99 Cavalier Rough Idle issue
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99 Cavalier Rough Idle issue - 12/8/2006 10:14:21 AM
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99Cavalier
Posts: 9
Joined: 12/8/2006
Status: offline
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I have a 1999 Cavalier with 2.2L and automatic. It has 121,000 (98% highway) miles. It has been very reliable and was getting about 32 miles per gallon. About a month and a half ago, besides getting brakes, they (dealer) cleaned the fuel injectors, intake, put a new fuel filter on.
Car ran great for about 2 weeks (I don't think this service has anything to do with issue, just letting you know last service). This seemed like a sudden event (fine one day, started next morning). When you start the car, it starts immediately. After a few seconds the idle gets very rough (like an older V* lope with a race cam). The engine will not stall or quit, but you can watch it shake with the hood open. After the car is warm its not as noticeable, but you feel the miss sitting a traffic lights. There is a point between the engine being cold and up to temp where you barely feel a miss.
Plugs were replaced about 20,000 miles ago, wires 60,000 miles ago. Only other parts were serpintine belt at 70,000 and an alternator a year ago.
All you have to do is barely step on the accelerator and it gets smooth. There is no jerking or hesitation when starting off and driving (even at 5 mph or more) is smooth as ever. The engine check light is NOT coming on. My mileage though is now about 28-29 mpg.
I took it back to the dealer about a week after it started to make sure one of the injectors wasn't plugged and they all checked out OK. They did a compression test and 3 were 182'ish and the 4th was 153. They thought maybe that cylinder was causing the miss (I've always heard around 140 is the low end of acceptable?). I don't agree; if it was a compression issue it wouldn't start immediately and run OK for a couple seconds,plus I don't see where it would be fine one day and do this the next. I haven't but plan to have another compression check done to see if it agrees). The other possibilyty they mentioned was a vacuum leak (but at $85 an hour to keep checking I decided not to as they had put 2 hours in it already with no answers). I decided to pursue that on my own.
I've since discovered that the 99 Cavalier (at least mine) does not have a PCV valve (its a built in air/oil seperator in the valve cover which is not plugged) and does not have an EGR valve. The local parts store had a listing for a 1999 but where they and a Haynes manual says it is there is nothing on mine. I checked with our Chevy dealer who did the work and they confirmed mine does not (surprising to me).
The problem is no worse or better, the car hasn't stalled, but I feel there has to be something that has caused the sudden issue. Can anyone offer some tips to check (since it has no PCV and EGR which often cause this type of issue I don't know where to look next).
< Message edited by 99Cavalier -- 12/8/2006 10:17:17 AM >
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Dave
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Printable Version
) is that saying its the plug wires (and to replace them)?
