Had a misfire ever since I bought my car.

Here's a little history about the car:

It has headers, y pipe with a magnaflow muffler, deleted cats and deleted rear 02's, bored TB and deleted TB coolant lines as far as I can see. I dont know if it has a cam upgrade or if it's been tuned or not. I changed to NGK G-power with pre gapped at .60. Could an inpropper gap cause this misfire?

The LTFT and STFT are within 5%, no CEL codes except for my fan wiring circuit since my fan does not come on so I use a switch for now, the IAT wiring was broken so I used a jumper wire and it works now, still cant find where its broken, the rest of the sensors look within specs on my scanner, on the misfire count its showing cyl 1, 5 and 8 misfiring. I swapped the plugs, wires and coils around with no change. The 02 data is a little funny, but my guess is because of the misfire. There are resistors or somthing in the rear 02 wiring to keep the codes from setting the CEL i guess, one might have failed as im getting a flat line on my Bank 1 Sensor 2. I have a ignition spark tested I need to use, I tried it on cyl 1 and it appeared to have a weak inconsistant spark when tested at 20KV but I will have to try again to confirm that.
I changed the fuel filter, spark plugs, wires, front 02's, cleaned the major sensors and EGR, oil and coolant change, new air filter and sea foamed. Spark plugs look clean and all look similar, maybe running a bit lean. The 02's were pretty clean too. Exhaust smoke is white, smells a bit from the deleted cats..

I am almost ready to rule out spark at this point, but I might change back to copper just to make sure of that.

Here are pics of the raw data and pending codes: https://picasaweb.google.com/1121999...80100972155842

Now that my scanner has the misfires pin pointed to the cylinders I am determined to get this figured out.

 

well a misfire can be a lot of things, down out my shop ive seen bad injectors, and vacuum leaks, so you should check those.

 

i had a missfire with the back 2 cylinder in my 199 camaro 3.8l. the cause was the ignition control computer under the coils. i am not sure if the z28s have the same coilsetup tho. it ended up being a $150 part

 

In most cases three things can cause misfires: ignition problems, wrong A/F mixture, low compression. Try to isolate the problem to one of those items, and then look for a fix. IMO the 0.060" plug gap is excessive and could be part of your problem. The multiple misfire code you showed is usually cause by a lean fuel mixture, so a fuel pressure test may be a good idea. The white smoke you mentioned, if it is billowing out, is an indication of coolant getting into the combustion chamber, and that will also cause misfire.

 

The STFT and LTFT are showing a bit lean, but still under 10% normally.
I am going to switch the plugs back to TR55 with a .55 gap, I just have a hunch it could be my issue.
It's not blowing excessive white smoke, I think it may just be burning off water vaopur since it's cold out now.
Will a fuel pressure tester find clogged or stuck fuel injectors? I find it odd that cylinders 1,3,5, and 8 are misfiring, but 2,4, and 6 have never had a misfire in the misfire history.

 

The fuel pressure test won't identify a bad injector, it only checks the availability of fuel to the injectors. However make sure the injector "O" rings are sealing tightly as air flowing through the rings will mess up the A/F ratio. The best way would be to remove the injectors and send them out to be cleaned and flow tested. Otherwise you can get them professionally cleaned while still on the engine, but if the injector is completely clogged this procedure won't help much. You could also add a dedicated injector cleaner to the fuel tank and hope it does something.

 

I will change out the spark plug, wire, coil and fuel injector one at a time with the cylinder that is misfiring to the cylinder that has never had a misfire. This should be a surefire way to find out what the problem is.