Misfire and boggs down when cold, 98 4runner v6

[Seanz0rz]

Ok so, yesterday I started up the truck to go do some errands. Truck started fine, but felt a little shaky. Pulled out of the drive way and drove to the stop sign. when pulling from the stop sign, the engine boggs down and the truck shakes, almost feeling as if it is going to stall. Truck feels shaky when accelerating, but smooths when coasting. once the truck warms up, the symptoms are gone.

same thing happened today. but today it finally flashed the CEL, but it went off after some number of flashes.

some other details:
i am missing one of the coil pack bolts, which i will replace later today and try again.
plugs and wires are ~ 5 years old
my latest smog report shows i am very high in HC

code reader is on its way and should be here tuesday.

to me, it feels like a fuel fault, like its getting too much fuel, flooding, and nearly stalling. this would also explain the high HC in my smog test.

not sure why this corrects itself when its warm.

so avy and i are pretty sure its fuel related. does anyone else have any other ideas? things to test? etc?

[Seanz0rz]

coil pack bolt is replaced. started the truck and it did not do it again, but it did the same yesterday, bad in the morning, later in the day it was perfectly fine.

im hesitant to start a dismantle until i get the code read.

oil has a fuel smell to it, so i think leaky injector.

[4x4mike]

Interesting. I'm not sure the lack of a coil bolt would have any effect. How is your gas? I had a friend have similar stalling issues and turns out he had water in his gas.
It's been raining a lot here and I've noticed black trash bags held down with traffic cones on the lids of the fuel tanks at gas stations. Doesn't give me the warm and fuzzys. I don't need gas and will wait until it drys up if I can.

[Seanz0rz]

I'm at the bottom of a tank. ill go get some tomorrow. still doesn't feel like that is it because its fine when warm.

[slosurfer]

Ignition Coil?

[Seanz0rz]

im going to go drive it to the gas station and see what it does. either ill get the same thing and be able to describe it better, or my bolt fixed the problem (unlikely)

[Seanz0rz]

ok sit-rep:

started the truck, started as usual, ran fine for 30 seconds.
shifted into reverse, ran fine for 20-30 seconds.
shakes started as i was backing out of the driveway, so i didnt see what the tach was doing.
bogged down at first stop sign, but not as bad as before. when it stopped, the engine surged, but that may be because i had my foot harder on the gas this time.
bogged down a little bit at second stop.
not at third, and after that it ran fine.

got a full tank of clean, high quality gas.

once the symptoms stopped, the truck ran fantastic from idle, low rpm load climbing a little hill, WOT, etc. its great as long as it is warm.


still cant do much until my tool gets here, so today ill do an oil change and diff fluids, etc. brakes, and maybe rotate the tires.

[slosurfer]

Did you pull the codes? Could have a code stored in there even though the light isn't on

[Seanz0rz]

yeah code reader come from amazon tomorrow morning. last time i used an autozone code reader it reset the code before i saw what it was... (probably user error but i dont trust them)

by 12pm tomorrow i should have a really good idea of what is wrong with it.

[slosurfer]

Cool! I forgot yours needed a code reader. Hopefully it helps and gives you an idea of what's going on

[Seanz0rz]

got my code reader, plugged it in, no codes whatsoever.

this is really frustrating...

this morning when i started it up, i had no problem with it at all. didnt bogg, stumble, buck, surge, anything. started up great, ran great.

i'm confused. any insight?

[paddlenbike]

I would start with the simple stuff. Clean the MAF (there's a temp sensor in there that can get dirty and throw off the calculations for the air/fuel ratio), clean up the spark plugs, clean the throttle body and if you haven't touched it, perhaps clean the idle air controller.

[Seanz0rz]

IAC and TB are clean. I will clean the MAF later today and check it and the TPS with the specs in the FSM.

[Seanz0rz]

no issues this morning either. im beginning to think maybe bad gas. ill keep monitoring it, but as far as im concerned, the truck is solid again.

[4x4mike]

Did you guys have rain around the last time you filled up? Like I mentioned above you had similar problems to a friend of mine and thought I'd throw it out there. In his case in as in a 250 shifter kart but after a race, especially if you win like he does, they test the gas to make sure they're not doping. Through that test and another he found he had wet fuel. FWIW he uses 110 octane from a sealed can.

[Seanz0rz]

i honestly cant remember if it had rained when i filled up last. i remember filling up in the rain, but not sure if that was this tank or the tank before (i fill up so often between all the vehicles, i cant remember)

it was raining the first two times it happened, and it had rained the day before it happened the third time (which wasnt as bad)

could my ECU or wiring be getting wet somehow?

[YotaFun]

I had that issue and found one of my spark plug wires wasn't connected correctly at the coil pack

[Seanz0rz]

tried again this morning (over 48 hours since it was last started, and cooler than the previous mornings)

did it a little bit, but only when under load (trans in drive or reverse, but NOT in park or neutral)

no codes, and it corrected itself quickly once the engine started getting some warmth to it

[MTL_4runner]

Pull off your coil packs and try looking for water/rust traces or carbon arcing on the boots.

[Seanz0rz]

so an update.

on thursday, 3-29, i started the truck and drove it around the block. i got it to misfire, and flash the check engine light. read the code. P0306, cyl 6 misfire.

truck ran great for the entire trip, did well on fuel (but not too well, indicating leaning out of the AFR) and no problems EXCEPT FOR:

driving through a deep water crossing, water splashed up into the engine and caused a P0300, P0304, P0306. that is random misfire, and cyl 4 and 6 misfire.

not sure if that has anything to do with my problem, but maybe moisture is getting on the wires and causing arcing back to the block instead of through the plugs.


my intended course of action:
get a spray bottle with water. start the truck and spray the wires and look for arcing back to the block under moist conditions.

[YotaFun]

Sean, I had that happen to me, I found out one of the wires wasn't plugged in fully into the coil pack and cause an arc.