Rough Idle
Thread Starter
1st Gear
Joined: Oct 2008
Posts: 1
Likes: 0
Rough Idle
hi, I barely got my 2nd corvette and it has a fairly rough Idle. It is a 1991 six speed. Sometimes it doesnt want to turn on, this only happens when the engine gets hot, it acts like it has no gas. Then wen I leave it alone for about fifteen minutes it starts right up. Some times wen I am at a redlight I have to be careful to not rev the RPM's because that could cause the engine to turn off. Also I know that my corvette is supposed to have alot more torque and it just seems like the timing might be off. My friend told me he had a similar problem and he ended up spending hundreds on replacing injectors and other things and wen none of that worked he just replaced the computer and that fixed everything. I am going to borrow his computer because he has like two of them and see if that works but I am still not sure if it will work. I also checked the injectors and it seems like not all of them are working or not working as much as the others... that is weird because I know that they are all connected through the same wire. I read the thread about replacing injectors. Has anyone had the same problem?
Burning Brakes
Joined: Jan 2007
Posts: 853
Likes: 0
From: Slinger WI
Injectors have been thouroghly discussed numerous times on the forum, do a search. I would also do a search about the opti ignition also. I would also search and read about the numerous posts about testing injectors.
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
I would start the the cheapest easiest stuff first. Plugs,wires,cap & rotor. I believe the H.E.I. caps are fairly inexpensive unlike my opti. Perhaps the coil while you're there.
You can get a mechanics stethescope for around $8-$10. Use this to listen to the injectors. You will be able to hear if they are not functioning. You will also probably find some evidence of injector failure when you change the plugs.
It may also be something as simple as putting some "Seafoam" or other injector cleaner.
But you have a good plan in swapping the ecm since it won't cost anything. Can't hurt.
You can get a mechanics stethescope for around $8-$10. Use this to listen to the injectors. You will be able to hear if they are not functioning. You will also probably find some evidence of injector failure when you change the plugs.
It may also be something as simple as putting some "Seafoam" or other injector cleaner.
But you have a good plan in swapping the ecm since it won't cost anything. Can't hurt.
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
If you have the stock Multec injectors in the 1991 L98 engine, I DO NOT recommend that you add ANY fuel injector cleaner to the fuel tank. GM issued a service bulletin (warning) in the early 1990's to advise customers not to do this practice as it can damage the coils inside the Multec injectors. IF you have bad injectors, you can buy remanufactured 22 pounders from FIC (note thread at top of tech page) at a reasonable price. The installation process is not difficult. I have a Word document on injector repalcement and do not mind sharing it with you. Send me an email if you want a copy. Here is a photo illustrating the appearance of the 89 - 91 GM Multec injectors.
Keep searching for the root cause of your problem! Once you find and solve the problem, the result is well worth the effort
Keep searching for the root cause of your problem! Once you find and solve the problem, the result is well worth the effort
