Troubleshooting P0135 and high short term fuel trim (+30ish at idle)
- Thread starter jcormier
- Start date
OP
Checked intake and exhaust for leaks via smoke testing. Found a leak in the muffler; so that's another future project, but intake and exhaust looked fine around the actual engine.
OP
Nope, vacuum gauge looked fine. Going to check the rocker arms and pushrods next.
OP
Injectors are all new, didn't do a leak-down as compression test was bang-on at 135-145 psi across all 6 cylinders.
OP
Update: Still idling rich, rockers looked fine, nothing wrong with the valves. Going to soak cylinders 1-3 in seafoam, give it an oil change, and see what happens.
OP
Yep. I got a replacement when I did a radiator flush a few years ago, never installed it.
OP
Well, I finally found out what the problem was... Here's a photo of the intake valve on cylinder 1 on the near side of the intake port. Looks like some blowby on that valve. Probably only happens sometimes and at low RPM. Looks like I'll be taking the heads off this weekend....
OP
Update: Thanks everyone for your help; running like a dream now. Turns out the valve in that cylinder was just gunked up and didn't need a full rebuild, just some serious cleaning. Root cause was the coil pack.