I have a 2002 zr2 with a 4.3 The engine light was on and code said misfire. i changed the plugs, wires cap and rotor. Also checked compression on all cylinders when I did the tune up. The light went off for about 3 days. no it comes on intermitently usually is off at idle, once you start to drive and get up to about 30mph the light comes back on and will flash. code now reads random/multiple misfire. Any idea of where to go with this? anyone have a similiar problem? Also not sure if it is normal for these 4.3's but the oil pressure (when hot) will drop down to around 5-10 at idle and then up to about 40 when you are driving. Im sure the miss fire could be effecting some of that. It looks like the sending unit was replaced by a previous owner and the plugs/wires looked fairly new. I think I may be chasing the same problems the previous owner was chasing...lol Any help you be appreciated.
Thanks Dana,
I got everything from autozone and got the cheaper stuff. they had like 3 different prices for different brands etc. You think that could be part of it? I had another guy say that the cheap wires may be the cause.
oh also right after I did the tune up if you hammered it and put the truck under a load you could hear a fast ticking. (spark/arching sound) I thought it may just be a spark nock. but when it was doing that it never threw any codes. And I have not heard it since. When I did the tune up I put di-electric grease on the inside of the wires to help keep out moisture.
Check you distributer for play up, down, side to side, and check for slop. Easiest way is to just pull it and check the gear as its only one bolt. I went through the entire ignition system looking for my miss fire, and found a worn distributor gear to be my problem.
I can't tell you how many times ive installed autozone ignition parts and had to redo the job cause the parts are junk.. Toss in some delco plugs and some car quest wires rotor and cap. and i'd bet your problem goes away
Shit ill throw 5k casino cash on this bet :sonicjay:
Ok I have delco plugs. Wires are Duralast and the cap/ rotor are truegrade. I put a coil on it this weekend. it runs strong. but light still comes on. I think I might replace the cap/rotor and wires and see what that does. if thats not it I think it might be the Cat.
I just read something that the belt tensioner pulley could cause this??? Mine has a bit of movement in it. (moves about 1/4" while it is running) This sounds very strange to me but could the random misfire have anything to do with the belt tensioner being bad?
well yes in a way...
the reason is the motor has a knock sensor (spark knock)and the rattle of the tension pully can cause the computer to retard the timing.. in theory that is ....
un plug the sensor it is on the drivers side of the motor by the center cyl..
sounds strange but what the heck wont cost anything to try this
Well for starters whoever told u it could be the belt tensioner is a retard and I've had this issue with a bout a half dozen customer vehicals and every time I fixed it by installing a new distributor
i agree with toyfish, these are known for bad distributors and have no adjustment, also autozone ignition parts are trash. ive done maintence tune ups with zone shit and they ran worse than when it came in.... put delco plugs in it, delphi cap and rotor and a good set of wires, more than likely you will need a distributor also, pull it and check for gear wear on the distributor gear.
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