greaseman69

I already made a thread in another forum section but I figured I might get more detailed help here. My car started misfiring after a few races with my buddy, I noticed it when my car started shaking real bad at highway speeds when I gave it any throttle (this is immediately after racing). The car holds a steady idle but I think you can tell it's still misfiring a little, some vibration but I'm not certain. Its mostly only noticeable when giving it over 50% throttle.

I very recently installed 1 7/8 headers (plus all emissions deleted), true duals, NGK TR55 plugs, MSD wires, and bosch 13111 O2 sensors. I checked all of this and it seems fine. The metal lip right after the threads of the plugs are black with carbon but I think this is normal. Plugs and wires are tight and secure. Fuel pressure is a strong 58 PSI at idle.
Here are all my codes:
P0140
P0160
P0405
P0412
P1133
P1153
P0300
I know most of these are just from removing emissions but what about P1133 and P1153? Apparently those are common with LTs, but could they be related to the misfire?

Also, last night I reset the PCM and it ran beautifully, thought I fixed it. This morning the misfire came back. Does this indicate anything? Could a tune fix it? Thanks in advance, I have no idea what to do.
2000 trans am btw

Tyler Dietzenbach

iTrader: (5)

I'm about to install 1 7/8 headers, ORY, NGK TR55 plugs, MSD wires, and O2 sensor extensions. Also removing emissions. Following just in case....

Tyler Dietzenbach

iTrader: (5)

I would like to add that I know that the rear 02s dont change any kind of tables. So it can't be those. It COULD be that the Bosch(s) are causing issues.

Tyler Dietzenbach

iTrader: (5)

And lastly since you have multiple misfire that means that OVER one cylinder has a problem. So if it was related to your upgrades than it could mean any of the following:
2+ plugs are bad
2+ wires are bad
Or one of each or more are bad

Since you have 2+ cylinders missing.

I find this the least likely but you never know. I've seen plugs come with hairline cracks before. Only way to know for sure is to test.

greaseman69

based on advice in the other thread I made I think I'm gonna go with a mail order tune and fresh plugs. My car is probably just running stupid rich right now, we'll see if it helps. If not...I have a nice tune to look forward to when I fix the misfire