Questions and Answers
S-10 Idles Rough
Q. I have a 1990 Chevrolet S-10 pick-up. 4.3 litter, auto transmission, 88,000 miles, fuel injection, P/S, A/C. The problem is a rough idle. Worse as the engine heats up and the idle drops. I had a complete tune-up at a dealer. I was told it is caused by low compression. 105 - 85 were the high and low readings. I don't feel is that high of mileage to have this problem. The problem started a couple months ago. I bought the truck with about 43,000 miles on it and changed oil every 3 months, 5W30 oil, major brand. ( less than 3,000 miles each time). I welcome your thoughts on this.
Thanks for your time,
BillA. You need to determine what is causing the low compression. I'm assuming they did not do a wet compression test. If they did, they would be able to tell if the problem is rings or valves.
I would hazard to guess that you never had the valves adjusted on that engine. Tight valves would account for the low compression. The wet compression test would confirm this. I would recommend getting the valves adjusted and then redo the compression test. I think you'll find it will increase and run a lot smoother.
