Originally Posted by MikeGyver

I can't guess what your problem is from the info that scan an config shows (not that I could otherwise ), but it makes me wonder what your fuel pressure and ignition advance are like.

Originally Posted by TXjeepTJ

here you go, the voltage does drop quit a bit (down to 12v) but I don't really see a relation to the misfires

you can see in one part I hold the rev at about 3k and all the misfires go away

The "misfire history" on this truck is ridiculous... every cylinder has over 800 misfires lol

Originally Posted by Suburbazine

Voltage drop will cause all sorts of unexpected failures. Everything from the fuel pump to the ignition coils are affected by a voltage drop, considering they are designed to run at 13.5-14.5 volts. Also, if your alternator is failing to keep up, it will cause some unbelievable electrical noise which the interference canceler (if equipped) cannot suppress.

I'd say get some jumper cables and borrow power from another running vehicle and see what happens with your voltages and rough running concerns.

Originally Posted by TXjeepTJ

My fuel pressure is pretty high, 60-65 psi when not in boost. Idk why it is so high

want me to post up a scan of the ignition advance? or any other values that could help you determine a place I should start looking?


If you look at the oxygen sensor info, the bank1 seems to go crazy, which then the bank2 starts to follow it. Could my bank1 sensor be bad at a low flow rate going across it (at idle) and then bank 2 tries to follow it thus resulting in bad afr/misfiring

Originally Posted by TXjeepTJ

yeah, when the rough idle starts it goes down to about 12 then shoots up to a little over 15 while it idles rough. Then as it straightens itself out it goes back to 14.6-14.8

Could my spark plugs be causing this? NGK TR6 set to .035, unless I set them wrong

edit: I guess it couldn't be my spark plugs if it wants to run lean under the rough idle condition/misfires.. if plugs weren't firing it would cause it to go rich, right? unless the computer sees that first 12afr (from plugs not firing) and immediately cuts off fuel creating the lean misfires

Originally Posted by Wilde Racing

I just looked at your tune, is it Nelson or yours? What injectors? offset? The LT fuel trims want a ton of fuel... If this all started at the time of your FI install I would bet injector tuning...

Originally Posted by TXjeepTJ

good idea! actually the other week I was driving and electrical noise starting going through the speakers (if that is what you were talking about). Your idea will rule out the alternator being the problem, thanks!