My misfire thread..

[clx16]

WOW. @Rifleman yeah i remember either thinking it was NLA or too expensive when i needed to replace mine. It is a pretty critical piece too, but I figured I could get an aftermarket one and run that and keep a the leaky one as a trail spare if it stopped working. 4 years almost and still seems to work fine. its hard to swallow 820 bucks for one...

 

[Killdozer1776]

I'll definitely be going with the $150 dollar amazon/advanced/oreillys option as others have said it worked fine for them. Worst case, I can return it for a refund.

I'm not in a hurry on that though unless some of the experts here confirm that it could be the cause of some of our misfire issues..

 

[BILT4ME]

A couple years later now. I was searching the archives of this forum and came across my own thread. See that 3 people are viewing it. Funny (not) how common this problem is with these trucks. 50 people will say 70 things fixed their problem, but it's intermittent (random misfire) so it's hard to be certain. And sometimes what seems like a fix really is just temporary coincidence.

Anyway I have done a lot of maintenance during this time but still have the misfire issue. It had gotten pretty bad recently.

Pulled the cap off the distributor as I hadn't checked that since I replaced it. Oil from inside the cap poured onto my hand as soon as I pulled it off. So the shaft seal is shot.

I imagine oil in the distributor could cause misfires? But the contacts in the cap seemed dry except for the center one. It hasn't been ran in a couple weeks so that's to be expected. The oil inside would cause issues besides the leak itself, right? I'm not sure if the oil just pools at the bottom or gets "sprayed" all over the contacts and eventually drips off of them. If this is the case, I'll get a new distributor.

Wiped it all out and it ran better. I hope I'm getting close.

Also, get your PCV valve and grommet refreshed, maybe you valve cover seal and spark plug tube seals, as well as vacuum lines.

Without a proper vacuum being pulled on the crank case, your distributor internal o-ring could see pressure and it will push oil out to the distributor cap because it is open to atmosphere. If all your seals and hoses are tight, you won't get a leak of oil into the distributor.

 

[Killdozer1776]

Also, get your PCV valve and grommet refreshed, maybe you valve cover seal and spark plug tube seals, as well as vacuum lines.

Without a proper vacuum being pulled on the crank case, your distributor internal o-ring could see pressure and it will push oil out to the distributor cap because it is open to atmosphere. If all your seals and hoses are tight, you won't get a leak of oil into the distributor.

I have done all of those within the past several months. Brand new all of it.

 

[SNLC]

There is a trouble shooting process for this outlined in the FSM.

Start with the crank position sensor, test it and move to the next item. You can test the dizzy, plug wires, coil and finally the igniter. I have seen cheap china parts in the ignition cause misfires. On my truck it was a cheap aftermarket igniter. You should also check the wiring harness at the igniter. The coil also grounds via is mounting bracket, all the LHS engine bay grounds besides the starter ground at this location too. In fact there are five grounds in the engine bay on this side and one on the other side. Head RHS back to firewall, LHD head at engine slinger, at coil on shock tower, just below main fuse panel on LHS inner fender, battery and LHS inner fender at batter tray. I have seen plenty of these unhooked by mechanics and never hooked back up again.

Until you have done the trouble shooting process on the ignition system and double checked all the grounds I wouldn’t be checking anything else.

Toyota wiring connections have an o-ring where needed to keep the water out. I have seen these fall out and also just not be there. A lot of years and potentially a lot of people have put their hands on the engine bay.

Cheers

 

[Killdozer1776]

There is a trouble shooting process for this outlined in the FSM.

Start with the crank position sensor, test it and move to the next item. You can test the dizzy, plug wires, coil and finally the igniter. I have seen cheap china parts in the ignition cause misfires. On my truck it was a cheap aftermarket igniter. You should also check the wiring harness at the igniter. The coil also grounds via is mounting bracket, all the LHS engine bay grounds besides the starter ground at this location too. In fact there are five grounds in the engine bay on this side and one on the other side. Head RHS back to firewall, LHD head at engine slinger, at coil on shock tower, just below main fuse panel on LHS inner fender, battery and LHS inner fender at batter tray. I have seen plenty of these unhooked by mechanics and never hooked back up again.

Until you have done the trouble shooting process on the ignition system and double checked all the grounds I wouldn’t be checking anything else.

Toyota wiring connections have an o-ring where needed to keep the water out. I have seen these fall out and also just not be there. A lot of years and potentially a lot of people have put their hands on the engine bay.

Cheers

I've checked all the grounds and cleaned them all again in the past week just to make sure. I will go through the process in the manual from step one and report back.

 

[Killdozer1776]

Update if it helps anybody else out with theirs

It's 100% the harness.

Last time it was running bad it was worse than ever and had 3 dead cylinders. Wiggled the harness near the EGR while running like many times before, but this time it changed.. it leveled right out and right now with no rain/snow it's still running great.

Not sure if repairing the harness is worthwhile. My fear is that the dead spots are dispersed and hard to pinpoint (perhaps replace/extend every wire from before/after the EGR?) but a new harness is significant in both the cost and labor

 

[bubfuji]

The engine harness is still available from WITS' END, and Toyota. At one point, $600.00 - 700.00. While invasive to install, the difficultly is minimum. Decisions....

 

[wlittleman]

I just finish reading your thread killdozer. I've been dealing with this problem for 7 years. I have intermittent engine stumbling issues that seem to happen when it's raining or simply humid. Nowadays, if I am up in the mountain and fire her up in the morning, i need to warm the engine up (perhaps to evaporate all the conversation) before I can drive.

I've done much of what others have described on this thread... making sure the engine can maintain vacuum, applying dielectric grease to connections, replacing plugs, distributor cap, plug wires, pcv valve and grommet, engine temperature sensor, and several other things I've long forgotten. My wiring harness is also damaged and there is exposed wire adjacent to the EGR. I wrapped the harness on silicon tape, which i suspect barely passes as a shade tree mechanic hack.

The fzj80 still stubbles in the most epic way until i let it idle long enough for whatever moisture to evaporate. Maybe one of these days, I can find someone who can splice or insulate the exposed wire(s) properly.

 

[alia176]

Even though I don't have any discernible ill effects from the aging harness, I know things can be way better. I'm going to hoard a new harness until the time I yank the engine to do a second HG, along with a refresh. It's gonna be much easier to install this harness on an engine stand vs leaned over for hours.

 

[OOCustoms]

Bump- reviving this thread once more- I have the same stumbling/surging idle with no power- only for the first 1-2 minutes, only when it's full cold start. After inital stumbling/low idle it behaves fine, it won't do it again until it cools down for quite a while. Did you guys ever get it sorted out?