Gentlemen My mechanic has tried everything short of pulling the heads off. My PO300 engine code will not go away. I have a 2006 H2 SUT with 157k miles on it. I'm the only owner. It is misfiring on the left side only particularly the 1st and 7th with only 160 psi. We have changed the spark plugs, wires, PCN, PCN hose intake gasket, and it past a compression test. We even followed someones advice and did a crank relearn and cleaned the MAF sensor. The engine warning light is always on and some times blinks. My drive around town gas mileage has gone from 12MPG to 8MPG. My mechanic is affraid that I could mess up the catalytic converter if I do not figure it out soon. If I take it to the dealership they are just going to say do a tune up which we have already done. PLEASE does someone have any ideas?

 

Simple stuff first(no tools required):

 

MOVED for you. Welcome to HF.

Please READ before you post, as the HF Help & Suggestion Center says in the top Sticky Thread.... " Do NOT post vehicle questions in this section" as it is for questions on how to use forum features and has nothing to do with any vehicle.

All H2 SUT questions should go in the H2 SUT section, or even the H2 section when dealing with common things, like engine and trans issues, etc..... The H2 section has more activity.

 

Have you replaced the coil packs? I had a similar issue with my 07 SUT and I found the 7 & 8 packs going bad. I replaced all of them and the two harnesses and it solved the problem. I hope this helps!




QUOTE=TAPTEXAS;368804]Gentlemen My mechanic has tried everything short of pulling the heads off. My PO300 engine code will not go away. I have a 2006 H2 SUT with 157k miles on it. I'm the only owner. It is misfiring on the left side only particularly the 1st and 7th with only 160 psi. We have changed the spark plugs, wires, PCN, PCN hose intake gasket, and it past a compression test. We even followed someones advice and did a crank relearn and cleaned the MAF sensor. The engine warning light is always on and some times blinks. My drive around town gas mileage has gone from 12MPG to 8MPG. My mechanic is affraid that I could mess up the catalytic converter if I do not figure it out soon. If I take it to the dealership they are just going to say do a tune up which we have already done. PLEASE does someone have any ideas?[/QUOTE]

 

I can not thank everyone enough for all of your advice. It lead me to the solution which was the left side of the catalytic converter was pretty gunked up. It is great to have it running normal again. Thank you all!

 

gunked up in what way?

 

That's just what they said. Maybe not "gunked" but that was the point. If it is important I can ask the mechanic that installed the new one.

 

new one of what? it cant help any body else in the future if you don't give a clear solution

 

To those who I have confused with how my problem was fixed I replaced the catalytic converter.