 
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