4.7 V8 04 Tundra Misfire

Hey guys so my 04 TRd Offroad is acting up. We recently did all the oil seals at a dealership. We’ve got misfire on 2,4,6,8. Changed all the spark plugs. I’m getting codes for the low bank 02 sensors and a vacuum leak but no leak to be found. Any idea what’s causing my random misfires?

 

All on the same bank, most likely a ground issue. YMMV

 

Is your shit box rusty?

 

Are you actually misfiring, or did you just get the codes? I mean, is it running poorly?

 

Nope this is a Florida truck. Super clean chassis no rust at all. I swapped a new ignition coils and the misfire hopped but we ended up with 4 cylinders either way.

this thing is misfiring for sure. Low power and sounds like it has a cam when I know damn well it doesn’t. Vibrates a good amount just doesn’t feel right

 

I assume you replaced the cam seals? How soon after the seals were replaced did it start?

 

Truck was gone throw more than 6 months ago by the Toyota dealership. This happened out of the blue 4 days ago. Driving on the highway when it started losing power and limped it home. No damage to the engine but it is definitely misfiring

 

Every EFI engine needs measured air, properly timed spark and pressurized fuel to run cleanly without missing. If (A) you add or remove too much of any of those three, or (B) the ECU's sensors for those three requirements are working incorrectly, you'll likely have a misfire problem.

Given the fact these are all on one side of the engine, passenger side, and it's not misfires on both banks, I'd be leaning more towards (A) being your problem. i.e. I'd think you have an air leak somewhere, something not torqued down proper, gasket gave way, or similar, and you're getting too much unexpected air introduced, but maybe I'm talking out of my ass.

I'd blame the MAF reading incorrect air intake, but that would cause probs on both banks.

Likewise, you can't blame fuel necessarily, unless something is preventing fuel from hitting one entire bank, which you should be able to look for, and you'd smell gas if leaking I'd think.

I don't think it's spark, but if you wanted to check, you could swap coils and plugs from 1357 to 2468 and test, or just move one pair left to right and see if you're missing on, for example 1468 0r 2357 all of a sudden.

 

We swapped them over to no avail. Still on the left side. Someone said bad ground? What grounds would I check??

 

A couple ideas come to mind:
Compression test.
Check timing belt for any damage, check that it’s tensioned, and check cam timing.

 

Ground on that side, IIRC, goes from the rear of the block to the firewall, it's the braided steel wire you see hooked on the firewall a few inches left of center toward the passenger side, an inch or three below the cowl.

But if I recall from previous threads on this subject where people were misfiring on a seemingly weird group of cylinders, one member found the 4.7L coils were wired 1-2-4-7 and 2-3-5-8 so I'm not sure I agree with the grounding theory. But it's totally worth looking into.

Given it's all on the same side, I'd double check fuel delivery to that fuel rail is good, and expected pressure. I'd also be listening for leaks on that side.

Oh, and what's the story on that vacuum leak?

 

Well no code for the vacuum leak I think that was a stored code. My computer reads a lot of variables but I don’t know what’s normal so I have no reference. The ground looks find there’s no reason for it to have broken but it’s sure is tricky to get to. I’m trying to gather the most plausible possibilities because I’ve put in a few hours well many hours like half a day with no success. Not letting go of this truck way too nice to be ruined by a mystery misfire. I’ve been reading all over the forums looking for my solution. I don’t see any fuel leaks but I was gonna try some fuel injector cleaner although I don’t think that’s the issue. I put in a new o2 sensor and it made no difference as well

 

My misfire is bank 2 2-4-6-8

 

Yeah, I believe if this was electrical it wouldn't be on just one bank.

 

Re-read but may have missed. Where did you buy these ignition coils ?
Also, does your reader by chance read MAF(mass air flow), IAT or fuel trims, LTFT in particular ?

 

I’ve got an 05 4.7 double cab. Had those codes, replaced plugs and went away.