rough idling question
Thread Starter
Heel & Toe
Joined: Mar 2004
Posts: 23
Likes: 0
From: Columbia SC
rough idling question
My son is bringing his Vett over to have me look at it. He says it is running rough at idle and smoothes out when driving. I was wondering if this 91 Vett 350 V8 had oxygen sensors I know they have never been replaced if they do. I also am thinking plugs he has not had them changed for 100,000 miles he thinks. I would like any thought and help if someone else has had this rough idling problem.
Instructor
Joined: Apr 2003
Posts: 148
Likes: 0
From: Lakwood N.J.
I had the same problem with my 89. It turned out to be the injectors. I'm no expert, and I'm not saying it is the injectors, but I would check them. My car ran fine, but the idle was horrible. While on a long drive on the turnpike, after about 40 miles of 70 mph driving, the car finally stop running. Check the impedence of each injector. They should all be very close. My 89 was supposed to be around 14.5. I had 2 @ 14.5, 2 @ 19.3, 1 @ 20.4, and 2 @ 5. After changing the injectors, the car runs and idles fine. Before I checked the injectors, I checked the fuel pressure, and volume. Cleaned the MAF, changed both MAF relays, checked the TPS. It turned out to be the injectors. I hope this helps. PS, I also changed the ECU, I had too. Driving the car on that long drive with the bad injectors fried the ECU.
Racer
Joined: May 2006
Posts: 283
Likes: 0
From: Pace Florida
I had the same problem with my 89. It turned out to be the injectors. I'm no expert, and I'm not saying it is the injectors, but I would check them. My car ran fine, but the idle was horrible. While on a long drive on the turnpike, after about 40 miles of 70 mph driving, the car finally stop running. Check the impedence of each injector. They should all be very close. My 89 was supposed to be around 14.5. I had 2 @ 14.5, 2 @ 19.3, 1 @ 20.4, and 2 @ 5. After changing the injectors, the car runs and idles fine. Before I checked the injectors, I checked the fuel pressure, and volume. Cleaned the MAF, changed both MAF relays, checked the TPS. It turned out to be the injectors. I hope this helps. PS, I also changed the ECU, I had too. Driving the car on that long drive with the bad injectors fried the ECU.
Safety Car
Joined: Dec 2007
Posts: 3,616
Likes: 5
From: Sandhills of North Carolina
I had the same problem with idle and it was/is a couple of things.
I need plugs/wires. One plug has a intermittent skip.
But the biggie was the IAC. I was getting a engine surge evey time the AC compressor would cycle on and off and especially with the cruse on. Replaced that and idles much better now. And no more surgeing.
But it could be any number of things in your case. You just have to eliminate them one at the time.
I need plugs/wires. One plug has a intermittent skip.
But the biggie was the IAC. I was getting a engine surge evey time the AC compressor would cycle on and off and especially with the cruse on. Replaced that and idles much better now. And no more surgeing.
But it could be any number of things in your case. You just have to eliminate them one at the time.
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Racer
Joined: May 2006
Posts: 283
Likes: 0
From: Pace Florida
FICI Thank you very much for the video post. I am going to check mine asap. rddaves that is a short or dirty contact in the controller. Mine does it once it a blue moon and one day I will need to address it.
