Rough Idle
Thread Starter
Advanced
Joined: Nov 2006
Posts: 62
Likes: 0
From: Texas
Rough Idle
I need some help with this rough idle.When the car is at a stop in drive the engine tends to idle rough or I get engine shake,same thing.
But when I shift in neutral the engine smooths out. Can it be that the torque converter is not unlocking.
Any advice would be helpful.
But when I shift in neutral the engine smooths out. Can it be that the torque converter is not unlocking.
Any advice would be helpful.
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 414
From: WV
Not converter, first thing is to check your injectors with a multimeter, they should have a reading of 16.0 ohms or close to it, check them hot and cold and post your readings back here..If its not the injectors it could be the IAC (Idle air control) or a vacuam leak...My money is on the injectors, 90 had the Multec injectors that are known to have problems..WW
Last edited by WW7; Jul 13, 2009 at 09:58 AM.
Thread Starter
Advanced
Joined: Nov 2006
Posts: 62
Likes: 0
From: Texas
Not converter, first thing is to check your injectors with a multimeter, they should have a reading of 16.0 ohms or close to it, check them hot and cold and post your readings back here..If its not the injectors it could be the IAC (Idle air control) or a vacuam leak...My money is on the injectors, 90 had the Multec injectors that are known to have problems..WW
Last edited by jam019; Jul 13, 2009 at 12:15 PM.
Instructor
Joined: Aug 2002
Posts: 198
Likes: 0
From: Yucaipa CA
My '90 has a similar problem. No codes, just a moderately rough idle once everything is up to normal temperature. I appears when I stop and let the car idle after a drive. The idle will actually improve if I let it idle for a few moments. Probably a vacuum leak that appears closed loop. I have relatively new "pink" injectors. I've heard of a few methods to locate a vacuum leak on this forum such as stethoscope, smoke or starting fluid (dangerous). Which method is best?
Last edited by cash's90; Jul 13, 2009 at 06:45 PM. Reason: spelling error
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Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
How about some specs on your engine and any mods?
Whenever I have a problem, I first attack the easiest and least costly thing first. In your case I'd first eliminate the most common cause, like a vacuum leak. When checking for a vacuum leak I use plain old water. If it finds a leak, the engine idle will change and sometimes white smoke will exit the mufflers. There's your leak.
I'd also check all the vacuum hoses to be sure they're tightly connected and not leaking from years of exposure to high engine heat. Some even swell over time, resulting in a leak. Check the EGR valve for remaining open.
Next I'd pull the throttle body and remove the IAC and base plate. I'd clean the IAC pintel and all the passages of carbon buildup. I just did this to my son's 96 last night; surprising how much gunk accumulates in 13 years of driving.
I'd then check for the proper operation of the IAC by monitoring the IAC counts and how quickly they change.
I'd verify the TPS voltage using a digital volt meter.
At some point during those checks, you'll probably find the cause. Howevefr, a long duration cam or one with a tight LSA can cause what you're experiencing.
Hope this helps.
Jake
West Point ROCKS!
Whenever I have a problem, I first attack the easiest and least costly thing first. In your case I'd first eliminate the most common cause, like a vacuum leak. When checking for a vacuum leak I use plain old water. If it finds a leak, the engine idle will change and sometimes white smoke will exit the mufflers. There's your leak.
I'd also check all the vacuum hoses to be sure they're tightly connected and not leaking from years of exposure to high engine heat. Some even swell over time, resulting in a leak. Check the EGR valve for remaining open.
Next I'd pull the throttle body and remove the IAC and base plate. I'd clean the IAC pintel and all the passages of carbon buildup. I just did this to my son's 96 last night; surprising how much gunk accumulates in 13 years of driving.
I'd then check for the proper operation of the IAC by monitoring the IAC counts and how quickly they change.
I'd verify the TPS voltage using a digital volt meter.
At some point during those checks, you'll probably find the cause. Howevefr, a long duration cam or one with a tight LSA can cause what you're experiencing.
Hope this helps.
Jake
West Point ROCKS!
