Been trying to get my car working 100%, I'm getting close. This is one of the few problems left with it. And before anyone says OPTI, I put a new one it didn't help.

At idle, when the car is heat soaked, I will get a slight miss and rough idle. This doesn't happen when the car is cold. Pretty much any other time it runs strong, I will get a slight miss sometimes when starting off in 1st off idle(again only when hot)

I have a scanner, no codes. MAP and MAF are steady, IAC is good. Vacuum is also good as well as fuel pressure. Also, car doesn't pull any timing(disabled knock retard). Hmm, coolant temp sensor good, IAT reading normal, TPS steady, I can't find anything out of the ordinary here.

I unplugged BOTH o2's to force open loop, car still has the slight miss.

Am I correct to assume the problem is plugs/wires?? I've already changed the plugs and wires once already.

Can wires/plugs perform "worse" or have a higher chance of arching when they are hot??

I just don't know what else it can be, it's intermittent at times and again only when the engine is warmed up and heat soaked. I would think a bad plug or wire you'd get the problem all the time.

Any suggestions of what else it could be?

Thanks
Brian

 

You know I have the same problem too but I think mine has more to do with the O2's. I know both of mine are bad because I always get the "slow responce" code for both of them occasionally. It also may not be my O2's. Let us know if you find anything out!

 

I wish I had your problem, seems alot easier to diagnose. For yours, go pull both o2 sensor harness's so your car is running without o2's. THen if the car runs good(no missing), you know you have a bad sensor OR bad wiring to the sensor. If your car still misses, it's not the o2's and your in my spot, haha

Brian

 

I'd bet it was wires. Electrical conductivity lowers with temperature. I once had a bunrt wire which didnt affect anything until after the car was running for about a minute and warmed up.

I'd check all of the wires over again.

 

THanks for the replies.

I ordered some new heat shielded wires and new plugs just in case.

Brian