drkblu4runner

i have had this prob for awhile now i have spent hours looking for the prob

here is a list of what i have done:
new:tps plugs, wires,cap,rotor,

testes according to manual"
o2 sen, tps, coil, vafm, distributor pickups, egr pair, not arching from what i cat tell or and vac leaks. all cyls comp is about 150psi


the Misfire symptoms:
after it worms it is when it starts. at idl you can hear the random miss and under load at low rpm(under 3g) after 3g it seems to stop.

"
i brought it to the dealer and they said it "may" have a burnt #5 valve. that is bs they wanted 600 more just to do a leak down and that is obviously not the prob

drkblu4runner

ok so i tested the distributor and got:
G1-G=160.3
G2-G=159.3
NE-G= .198




and it runs extremely smooth with 1,3,5 spk wires unplugged


could the NE-G pickup be bad or is this norm

toyminator2000

You didn't say what engine but I had an 87 4Runner that had a similar issue. It turned out to be broken and corroded wires inside the harness that go to the fuel injectors.

drkblu4runner

its a 93 3vze does anyone know if the .198 is norm?

drkblu4runner

its weird how it seems to only be bank one

drkblu4runner

new distributor, still miss fire please help

drkblu4runner

also cant adj the tps the ohm never match up to what the serv manual says. but it was misfiring before that so idk. im about to just sell the thing im so frustrated. please any help would be appreciated.

theMonch

I had something similar with my 88 3VZE. It would feel like a miss or a stumble upon starting but then rather quickly the motor would adjust and smooth out. It would then show up as a sort of random stumble or misfire at medium engine load at highway speed. I could make it go away by downshifting to a lower gear (manual trans) and bringing the engine to a higher load. It was so intermitant that 3 local dealerships and a VERY reputable local Toy specialist couldn't diagnose. I left it with one dealership for a week so their best tech could take it and drive it home for a week. I tried plugs, wires, new distributor, new coil, new fuel filter, monitored fuel pressure under load, compression test, TPS check and adjustment, VAFM test and check, EFI engine temp sensor, cold start injector, vacuum leak tests, EGR valve and numerous others that I have forgotten.

It lasted for over a year and was getting to the point that I was considering decomissioning the old girl and getting a 3rd gen. It was never bad enough that I would not get to where I was going, but annoying enough to recognize that it was a problem.

Then I decided to replace the VAFM since I was able to procure one from eBay rather cheaply. Even though it tested out according to the FSM, I believe that the IAT sensor (Intake air temperature) that is integrated into the unit was faulty. This would explain why the problem was so intermittant. It would randomly send incorrect data to the ECM that would cause bad fuel trimming and adjustments.

Once I replaced it with the used replacement, voila...problem solved. The 3.slow actual woke up a bit afterwards and started pulling like it hadn't in years. Regained fuel efficiency as well.

Not suggesting this is definetly it, but if you have access to a buddys VAFM that you can swap in, or are willing to out for the replacement, that could be it.

Good luck and let us know if you get it and what it was.

drkblu4runner

thanks monch that may just be it i have a friend with a 90 3vze i think i can swap

drkblu4runner

ended up being the ignitor. and thanks to toy dealer for trying to tell me its a burnt valve