Cylinder Misfire still after replacing spark plugs, coils, and wire set

I have a 2002 tundra with the v6. It has 170k miles. I got a code for cylinder 2 misfire and replaced all the spark plugs, ignition coils and wire set. It didn't seem to help. I deleted the code and it ran good with no issue for 200 miles before it threw the code again and some other codes like random misfire and i think cylinder 1 misfire.

The person I purchased the truck from was the original owner and said they only ran 93 octane in it since it was new. I just purchased it and run 87. I tried the seafoam in the gas tank and that didn't help either.

I just purchased this truck and am not familiar with these engines. For those that have seen this issue before, what is the most likely cause now after doing what i've done so far? I'm assuming it must be the fuel injectors. What do you guys think? Should I go ahead and just replace all the fuel injectors? If I replace those and the issue still persists then I really don't know what else it could be at that point.

Thanks

 

Shot in the dark. Timing on bank 2? Has the timing belt been done?

 

Not that I know of. Was going to do that until this happened.

 

I'm no expert, but short of a blown head gasket this will probably be your last best guess... So, I woukd wait for someone more experienced here..

 

Are you hearing/feeling/noticing anything weird or just the codes?

What brand coils and plugs did you buy and where did you buy them?

 

Have you checked compression?

 

I used ngk spark plugs and import direct for the other parts. Bought from O'Reilly's.

You can definitely tell the car is misfiring. It will vibrate and shake the car at a stop or slow speeds.

 

Don't sell yourself short, verifying timing is a great place to start if OP hasn't checked. This is also a good time to check the belt itself and make sure it's in good shape.

I don't know as much about the V6 engines because I don't own one. I tend to only deep-dive on stuff I own, it's easy to apply the knowledge when it's sitting in front of you.

 

I would check the fuel pressure before replacing costly injectors. You could probably send the injectors out to be cleaned and tested for a couple hundred bucks and they could tell you if any are defective (cracks, bad flow) after being cleaned. So how long have you driven the truck before you made all these changes? Was it running fine initially? Since you say "still", I'm guessing this has been going on for a while.

 

Are the v6s as picky about denso coils as the v8s?

@omgcorey have you swapped coils from one side to the other to see if the code follows?

 

This ^^

And let's be real: Fuel injectors rarely fail. That's literally the second to last thing I'd be replacing, with the first-last-thing I'd replace being the fuel filter. It's never the fuel filter.

If it's a misfire condition, I'd be first confirming 100% on timing. Does anyone else remember this fiasco? He thought timing was cool, but it wasn't and dozens of pages over months of work ensued. Exactly why next step should be confirming timing and checking that belt while in there.

We rarely see misfires are caused by something electronic, unless a coil pack has failed or a ground is loose/bad. And rarely does one coil pack fail fail, much less two or more at the same time. A misfire on more than one specific cylinder combined with a random misfire code speaks to another issue that would cause misfire conditions. Timing. Lack of fuel pressure. Intake or vacuum leak. It could potentially be ECU fail, but ... that's low on the list IMHO.

Assuming people are using OEM Toyota/Denso coils - since that's important in this case, using OEM, others have had problems even with quality brands like MSD coils - and the coils were sourced from a reputable location, i.e. not scAmazon, fleaBay, WallyWurld, then I'm less inclined to think they're the problem.

We have had other folks on here with bizarre misfire/no-start conditions. Sometimes because the ECU took on water. Other times, it only affected seemingly-unrelated cylinders which actually turned out to have a pattern with one specific branch of wiring harness (i.e. 1-4-6-7 or 2-3-5-8 which, if memory is working, are wired in groups, somehow, I forget.

 

How do I go about checking the timing?

 

Process is probably in the FSM which is available for download in the 'So you bought a 1st Gen' thread in the sticky thread section. There may be an easier way without taking off all the stuff he has off here, but this German mechanic dude makes great Toyota videos.

https://www.youtube.com/watch?v=WvObnquZeNQ​

 

This will tell you more about getting in there, same engine although not the same model:

https://www.youtube.com/watch?v=JIM8y9z0PXQ​

 

Do you have the 3.4 or the 4.0? I had a random misfire in my old T-100 with the 3.4 that only showed up when the engine was warm. Ended up being a bad fuel injector.

 

3.4

 

It ended up being the fuel injector. Replaced and it and it runs great now.

 

Thank you for posting what it was. I’m having similar issues on my V8, but I’m thinking it’s the Toyota OEM counterfeit coils from eBay.