I have this beautiful '88 Convertible that I have had tucked away for a few months that I started working on this week and have since I've owned the car it wont stay running at idle. When I move it around I basically have to keep my foot on the gas a bit to make sure it doesnt die. The car is bone stock. No smoke and it accelerates and drives so nice. No sputtering at acceleration, just wont idle! Since the beginning of the week the only thing I've done is replace all the belts as well as the a/c compressor (the clutch on the old one had seized) and that's about it. What are the most common things I should be checking on for this type of car to see if I can snag the culprit behind my issue?

 

vacuum leak?

 

That was my first though too, but I checked and re-checked all my hoses and tubing and couldnt find a single thing out of place. Well, but actually I do have one questionable spot perhaps. I'll take some shots of it tomorrow. Just maybe if might be the problem but anything else to check?

 

try adjusting the tps sensor that usually helps

 

tighten the throttle cable!

 

I had the exact same problem. I checked all my vacuum lines and they were fine. Was quite frustrated. I started removing the emissions since it appeared to have been half done already by the previous owner, and found that the intake manifold wasn't even bolted down. The nuts were finger tight. I thiiiink that would most likely cause a pretty decent leak.
So since you know your vac lines are good; you have to start checking mating surfaces between your afm and the block. So intake elbow fitment, throttle body, UIM, LIM.
I think you can do a trick where you spray a little starter fluid or carb cleaner in a suspected spot and listen for idle improvement, but I'm not sure how well this actually works as I've never tried it.

 

Don't forget the BAC valve

 

+1

This to keep it running until you can find the problem.

 

Ok. What's the proper way to adjust the throttle cable. Which way do you adjust to tighten properly? And I found there was no hose connecting to the back of the air pump. The lower connection point? How much bearing would that have?

 

Here is one tube that wasnt connected. It's very small though. Looks like it comes from the back of the lower intake.



Oh and I tried adjusting the screw on the top of the throttle body and got the car to go from dying right when I cranked it up, to bouncing between 1K and 2K for about three seconds, and then slowly falling back down and dying. I made my own little diagnostic tool too with the LED lights just for giggles and no codes to be thrown.


Also, do I adjust the TPS by the screw that sits right near it?

I'm drowning here.

 

Spray that tube with a shot of carb cleaner and see if the idle changes.

 

alrighty! I shot that little tube with some carb cleaner and the car actually held an idle for about two minutes. First time since I've owned it that it would hold an idle at all. It idled at just under 1K. I honestly dont know what that tube even goes to though? And if in fact for sure that is the culprit? Can a tube so small really be a legitimate factor?

 

Any sort of vacuum leak will wreck havoc on the idle of a car.

 

I did a little work with the TPS. I turned the adjusting screw about 1 1/2 times Clockwise, and now the car will idle between 700-750. It does a little bouncing between the two, but it stays between those numbers. I'm not sure if that was the fix or not, but at least the car will stay running now so that I can try some key areas with the carb cleaner and get more exact results I think.