high cold idle
Thread Starter
Intermediate
Joined: May 2010
Posts: 31
Likes: 0
From: new hartford new york
high cold idle
looking for some insight on how ecm controls cold idle. idle before reaching operating temperature is 1500rpm. warm idle 700 rpm. all typical problems have been counted out. no codes, no vac leaks, timing at 6degrees btc, throttle bodies rebushed,synchronized with mannometer, all new sensors,tps at .530, fuel press at 14psi, new injectors. i have had this car for a while and have never figured this problem out. it never changes worse or better, just annoying to have to sit in my car for 4 or 5 minutes before i can drive anywhere. the only thing i have noticed is that if i disconnect computer for 1/2 hr or hour (when i am checking base idle, iac's disconnected and plugged)that when i restart (cold), it only idles at 800rpm until warm. any ideas would be greatly welcomed. just to cover a few bases, i have replaced coolant temp sensor(ecm), oxygen sensor, iac's, tps,map sensor, all new gaskets and vac lines.
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
looking for some insight on how ecm controls cold idle. idle before reaching operating temperature is 1500rpm. warm idle 700 rpm. all typical problems have been counted out. no codes, no vac leaks, timing at 6degrees btc, throttle bodies rebushed,synchronized with mannometer, all new sensors,tps at .530, fuel press at 14psi, new injectors. i have had this car for a while and have never figured this problem out. it never changes worse or better, just annoying to have to sit in my car for 4 or 5 minutes before i can drive anywhere. the only thing i have noticed is that if i disconnect computer for 1/2 hr or hour (when i am checking base idle, iac's disconnected and plugged)that when i restart (cold), it only idles at 800rpm until warm. any ideas would be greatly welcomed. just to cover a few bases, i have replaced coolant temp sensor(ecm), oxygen sensor, iac's, tps,map sensor, all new gaskets and vac lines.
I think the 800 rpm idle after disconnecting the computer may be due to the ecm's memory being wiped out and resetting it. it has to 'learn' the engine again after it is reconnected.
Rick B.
Thread Starter
Intermediate
Joined: May 2010
Posts: 31
Likes: 0
From: new hartford new york
high idle
if i try to put it in gear when cold( high idle) it will bang into gear, and be hard to stop/slow down. i'm just saying that the car couldnt have idled this high when it was new or no one would have bought it.
Instructor
Joined: Jul 2007
Posts: 130
Likes: 3
From: Goshen IN
Once it idles down, does it stay there? I have the same problem. But when I drive it, sometimes when I stop, it will idle OK and the next stop it will not go below 1200. What would make be so sporatic? Does yours do that?
Pro
Joined: Jul 2008
Posts: 699
Likes: 3
From: Millersville, MD
That sounds pretty normal to me for a computer controlled engine. All of my family's daily drivers idle higher when cold, as does my LS1. I believe it's for emissions purposes. I don't see why you have to wait 4 or 5 minutes before driving. As soon as the oil pressure is up you should be good to go. In fact driving sooner will help the engine to warm up faster and bring the idle down.
I think the 800 rpm idle after disconnecting the computer may be due to the ecm's memory being wiped out and resetting it. it has to 'learn' the engine again after it is reconnected.
Rick B.
I think the 800 rpm idle after disconnecting the computer may be due to the ecm's memory being wiped out and resetting it. it has to 'learn' the engine again after it is reconnected.
Rick B.
Le Mans Master
Joined: Apr 2001
Posts: 5,000
Likes: 1
From: Minneapolis, Mn USA
82 will cold idle way too high if there is a vacuum leak, or if your Coolant Temp Sensor is aged.
Check for vacuum leaks at the TB bases, intake manifold upper gasket area at the edges of the top plate, and any vacuum hoses-fittings.
Replaced the CTS at the front of the manifold. Get the new 84 style with better weather proof connector with wiring pigtail included.
Look to see if your throttle body screws setting look tampered with or does everything look untouched? It is important to not have anything tampered with from the factory as this will usually screw up the operation, not "fix" it. Bubba doesn't know how to make the CFI run correctly.
I fixed mine with new intake manifold gaskets ( from doing a CFI ported manifold job) and a new CTS. It ran excellent after that.
Good luck
Check for vacuum leaks at the TB bases, intake manifold upper gasket area at the edges of the top plate, and any vacuum hoses-fittings.
Replaced the CTS at the front of the manifold. Get the new 84 style with better weather proof connector with wiring pigtail included.
Look to see if your throttle body screws setting look tampered with or does everything look untouched? It is important to not have anything tampered with from the factory as this will usually screw up the operation, not "fix" it. Bubba doesn't know how to make the CFI run correctly.
I fixed mine with new intake manifold gaskets ( from doing a CFI ported manifold job) and a new CTS. It ran excellent after that.
Good luck
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