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I have a 92 vert. It sits more than gets used. My work truck is down at the moment so I have been using my vette the past few weeks. It has plenty of power but idles very rough. When I am at a red light the car actually shakes me around a bit.
I'm not afraid to turn a wrench but honestly I need help. I have no idea where to even begin. If it were my old C3 I would be able to know where to start trouble shooting but I am at a loss here. No carb adjustments on this rascal. I have a fresh tank of gas in it since using it again. Can't help but think I may need to replace a sensor but which one?
Any guidance that you can offer would be greatly appreciated.
Vacuum leaks: vacuum T under right injector cover. Near battery and ASR actuator. Carbon build up, clean throttle bores. Drive about 5 miles at 2k rpm or more.
Could be a vacuum leak like Kevova said also try cleaning the throttle body bores and Idle Air Control Valve with CRC cleaner both get gunked up with carbon
You can also just try replacing the valve as they are about $75 as sometimes cleaning doesn’t fix the problem 27 year old parts like that you can always just look at it as a preventive measure if it doesn’t totally fix the current problem...
Last edited by Y-bodluvr; Apr 5, 2019 at 09:56 AM.
Could be a vacuum leak like Kevova said also try cleaning the throttle body bores and Idle Air Control Valve with CRC cleaner both get gunked up with carbon
Thank you everyone for taking the time to replay. I appreciate the help. It's funny sometimes you cant see the forrest through the trees. If anyone would of asked me I would off said check for vacuum leaks then plugs and wires. ( not even sure if the opti spark has a cap and rotor like old disdributors) Last year when my son's 79 vette was idling rough while it was in my driveway I had hime pop the hoods and I found a vacuum leak and it fixed it. If my 92 vette was my other car 69El Camino I would know what to do. I guess it the whole injection intake plus sensors that make me unsure of what to do as I have little expiernce with them. Dad didn't teach me anythng about these as they woren't arought when I was shadowing him and learning. He did show me how to tune a carb by ear or with a tach.
If it's nice outside tomorrow and the wife doesn't have plans for me I will spend some time under the hood and see if I can come up with anything.
Thanks again.
Last edited by superdave269; Apr 6, 2019 at 08:48 PM.
Absolutely.. always K.I.S.S. first, then go to the next level of troubleshooting. When is the last time you did a full tune up to the car? Fuel filter also... Start there.
I remember years ago, my old business partner bought an 87 Coupe. Ran well on the highway and plenty of power.... at a stop light, the engine would shake like hell... Turned out to be one of the plug wires I think it was #7, was not snapped onto the plug as it should be and sitting back off the plug a bit.
All good suggestions, and really a lot of Maintenance Items. There is no reason to not clean the throttle body and IAC passage. It can't hurt. It is also never bad to start with checking vacuum lines. Just good general maintenance. Same for plugs and wires, unless you verify they are in good shape.
Fuel Injection or not, some things never change. You need Air, Fuel, and a timed spark.
Pull your plugs and read them. If one looks sooty, you may have a sticking injector.
As mentioned above, got any codes? Hate to tell you, but stumbling idle can be the opti (yes it does have a rotor inside of it, but this isn't like what you are thinking where you can just replace them. Pre 95 cars were more prone to failure since they were not vented.
I would add to also check fuel pressure at idle. Another "free" check.
Post back up your findings and we can go from there.
More great advise.. What a great forum!
I actually was wondering if I had a bad wire. A coupe of years ago my truck was running bad so I figured time for a tune up. Bought the normal things, cap , rotor, plugs, wires. As soon as I took off the cap I spotted a bad wire. Easy fix.
Dad always said "all I need is fuel an spark and I can make anything run" So we always started by pulling a plug to check for spark.
I did the spray bottle check to look for leaks On Sunday. I didn't find any/ Then I pulled the IAC and cleaned it. It was full of carbon as suggested. I haven't had time to give it a good test drive but will later today to see if if this help
Thanks again everyone.
This is why I suggested cleaning or replacing the IAC valve...if the car is making good power it means it’s firing on all 8 the car will still run good with a gunked up IAC but WONT idle smooth if the plugs wires or Opti is bad You will know it It still won’t hurt to change the plugs and wires especially if they haven’t been replaced in a while they can only smooth the idle more and make it run better
1992 idles rough Where do I start looking?
