Surging idle on an 89
Thread Starter
Drifting
Joined: Aug 2002
Posts: 1,890
Likes: 1
From: Bismarck North Dakota
Surging idle on an 89
Car = 1989 convertible, bone stock, auto trans. 44,000 miles.
I will be driving at normal city speeds when I can feel the car surging. Not like the clutch type torque converter surge, this is the engine. When I slow down to stop at a light, the car will almost stall when the computer kicks the idle up. Then when the idle goes back down to 600 RPM, it starts to surge back and forth between 6 and 700 RPM. If I sit long enough at a light, the idle will drop down to below 500 again before the computer kicks up the idle to 1200. When I park, the car will surge between 600 and 700 until I shut down.
If I hold the pedal down and hold the RPMs around 1200, I can hear a slight miss. I hear a small tap that coinsides with the miss.
Blown engine? Bad sensor? Bad injector? Any ideas and how much $$$? The car is parked until I can figure this out.
Thanx.
I will be driving at normal city speeds when I can feel the car surging. Not like the clutch type torque converter surge, this is the engine. When I slow down to stop at a light, the car will almost stall when the computer kicks the idle up. Then when the idle goes back down to 600 RPM, it starts to surge back and forth between 6 and 700 RPM. If I sit long enough at a light, the idle will drop down to below 500 again before the computer kicks up the idle to 1200. When I park, the car will surge between 600 and 700 until I shut down.
If I hold the pedal down and hold the RPMs around 1200, I can hear a slight miss. I hear a small tap that coinsides with the miss.
Blown engine? Bad sensor? Bad injector? Any ideas and how much $$$? The car is parked until I can figure this out.
Thanx.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Surging idle on an 89 (rainsux89)
It could be a number of things.
You could start by pulling the spark plugs to see if all are in good shape.
Check for any splig vacuum hoses and hard plastic tubing.
At night check to see if any wires are arching and inspect them for any burn or arching marks.
Pull the dist cap to check for carbon tracks inside the cap and wear of the rotor.
Since the miss is regular, clip a timing light onto each plug wire in turn and see if the miss coincides with missing light flashes. I used this method to locate a bad dist cap terminal.
Get some intake cleaner and clean the TB plates and bore; then clean and set the IAC under the TB (method on my site).
You could start by pulling the spark plugs to see if all are in good shape.
Check for any splig vacuum hoses and hard plastic tubing.
At night check to see if any wires are arching and inspect them for any burn or arching marks.
Pull the dist cap to check for carbon tracks inside the cap and wear of the rotor.
Since the miss is regular, clip a timing light onto each plug wire in turn and see if the miss coincides with missing light flashes. I used this method to locate a bad dist cap terminal.
Get some intake cleaner and clean the TB plates and bore; then clean and set the IAC under the TB (method on my site).
Burning Brakes
Joined: May 1999
Posts: 1,179
Likes: 0
From: waller texas
Cruise-In I Veteran
Re: Surging idle on an 89 (65Z01)
That also sounds like an egr valve failing.shoot some carb cleaner or wd40 on the egr.If it speeds up then that means egr leaking and causing surge and eratic idle.
Safety Car
Joined: Feb 2000
Posts: 4,564
Likes: 110
From: Austin Texas
Re: Surging idle on an 89 (rainsux89)
Boy, have I been HERE before.....
The symptom points to the ICS (Idle Control Solenoid) on the throttle-body.
I had my car for less than 2 years brand new and this was the same exact symptom I had. I took it to the dealer 4 times and it never would do it for them. I took it to the club meeting and one of our racing members overheard me telling the story, took me to the car and we started it. He heard the problem, pointed to the solenoid and said "that's the problem...tell them to replace it."
Dealer replaced it and the problem was gone.
There MAY be some carbon build-up in the seat of the solenoid as well. Replace the solenoid, clean the inside with carb cleaner and it should work fine.
[Modified by Joe90, 8:35 AM 9/4/2002]
The symptom points to the ICS (Idle Control Solenoid) on the throttle-body.
I had my car for less than 2 years brand new and this was the same exact symptom I had. I took it to the dealer 4 times and it never would do it for them. I took it to the club meeting and one of our racing members overheard me telling the story, took me to the car and we started it. He heard the problem, pointed to the solenoid and said "that's the problem...tell them to replace it."
Dealer replaced it and the problem was gone.
There MAY be some carbon build-up in the seat of the solenoid as well. Replace the solenoid, clean the inside with carb cleaner and it should work fine.
[Modified by Joe90, 8:35 AM 9/4/2002]
