High idle problem solved...
Thread Starter
Instructor
Joined: Sep 2012
Posts: 249
Likes: 2
From: Watkins Glen NY
High idle problem solved...
Since buying my 1991 in September it has idled high. It was high enough that the tranny was trying to go and I was holding the car back at traffic lights. I would just shift into Neutral. Also when I would hit the cruise button to drop a MPH, the car would slow and then speed up even faster. If I tried to set the cruise @ 30 mph it would go right to 36.
I understood that I couldn't adjust the idle because it was in the ECM. I read that there is an idle screw, but it was blocked off @ the factory. I had access to a ODP scanner at work but I really don't know much about it. I have a former background in ladder logic and CNC programming so I thought I could figure it out.
Anyway I had a chance to look at it today. Someone had popped out the plug for the idle screw hole, so I'm guessing this was an issue for the last owner.
When I backed the screw off the throttle plate didn't move with it. This made me think that the return spring was loose/broken or needed adjustment. I grabbed the tools to take all the cables off the plate so I could see how to adjust the spring. When I took off the cruise control linkage I noticed that the plate was up against the idle screw. I backed the screw off more and the plate moved more.
I started the car and it idled right down to 850 or 900 rpm's
I looked at the other end to see if there was adjustment to the cruise cable. There was 6 or 8 different holes for the cable to clip into, so I tried the next hole that would loosen it up.
Took it for a test run and it works perfectly. It idles great at lights and the cruise works like the one in my pickup (same lever).
I understood that I couldn't adjust the idle because it was in the ECM. I read that there is an idle screw, but it was blocked off @ the factory. I had access to a ODP scanner at work but I really don't know much about it. I have a former background in ladder logic and CNC programming so I thought I could figure it out.
Anyway I had a chance to look at it today. Someone had popped out the plug for the idle screw hole, so I'm guessing this was an issue for the last owner.
When I backed the screw off the throttle plate didn't move with it. This made me think that the return spring was loose/broken or needed adjustment. I grabbed the tools to take all the cables off the plate so I could see how to adjust the spring. When I took off the cruise control linkage I noticed that the plate was up against the idle screw. I backed the screw off more and the plate moved more.
I started the car and it idled right down to 850 or 900 rpm's
I looked at the other end to see if there was adjustment to the cruise cable. There was 6 or 8 different holes for the cable to clip into, so I tried the next hole that would loosen it up.
Took it for a test run and it works perfectly. It idles great at lights and the cruise works like the one in my pickup (same lever).
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
I understood that I couldn't adjust the idle because it was in the ECM. I read that there is an idle screw, but it was blocked off @ the factory. I had access to a ODP scanner at work but I really don't know much about it. I have a former background in ladder logic and CNC programming so I thought I could figure it out.
Anyway I had a chance to look at it today. Someone had popped out the plug for the idle screw hole, so I'm guessing this was an issue for the last owner.
:
Anyway I had a chance to look at it today. Someone had popped out the plug for the idle screw hole, so I'm guessing this was an issue for the last owner.
:
The previous owner on your car had an idle issue....and messed with the screw instead of fixing the real cause of the idle problem correctly. I had the same thing on my Fiero....chased an idle problem forever. Never thought to look at the minimum air screw because....drum roll please....it should be sealed. It wasn't. I reset minimum air per the FSM, and it now idles perfectly.
