B-Body.org

brentalan · Posted: Mon Aug 11, 2008 5:20 pm Post subject: help with idle

Hi folks,

I'm having trouble with my '88 Classic. I'm not great with repairing/troubleshooting so plz bear with me, I'm learning (thanks to this and other forums). Anywho, I have a rough/low idle when the car is hot, but only after it's been sitting. For example, lets say I drive it, park, come back 2 hours later (esp. on a hot summer day). It will start right up but then the idle will be real rough. Usually will stall when I put it in gear. Also will stall at stoplights/stop signs. If I start it cold, it runs fine, even after driving for an hour stopping at lights and stop signs. It has to run through a heat cycle cool SOME then run again for this to happen. Any idea what I should check? Thanks in advance........

robotic_junky · Newbie Joined: 04 Feb 2008 Posts: 10 Location: Indiana

Take you Ignition Control Module out and take it to Autozone and get it tested. The ignition control module is inside the dist. cap and has 2 plugs on it with about 4 or 5 wires going to it. A lot of ign. control module like to go bad by running fine when cool, but once it's hot the motor will run bad.

If not that, check your MAP sensor.

brentalan · Posted: Tue Aug 26, 2008 7:35 am Post subject:

Thanks! I wasn't sure where to start with this one. I've tried a bunch of things but neither of those two!

robotic_junky · Newbie Joined: 04 Feb 2008 Posts: 10 Location: Indiana

Ign. Control Module usually goes for around about $10 and a MAP sensor usually goes for around $45. If you are sneeky enough, just buy both and try both, but if the MAP sensor doesn't help just return it and say the other part fixed your car, if they ask any questions.

rabidmadman · Posted: Sun Mar 07, 2010 9:29 pm Post subject:

so what was the problem here? I have a similar issue. My car starts alright, and idles rough. When I shift into D, it stalls out. After it stalls out I start it again and it stops stalling out. My first guess is that it could be the TPS because I noticed some weird throttle issues when hitting the gas....god damn I don't want to take off the carburetor again.
_________________
1988 Chevy Caprice Classic Owner.

Engine: 305 V8

Location: New Jersey

robotic_junky · Newbie Joined: 04 Feb 2008 Posts: 10 Location: Indiana

When I tried answering brentalan's question. I was going on guessing it was TBI (Throttle Body Injection)

With TBI, I've seen if a car runs fine cold, but runs rough or stalls out when hot then it would be the Ign. Control Module.

I've also seen TBI start fine, but when put in gear(a load on the motor) and stalls out then it would be the MAP sensor.

I don't know really know much about carbs. I'm a F.I. person.

brentalan · Posted: Mon Mar 08, 2010 8:47 am Post subject:

My car isn't TBI, it's the same as you Rabid, '88 305. The problem turned out to be the timing was off. The high idle allowed it to run well enough with the advanced timing but it was too far advanced to keep an idle.