Persistent misfire in cylinder 4 of the 5vz-fe

Best of luck I'll let you know what I find after I work on mine though it'll be a bit!

 

So Red_03Taco I got around to doing the spark plug test and these are my results:

Cylinder #4

Cylinder #2

Cylinder #6


Please do note that the test light was constantly flickering, I think my phones shutter speed lined up with the test light blink intervals and gave it an on/off pattern, you can kinda see this effect change tempo a bit when my phone adjusts its focus on cylinder #6's video. The test light was constantly flickering though, you'll just have to trust me. Gives me more peace of mind that this is probably fuel injector related since I got the same results across the whole driver side.

On fuel injector note for the rest of ya'll I'll be doing the fuel injectors this weekend and the valve cover gasket as well so I'll take pics and do a write up when I go back to work on Wednesday next week. I opted to go the cheaper route and get the injector rehab injectors, the Denso 23250-0A010 to be exact, so I guess I'll be the first vocal test dummy on here to say if they cause a worse misfire or if they keep me going for a another 1/4 million miles.

 

Nice videos and yea at this point I think by process of elimination you've more or less diagnosed it as injectors.

Are those injector rehab Denso injectors supposed to be the same or comparable to the upgraded Denso injectors that Motor West is selling (the ones that Lexus used in the RX300)?

 

So got down and did the valve cover gasket and the injectors this past weekend. Tearing it down wasn't too bad, lots of air inlet items. I think the worst part was all the cleaning. It was very obvious at some point this truck sat for a few years and collected a lot of grime and the lower part of the valve covers were especially weepy to the point I spent two evenings last week using engine degreaser to try and uncover the old gasket and the actual metal of the heads and covers.



Here are my henchmen being voluntold to clean the half-moons and the valve covers



The actual interior of the valve train was sludged the fuck up lol I went through with a plastic razor blade, a few picks, and two rolls of shop towels and got 20 years of marlboro tar out of the machine.



Also, I'm curious if ya'll know what these holes in the upper corners are in the head. They look like oil channels almost, but driver side rear corner (pictured above) was the only corner not drowning in black tar heroin so also thinking they could just be collection holes for debris. Anyways I cleaned them off from their gooey demise



An example of one of the many mud dobber wasp nests hiding under the fuel rails, the plenum, and any other little cranny that shows this thing sat for a period of time. All cleaned out by my hand though. Every crisp wasp larva corpse vacuumed up, to be forgotten.. Besides the insane amount of cleaning me and the other maids did, the valve covers went very smooth. I always forget how much I hate scrapping gasket mating surfaces for a clean seal though.



Now we move onto the injectors; the old ones looked super burnt out when I pulled them out, and upon visual inspection the new injectors looked near identical.



The injector seats were FILTHY with dust and crud, so we had to double team the cleaning efforts to make sure no dirt fell into our pristine little hole.



BUT for all the precautions we took to be careful with the engine openings, those were thrown out of our practice the moment we started opening up the new injectors, where my friend IMMEDIATELY dropped the injector for cylinder 2, followed immediately by me snapping cylinder 1's new injector rim. We concluded that it wouldn't mess up its function, so we sent it. Normally in the videos I saw that people put the injectors into the rail then put the rail into the injector seats, but we did it opposite and had to turn the new injectors as we mated the fuel rail to the new O -rings.



My normal torque wrench is out of spec, so I have my digital-clanker temp placeholder, and we had to jig it up to feel remotely good about torquing down the fuel line bolts. Screen said 25ft-lb and there's no fuel leaks there so we're good.



I had my girlfriend double check my torque on my valve cover bolts (she is not a gear head at all) and put the tip of the rachet handle on the bolt and was asking why it wasn't fitting. quite a lol moment for us. All the bolts were torqued down, and I was ready to start putting her back together!



So, I stopped taking pictures at this point, but when we had it all back together, we turned her on and noticed cylinder 3's injector was dumping fuel from its connection with the fuel rail. I thought all hope was lost when my friend and I realized I had two extra fuel line crush washers and some injector O-rings I had ordered. We got to work really quick, taking the throttle body off and accessing the fuel rail; when we pulled the injector, we saw the O-ring was mangled to shit so we popped the replacement O-ring on and saw it was WAAY to big. So, I was like why not use the old OEM Aisin injector O-rings. We pulled the O-ring off the 24-year-old injector, and it was snug as a bug in a rug on the new injector. Selected the two least mangled crush washers we just put on and used those and the two extras I had and torqued everything down! Turned it on and it drives so smooth!

The misfire was gone, and everything is as it should. Or at least it was. I took it on a 60-mile drive two days after and I noticed when I'm at idle there's still a slight tremor; it feels like the misfire but a lot smaller and it's making me think the misfire is slowly coming back. Here's a video where you can see the tremor shaking my water bottle and the stick shift. I might be tripping, and it could just be engine noise so I'm thinking of doing the motor mounts and transmission mounts to see if that helps.



The other thing that I'm concerned about is when the misfire was present, the engine would SHAKE like it was going to die around 3k RPM, it's a lot better now that the misfire is presumed fixed, but when I'm in 5th and going like 75mph and the engine is between 2750-3000rpm I get a ton of vibration in my body and cab along with my shifter. My suspension is shiet and Bilstein 5100's are the next big purchase for this thing so maybe it could be the suspension at that speed buuut idk otherwise I wouldn't be here asking.

 

Thanks I'm glad to have ruled out a spark problem
but yeah nail on the head with those injectors

 

I also think it has the original fuel filter on it and I have a new one at home so I'm going to throw it on tonight and see if that helps

 

Great job, so far!

 

Were the valve clearances checked?

 

Negative and I will neglect my shims till I'm forced to do them, at which point I will buy a different 5vz-fe with 61,000 miles on it and do them on that engine

 

Fuel Filter swapped but not real change that I can feel

 

Shit. Be nice to maybe try another ecu. I don’t have a clue.