Idle and misfire problems

[ramman1505]

OK everyone, so here's the deal. I just recently replaced my rear O2 sensor bc I had a CEL for it. Now before replacing it i was getting a misfire at full boost 13psi. As time went on the misfire started occurring earlier 12psi then 10 then 8 psi and so on. Eventually I was even starting to have erratic idling and a sight misfire at idle. The only code I ever got was bank 1 sensor 2 O2 malfunction. So I replaced it and it didn't make any difference. So i replaced the spark plugs and the misfire went away and I was able to boost 13psi without a misfire. However now all the symptoms are coming back again. It does not feel like fuel cut at high boost, it feels like just a cylinder misfiring repeatedly then clearing up once the pedal is released. When the misfire occurs it sounds like a automatic gun going off. Whatever plug is missing it doesn't just miss once, it misses repeatedly until i leave off the gas. Now the other day I was pulling out and lost all power and the motor seemed to be running on only 2 cylinders, then it cleared up and ran good. It almost seems like one of my coil packs are giving out on me or some sensor somewhere is messed up. Has anyone ever experienced this before? Any ideas what to tackle next? Thanks guys

 

[shockersTalon]

The rear o2 sensor only tells your pcm that the the cat is doing its job thats all. It does sound like an ignition misfire due to its backfiring. There is alot that happens to send the spark at the correct time that you realy need to have a scan tool to read. If you have access to one hook it up and data log the event and see what readings incorrect.

 

[thatblondechik]

^^
Sorry, Kid. But you've forced me to call BS on you as well.

Obviously it's an ignition misfire...that's what a misfire is. Could be as simple as a bad plug, could be a shotty coil, could be your CAS, hell your timing could even be off.

Try searching your issue, here's a couple to get you started:

http://www.dsmtuners.com/forums/newbie-forum/265679-misfire-wits-end.html

http://www.dsmtuners.com/forums/han...k-stutter-etc.html?highlight=misfire+throttle

 

[92_6bolt_1290]

find out what cylinder(s) are misfiring then take a look at the spark plugs and check the resistance of all the plug wires. if your plugs aren't getting fouled and your plug wires have a good couple thousand ohms of resistance then a coil pack it most likely is

 

[cabbageman97]

It would only be a coil if you have two cylinders misfiring. We use a "waste spark" ignition set-up. Its very rare to have our type of ignition system and only have a single cylinder misfire from a bad coil. It sounds like fouled plugs. AFR's could have been so off for awhile then now you have the o2s back working, you probably just cooked them. Clean and regap them, 0.031" I believe it might be. But check which cylinder(s) are misfiring first and foremost.

 

[shockersTalon]

A missfire can also be caused by bad engine internals, incorrect sensor readout, or a bad injector. Not just an ignition isuue. There is such a broad range of problems that could cause this issue you realy need a scanner or 5 gas and know how to read the results otherwise youir just changin parts.