2005 4.7L multi cylinder misfire

I have searched the forum and seen others with similar issues but I couldn't find where a solution was posted so forgive me if I bring the subject up again.

About a week ago I developed a multi-cylinder misfire after heavy acceleration when passing another car.
My Tundra has 181989 miles with new NGK plugs and Denso coil packs at 172k so I don't suspect that the issue is there

About 3 months ago I ended up with very old gas in the tank resulting in a tank drain but only after about 10-20 miles of driving.

Once this misfire started I checked the vacuum lines, replaced anything remotely old, when that didn't help, and considering the previous fuel issue, I went ahead and replaced all of the injectors- unfortunately, that didn't help either.

Any assistance would be greatly appreciated

 

All grounds are good?
Any word on fuel pressure?
What about MAF?

My first inkling is always going electric on misfire codes, but given what you've replaced, if you know wiring is solid, I'm thinking about anything related to [global] fuel delivery and air delivery/monitoring.

Others may have different ideas.

 

I have not tested the fuel pressure, I just started to research how to check the fuel pressure. I haven't looked at the MAF, but I will put it on the list

 

I think there's an FSM of the '05 somewhere here on the forum, in someone's Google Drive. If you can find it, and you have a digital multimeter, it'll give details on how to test MAF, possibly other stuff.

 

So what CEL codes does it have set?

 

Sorry new to message boards..FSM?

 

Factory service manual

 

P300, P301,P302,P305,P306,P307,P308,P2241

 

I’d say P2241 has something to do with the misfires.

 

Agreed,I don't think it threw that code earlier, but I may have just scrolled over it

 

An bad O2 sensor will throw all kinds of codes.

 

I will replace them all to get ahead of any other potential issues. I am not reading where this could cause a misfire, but nothing else seems to make sense

 

I think the gist is maybe tying back to fuel/air ratio again, but on the back side of combustion. ECU adjusting fuel/air ratio based on what O2 sensors are seeing coming off the backside causing possible combustion issue, if they're getting bad data, fuel/air ratio could be wrong, causing misfires. But I may be wrong here.

I've already had to replace one of my factory O2 and I've only got ~72k miles. They don't last forever. If you've never replaced yours, they tend to fizzle out over time but don't show drastic, obvious signs. Go OEM on them, but don't buy off scAmazon or Fleabay, you're liable to get counterfeits.

Is that the actual issue? Can't say. I usually attribute misfires to electrical, like I said before, but it's not always the cause.

 

Factory service manual link

https://drive.google.com/file/d/0B-...WjA/view?resourcekey=0-lv7xW9_5TKqpbWKbBzVP0Q

 

Intake leak? A la bmf?

 

I had some crazy misfire, codes, possible fuel issues a while back. Really intermittent and the symptoms led me to believe (incorrectly) that it was a fuel issue. Turns out the wire (driver side front of timing cover) to the oil pressure switch and crank position sensor had gotten into the drive belt and damaged it just enough that it only caused intermittent problems. Buried just enough I didn't see it until I started removing cover to check cam sensors. Mostly hard starts and couple stalls with a side of a few random codes.

So check wiring real good. Good luck!

 

Find the trouble O2 sensor and try to unplug it and plug it back in, could be a bad connection. Buuuttt most likely it gone teets-up.

 

Does it run with the misfire?

 

Interested in finding out the cause.

 

Mine was a bad idle misfire. I think his is gonna be fuel related.

 

Thank you

 

I just picked up the O2 sensor and will install it tomorrow, see what happens

 

I looked at every hose I could find, replaced the secondary air pump and check valves just to get ahead of any potential issues there.

 

I will give it a look. The mystery to me was how it came on while under load out of nowhere . Thank you

 

It runs, but miserably.

 

Starting to wonder if the fuel pump has something to do with it so I will be testing pressure at rail

 

Fuel pump is a logical thing to check. Certainly could be causing your problems. Has to be ruled out at least.

 

You did that before replacing the O2 sensors

 

the fuel pump only primes when engine is turning over, so pressure is checked while cranking. Then you do a leak down type test to see how long it holds pressure.

Mine showed as potential fuel issues. Even failed the leak down test. So I changed pump and fuel pressure regulator. Neither fixed my problem. Not to discourage, just don't get too focused on one solution without ruling out others first (like I did).

 

A friend brought over a compression gauge today, #6 cylinder is dead, yes, I know, should have done it first, but with the other issues, I just didn't think this was the problem. We scoped it and saw where the piston met the valve. No puncture, but a decent impact. Not sure the direction I want to go next.