GenVibe - Community for Pontiac Vibe Enthusiasts

I'm getting codes 300(random misfire), 301(misfire cyl.1), and 304(misfire cyl.4) plus a flashing CEL when it runs rough. It only runs rough and flashes between 2,500 and 3,000 RPM. I'm thinking bad gas or spark plugs. I've got 50,000 miles on the original plugs. I just put in a couple of 5 gallon jugs of gas because it's $.20/litre cheaper in Ottawa than up here but I'm sure the jugs were clean. I put in a bottle of Techron yesterday and cleaned the MAF. If that doesn't work, I'll remove the plugs and check them out. Any other ideas and reasons it would only do it in that narrow RPM range?

GT (2zz) or base/awd (1zz)? I would check the plugs first, it is semi rare but the cap things on the plugs...(grr i cant remember their names...more caffeine) they could be dirty, the coil pack!!! ha i got it. They could be dirty inside or failing.

It's a base 5 speed, header, CAI, Magnaflow exhaust. All have been installed for over a year. I've been driving some dirt roads lately so the dirt on the coil packs could be an idea. Also they may have shaken loose. I don't think it's injectors because it's only in a narrow rpm band. I hope it's not failing coil packs$$$.

It could be a few things.But that gas could be the problem too.If it's not the gas,them I would check the connection on the coil to spark plug.If all looks good,then take your plugs out and have a gander to see if they are fouled up.

Did you happen to use any dielectric grease on the plugs/coil packs when you changed plugs....Wait, re-read... 50k on the origional plugs... start there...

Are you saying dielectric grease is a good thing or a bad idea? I took out plug#1 and it didn't look too bad and the gap was nearly perfect. I also switched the coil packs around to see if the misfire moved. It still ran a little rough but not enough to trigger a CEL. When I'm in town on Thursday, I think I'll buy a set of plugs. NGK or Denso, they're both made by Denso so I can't go wrong.

Dielectric grease is a GOOD thing, it keeps the contacts from drying out. I use it every time i move an electrical connection.... It's CHEAP insurance.... I had once blown the coil end of a plug wire COMPLETELY off... My best guess is that the connection dried out and resistance went up and it started arcing, eventually it just disintegrated the metal end of the wire... I know this isn't the same issue, but it is good practice to use dielectric grease any time you have an electrical connection.... I smear it all over the top of my plugs when i do them...

Stupid question alert! So you put the grease on the electrical contact?

air, fuel and spark. Hard to troubleshoot if it is an intermittent problem thoughHave you run the car much since then, did the inector cleaner help, or are you still having the same problem? A flashing CEL is bad news, so you might not want to run it a lot if it is still misfiring.BC had a misfire CEL problem http://forums.genvibe.com/zerothread?id=27811 caused by "the rubber intake tube that runs from the stock airbox to the TB" In http://forums.genvibe.com/zerothread?id=21734 dave9382 had similar problems, but we never heard what the fix was. THey both were getting the P0171 CEL code, which you were also getting last year http://forums.genvibe.com/zerothread?id=22058 maybe these misfires are a related thing, but maybe not.

Quote, originally posted by K-NINE »Stupid question alert! So you put the grease on the electrical contact? The dielectric grease helps keep your electrical connections clean and helps prevent arcing between the contacts, it also seals out water. In the case of the spark plug and the boot, you would want to apply some inside the boot on the connector and/or to the top of the plug.

Thanks for the links joatmon. The injector cleaner hasn't really helped much. The CEL is not flashing and the misfire is not as bad but still enough to trigger the codes which I had erased with my code reader. I tried switching the coils and this had no effect. The misfire is still #1 and #4. This eliminates them from the equation. I'll try some new plugs tomorrow. It seems to misfire worse when the temperature is higher. This morning it was 68F and it ran quite well. This afternoon it was 90F and it ran like crap. The coolant temp sensor listed as a possible culprit may turn out to be the guilty party.

This is probably a stupid question but did you clean the air filter? I'm sure you checked it but I had to ask with those dusty conditions.

I'm on my second tank of gas with Techron added and the misfire is almost gone. It must have been dirty injectors. I tried to buy NGK Iridium IX or Denso's and nobody had them in stock including Canadian Tire ($48.00), Advance Auto Parts ($28.00)in Ogdensburg, NY and UAP (only Bosch and Autolite). If it's not running perfectly by the end of this tankful, I'll buy plugs.