I've had the P0300 and occasionally P0307 code pop up and I haven't gotten around to fixing the problem, but I noticed today that my TC wouldn't lock up. If the misfire is fixed will this remedy my TC problem or am I looking at two separate problems? 2004 RCSB 2wd Mods are in sig.

 

More than likely that is your issue! Get it fixed before you do further damage. Engine misfires are you issue if I had to guess.

 

Verify the engine is not misfiring, if all checks out, you need to raise the threshold of the misfire tables. The smaller converter has a much lower rotating mass and as such the PCM "see" the now more apparent engine pulses and mistakes them as misfire. I believe the tuning guide mentions something about this issue, if it does not please let me know so I can add it....

 

I've been running the same tune for 7 months now and no issues until now. Checked everything out and turned out the spark plug was bad at least I think. It had some carbon build up on the porcelain jacket. I checked a few others they all looked good minus the carbon build up on the jacket. I'm guessing the spark plug is shorting out. I'll put a new plug in and post up.

 

After I put the plug in I still got a P0307 code. So then I swapped wires with the #5 cylinder and then I swapped coils. I still got the P0307 code. What should I do next? Compression test?

 

A compression test is a good idea, and easy to do. I'd also say to move the injector to another cylinder.

Here's a wierd one....... I chased this one around for a while before I figured it out. A partially clogged cat can throw a misfire code, and no cat codes, and no performance issues that are noticable. In my case, I kept getting a P0303. Moved everything to different cylinders, and checked compression. No trouble found anywhere, and still had the same P0303. Got a tip from an old friend, and checked backpressure. I had 3 psi backpressure on the left cat at idle, and 5 psi at 3000 rpm. Replaced the cat/y-pipe and fixed the problem.

 

That's what I did. I checked all 4 cylinders on that side. They were all about 140 psi so that made me feel better. Then I did an impedance test on the injectors and they all turned out exactly the same. I pulled the #7 injector and it was completely full of dirt. I cleaned it up and checked the others also. I put it back together and tore one of the o-rings so I couldn't drive and see if I fixed it. I'm guessing that's what was wrong.