rough idle

[aussie]

my 86 has a rough idle not to bad but annoying.have changed plugs,leads both fuel tank filters but has not eased the problem.it does not affect the running at normal speeds and even on cold starts seems to idle sweet until it comes of cold start mode.any help or input would be greatly appreciated.

 

[jeepie]

Mine had a rough idle also, I cleaned the TB and changed the plug wires, seems fine now. I am not sure which thing helped the idle, but I did find that one of the plug wires was cut where it went behind the engine, so I am guessing that was a lot of the problem. I believe it was plug wire #7.
Good luck.

 

[69MyWay]

If all else fails, check out the EGR valve. You can have a bad/leaking valve that does not show up on a diagnostic scan. The G.M. service manual provides an excellent section on trouble shooting it.

It it is the EGR, it will only get worse over time. Other than that I would think you could have some dirty injectors. Get them cleaned, then look into the EGR if it continues.

 

[GiDvEtTe84]

Try checking the distributor cap and rotor. See how fouled it is.

 

[cantdrive55]

Unlucky # 7

Mine had a rough idle also, I cleaned the TB and changed the plug wires, seems fine now. I am not sure which thing helped the idle, but I did find that one of the plug wires was cut where it went behind the engine, so I am guessing that was a lot of the problem. I believe it was plug wire #7.
Good luck.

Thats funny - with my rough idle prob the 7 cylinder was misfiring - did a tune up and found the darn plug was broke in half - and the whole thing was stripped where the plug goesin !

I have done a few things like tune up and TB/fuel injector cleaning - my idle still runs rough at stop signs after it warms up; gotta put the car in P or N - any suggests?

 

[cantdrive55]

I checked the cap and rotor -they were melted! - replaced those - I'm understanding my nect move should be to clean the EGR and IAC (in leau of replacing them)

 

[cantdrive55]

What should I troubleshoot first - the EGR or the IAC?

 

[gmjunkie]

What should I troubleshoot first - the EGR or the IAC?

I'd maybe check the temp sensor in the intake,it'll sure cause one to run just like you describe!!! Yep,it's the one below the throttle body,it's a real Joy to change!!~!!

 

[Donne Trav]

Question: Where is the EGR Valve on '94 LT1?

 

[gmjunkie]

Question: Where is the EGR Valve on '94 LT1?

At the back of the intake,large round diaphragm with a single vacuum line going to a solenoid switch under the left fuel rail cover!!

 

[LT4man]

At the back of the intake,large round diaphragm with a single vacuum line going to a solenoid switch under the left fuel rail cover!!

Is the EGR valve on an LT4 in the same place?

WHILE YOU ARE LOOKING FOR THAT, DON'T FORGET TO SAVE THE !

 

[gmjunkie]

Is the EGR valve on an LT4 in the same place?

WHILE YOU ARE LOOKING FOR THAT, DON'T FORGET TO SAVE THE !

Would be if it had one!!I ain't gonna fall for that one!!!~!!!!

 

[LT4man]

Would be if it had one!!I ain't gonna fall for that one!!!~!!!!

You must have risen early today, junk!!!

DID YOU AT LEAST TRY TO SAVE THE ?