i get a misfire problem after driving the car hard.

it misses even at idle, mostly on cylinders 5 and 7 (i have a scanner). but a little bit on the other cylinders, probably due to the first two missing causing a chain reaction.

i've checked all the obvious...

could bad o2 sensors be throwing it off enough to miss?

 

Be a parts replacer and find out They are supposed to be changed at like 50k anyways right? Did you use new ones with your header install? If you did the crap burning off could have fouled them.

 

hey my 94 miss fires after it warms up. I found my problem and its common in Z's. there is O ring in distributor that goes ot and letts oil up into it. causing miss fire. It seems to happen when warm after oil heats up and thins a bit. Just a idea.. i am dealing with it now :-(

 

yeah...hear ya oon the parts replacer...but at $75 each it's not easy

as for the oring thing.... exactly where is the distributer on the LT1..or LS1 for that matter

 

There is no "distributor" on the LS1. The issue with the LT1 is irrelevant to your problems.

Since you have a scanner, have you used it to look at the long term fuel corrections? Those generally start to depart from "normal" when there is a problem with the O2 sensors, or when some other problem (exhaust leaks, misfires) is causing the car to run excessively rich for example.

 

well, the LTFT seem to hover between 0 and 5%, i think on the lean side...don't recall offhand.

they too seem to fluxuate around...again, i'm not sure how much flux is normal.

the software i have is from www.obd-2.com which not many guys use...so i'mnot sure how to interpret some of the sensor data.

i'll look and see if there is a mV reading for the long term trim

 

Long term fuel trim isn't a "mV reading".... it is a percentage deviation from the "standard" fuel calculation. If its " minus" its pulling fuel out to correct a perceived rich condition, it its "plus" its adding fuel to correct a perceived lean condition. Values in the range of + or - 0 - 5% are "normal" fluctuations. You should be able to find a long term fuel trim value for both left and right sides, and there are 18 different "sets" of values corresponding to various combinations of engine load (MAP) and engine speed (RPM).

If you can generate any sort of a data log, in ".csv" format, I'd be glad to take a look at it. I also have an online guide to interpreting scan data:

http://members.aol.com/InjuneerZZ/ScanMast.htm

 

thanks fred, i actually have that guide printed out and in a binder... just couldn't find it last nite.

i can export data, but i've tried and it makes a messed up database...lots of blank fields and crap like that.

i'll see what i can do.