P0304 on 2020 TRD Tacoma

Through all of it it’s been a misfire on cylinder 4 only. At least thats all I've gotten the handful of times I've hooked up my basic scan tool. I guess I need to upgrade to some better diagnostic equipment to be able to test fuel trim.

 

If your cheapie scan tool can look at generic obd2 data then fuel trim(s) should be in there..

Is this a 4 cylinder? 6 cylinder? What year vehicle?

 

2020 TRD 3.5L, should have been more clear. Its just a basic “reader”. Reads and clears codes, thats it. Ive been wanting to buy something actually usable so i just snagged an affordable-ish autel.

 

Personally I'd hold off on an injector until you figure out where all the oil is going. Sounds like its consuming a lot.

You mentioned valve stem seals but how was that determined? Has anybody done a leak down test yet? Maybe a wet compression test? 165 psi is something but what about the other cylinders? If the others are all noticeably higher thats a clue something isnt right

Im curious if the oil is getting past piston rings or somewhere else.

 

Well two other local mechanics weighed in on it and both thought valve stem seals as well. Granted that was before it started smoking more on startup and consuming oil at an accelerated rate. Still just cloud of smoke on startup only after sitting, thats noticeable anyways.

When I swapped the plugs #1 was wet with oil and #5 was nearly caked over with burned oil sludge, the rest all looked normal besides being old and up for replacement.

They went way over on their last oil change and thats when it started smoking/consuming oil.

Today when I did compression it was drivers side only. I thought that 4 might be quite low and get remedied with dumping some oil in the cylinder. But when 2 and 4 were at 165 i called it quits there.

I’ve got a leakdown kit on the way and when that shows up I was planning on checking all 6. With that in mind I didn’t really see any point on running compression across the board, figured it jump straight to leak down for all cylinders instead.

I just wanted to check for HG today and figured id do compression on 4 and see if it came up busted and stuck my bore scope down there but didn't see anything alarming. Codes have only been coming up on 4 for misfire.

 

Is the misfire super intermittent? Does it ever do it in the driveway with the hood up?

Any chance you could get a vacuum gauge hooked up to the intake when the problem is happening?

 

At idle it seems “fine”. Their idle seems a bit rough, but from what they have described its only had the catastrophic feeling misfire maybe 3 or 4 times, so yeah, id say “super intermittent”. Last one was uphill under a decent load. He told me he’d been trying to replicate it but to no avail.

I dont currently have a vacuum gauge although it would probably be easy enough to get one I guess. Main problem now is when this started acting up I told them they really needed to park it until they figured out what was going on but they kept driving it every day, and a good 3-4 hour round trip probably once a week to town and back, we all live super remote so getting anywhere is almost always 1+ hrs of driving. And within a week or two of that it got noticeably worse. So now they aren't driving it.