1997 FZJ80 Occasional Rough Idle, Occasional Misfire, Loosing My Mind

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bakerbrian

bakerbrian

10 Year
Joined
Feb 7, 2014
Threads
12
Messages
102
Location
Franklin, TN
Hey!

I have a 1997 FZJ80 and I am having the following issues:

It will run perfectly for about three months then all of a sudden it will idle rough, smoke, smell really rich then throw a misfire code on cylinder 5. It will then clear up and run perfect for another three months. Today with extremely cold weather (9 degrees) I went out to warm it up. Started fine but smelled really rich and didn't have much power until I drove it about a mile. It cleared up but throws a check engine light which is the misfire code on cylinder 5.

Here is what I have done so far:

New charcoal canister
New OEM plugs
New OEM plug wires
New OEM cap
New OEM rotor
New Exhaust
New OEM O2 sensors

Also, no pressure when opening the gas cap ever. I have check the injectors wires and they look perfect.

I am just at a total loss on what is going on. Any help would be greatly appreciated.

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Get an automotive stethoscope, take a mental note on how each injector sounds when it’s running perfect ( should make a very noticeable injector noise through the stethoscope ) then when it’s misfiring check all of the injectors again if number 5 sounds weak I assume your injectors sticking open or closed / intermittent. Just had a 95 Tercel coupe come through my shop that was one part of my diagnosis. Along with compression and checking other boxes like spark and injector signal. It’s a little rudimentary but it works. But a injector is what I was thinking at first so I started with the stethoscope cause the misfire was on cyl 3 and the companion cylinder wasn’t misfiring so I knew it wasn’t the coil ( wasted spark setup coil on plug with a companion wire similar to how it is on a 3.4 )
 
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Agree with above and look at the connector and wiring as well
 
MissahPapaJ said:
Get an automotive stethoscope, take a mental note on how each injector sounds when it’s running perfect ( should make a very noticeable injector noise through the stethoscope ) then when it’s misfiring check all of the injectors again if number 5 sounds weak I assume your injectors sticking open or closed / intermittent. Just had a 95 Tercel coupe come through my shop that was one part of my diagnosis. Along with compression and checking other boxes like spark and injector signal. It’s a little rudimentary but it works. But a injector is what I was thinking at first so I started with the stethoscope cause the misfire was on cyl 3 and the companion cylinder wasn’t misfiring so I knew it wasn’t the coil ( wasted spark setup coil on plug with a companion wire similar to how it is on a 3.4 )
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Thank you so much! I wish you were closer, I would just bring it to you.
 
defintly check for un metered air getting in past the MAF, Crank Postition sensor can cause weirdness issues when it starts to act up, as can the Coolant temp sensor
 
I had that happen to me that's the reason I mentioned it.
And yes it was months in between at times.
I once had a cracked air intake and lately a cracked MAF housing (possibly due to too much torque on it).
 
bakerbrian said:
Thank you so much! I wish you were closer, I would just bring it to you.
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Every one should get an automotive stethoscope if they wrench on anything half way. Some times it’s nice to listen to different parts of the engine so you have an idea what normal is. It’s it primitive, yeeeesssss. But also cheap and effective tool to own. Think I’ve had mine for 15 years or so and I use it frequently…. But also I’ve been a open shop tech for 20 years, jack of all master of none.

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Check injector, injector plug (cracked, corrosion), injector wire, wiring harness at EGR (burn or abrasion of insulation), and main harness behind lower glove box support ( back edge of support has an edge that can abrade harness cover and individual wires).
Hope your spark plug wires are genuine Toyota. Denso wires gave me intermittent misfires (not extended episodes).
 
MissahPapaJ said:
Get an automotive stethoscope, take a mental note on how each injector sounds when it’s running perfect ( should make a very noticeable injector noise through the stethoscope ) then when it’s misfiring check all of the injectors again if number 5 sounds weak I assume your injectors sticking open or closed / intermittent. Just had a 95 Tercel coupe come through my shop that was one part of my diagnosis. Along with compression and checking other boxes like spark and injector signal. It’s a little rudimentary but it works. But a injector is what I was thinking at first so I started with the stethoscope cause the misfire was on cyl 3 and the companion cylinder wasn’t misfiring so I knew it wasn’t the coil ( wasted spark setup coil on plug with a companion wire similar to how it is on a 3.4 )
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Thank you so much for the information. Once the snow and ice has passed I am going to give this a shot.
 
LXDOC said:
Check injector, injector plug (cracked, corrosion), injector wire, wiring harness at EGR (burn or abrasion of insulation), and main harness behind lower glove box support ( back edge of support has an edge that can abrade harness cover and individual wires).
Hope your spark plug wires are genuine Toyota. Denso wires gave me intermittent misfires (not extended episodes).
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I will check all of these. Thank you for the guidance.
 
Injector harness. I had similar sporadic issues. New injector harness and the problem disappeared. That was 10 years ago....no, 12....well, a while.
 
bakerbrian said:
Did you go back with original harness or one of the eBay ones?
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bakerbrian said:
Thank you so much for the information. Once the snow and ice has passed I am going to give this a shot.
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When snows on the horizon, there’s no better time to get the rig ready for summer shenanigans! Get your ass in that garage yeeewwwwwww!!!! Get a heater if need be.
 
I had almost the identical symptoms in my LX. @LXDOC's suggestion is exactly what solved my problem. After all of the ignition, compression and fuel checks I was completely bumfuzzled. It was an intermittent short of one injector from the wiring harness to/from the ECU. It frayed over the years being in contact with a sharp penetration in the firewall. I taped up the offending wire individually then wrapped a plastic armor around the whole wire harness, taped it good and three or four bolts later it was fixed.
 
MissahPapaJ said:
Get an automotive stethoscope, take a mental note on how each injector sounds when it’s running perfect ( should make a very noticeable injector noise through the stethoscope ) then when it’s misfiring check all of the injectors again if number 5 sounds weak I assume your injectors sticking open or closed / intermittent. Just had a 95 Tercel coupe come through my shop that was one part of my diagnosis. Along with compression and checking other boxes like spark and injector signal. It’s a little rudimentary but it works. But a injector is what I was thinking at first so I started with the stethoscope cause the misfire was on cyl 3 and the companion cylinder wasn’t misfiring so I knew it wasn’t the coil ( wasted spark setup coil on plug with a companion wire similar to how it is on a 3.4 )
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this is sage advice.

Swapping out the ECU harness (that also controls the injectors) will be an expensive way to set everything back to ground zero. This might fix the issue but if the injector itself is clogged or faulty, then the issue will persist.
 
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