Mysterious misfire

[OffRoadScott]

So I got my LC back from the dealer. They checked it all out and said everything they checked was in spec, everything being plugs, wires, etc. They "SAID" they test drove it too and could not feel the miss but once I was down the block I felt it right away.

My question to you could this be a fuel injector issue? If so would it be worth my time replacing ALL the injectors at the same time and be done with that?

Is there anything else it could be? It is not throwing any codes either.

 

[inkpot]

Could be a lot of things. Is it a constant miss or a random pattern? Constant at least narrows it down to one consistent item, such as 1 loose injector harness clip. OBD II rig should show a 03xx code for any misfire.

 

[Tedward]

Maybe think of something that's not fun to check for and ask the dealer to do that. They owe ya for giving you back your truck that is still obviously missing. If the techs dont have much experience with a 94 wagon they probably didnt like working on it and dont want to mess with it. Ask for a free bit of diagnosis because someone didnt even mention the miss, ya know.
If not, I wouldn't start by replacing injectors. If only because they are expensive. At least get a cheap auto stethoscope and listed to each one to see if its clicking. Just taking the injector wire harness plugs off usually means 1,2 or more of the clips break. Sucks.

Start over at the beginning like it was never at the dealer and make sure the plugs cap rotor are all as should be. Get a cheap stethoscope and listen before you take out injectors is my opinion.

Try to test the injector plugs for power if you remove them. And maybe check compression in the cylinders too to see if a valve is. ot seating. You know, all the stuff a mechanic would do. Not all dealer shop workers are mechanically inclined. Not sure about by you but in my neck o the woods none of them have I've talked to have EVER worked on an older lc

 

[LINUS]

Have you given the engine wire harness a solid “evil eye” yet?

Esp since motor mounts are getting old & floppy, wire harnesses are going to start to suffer from that.

If the injectors themselves have been out & cleaned, then going after the harness & grounds, fusible links, etc - would be my next look.

Have you got dielectric grease in all the sockets yet?
-That or lithium grease will combat any corrosion or moisture related issues, but you do live in AZ.......so your “norm” or issues you commonly see take down a motor are far different than myself.

But the grease don’t hurt nothing, and you see the motor for different POV’s than just standing over it checking the fluids & such.
‘Grain of salt’ -advice I suppose.

 

[OffRoadScott]

Have you given the engine wire harness a solid “evil eye” yet?

Esp since motor mounts are getting old & floppy, wire harnesses are going to start to suffer from that.

If the injectors themselves have been out & cleaned, then going after the harness & grounds, fusible links, etc - would be my next look.

Have you got dielectric grease in all the sockets yet?
-That or lithium grease will combat any corrosion or moisture related issues, but you do live in AZ.......so your “norm” or issues you commonly see take down a motor are far different than myself.

But the grease don’t hurt nothing, and you see the motor for different POV’s than just standing over it checking the fluids & such.
‘Grain of salt’ -advice I suppose.

From what I can tell the wiring harness is good to go but there could be that one gremlin.

This thing during idle is like a V8 with a large cam.

Yes I do live in AZ. I have applied the dielectric grease in the past.

 

[richardlillard1]

So is it an actual miss or just a lazy stumble at idle? The former is indicative or a problem, the latter falls into the category of noise, vibration and, harshness and probably means absolutely nothing.

I’ve driven and ridden in a lot of FZJ80s and they all have a lazy stumble to some degree. Even the ones touted as running like a sewing machine.

 

[OffRoadScott]

So is it an actual miss or just a lazy stumble at idle? The former is indicative of a problem, the latter falls into the category of noise, vibration and, harshness and probably means absolutely nothing.

I’ve driven and ridden in a lot of FZJ80s and they all have a lazy stumble to some degree. Even the ones touted as running like a sewing machine.

I would believe it is a miss. On the highway, it misses/stumbles enough to shake the steering wheel and cause a loss of power up till 2200-2300. At idle it feels like it is the same cylinder every time it does its thing.

 

[PDoyle]

Sounds like an electrical issue . For the hack of it check the wiring harness behind the glovebox where it meets the body. How old are the cap and rotor?

 

[OffRoadScott]

Sounds like an electrical issue. For the hack of it check the wiring harness behind the glovebox where it meets the body. How old are the cap and rotor?

The cap and rotor have less than 10K miles on them. I will check the harness where it enters the cab next on Wednesday the next time I am off.