rough idle after some mud fun

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So we've had our FJ62 a little over a year and my son has been dying to get it on some mud. He finally got an opportunity and certainly put it in some soup. OK, no biggie, I was a teenager once too...
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After initial cleaning there was some noise up front so I had him clean up the pulleys and idlers and lubricate, which helped quiet that down.
It's idling rough now though. visibly shaking more than before. I notice that the vent hose on top of the distributer was off so figured it got some junk in there, but we removed it and it looks OK. We cleaned it up a bit but no change.
Where should I look next?
 

Godwin

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You should pull off the distributor cap and make sure it’s all clean and dry under there.

This especially since you had a disconnected distributor vent hose. Also there is an o-ring that seals between the body of the distributor and cap. If that is missing or degraded could allow water to enter the distributor.
 
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Things looked ok to my uneducated eye inside the distributer cap. Disconnecting the one O2 sensor with the wires up over the transmission was so difficult we ended up removing that exhaust pipe between the manifold and the catalytic converter. At that point we decided to go ahead and replace both O2 sensors since they are about $42 each. Will see if that sorts out the problem. One of them for sure had mud in the sensor holes that are intended to measure the surrounding atmosphere (at least that is how I understand it) so maybe that was the issue?
-Sammy
 
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Things looked ok to my uneducated eye inside the distributer cap. Disconnecting the one O2 sensor with the wires up over the transmission was so difficult we ended up removing that exhaust pipe between the manifold and the catalytic converter. At that point we decided to go ahead and replace both O2 sensors since they are about $42 each. Will see if that sorts out the problem. One of them for sure had mud in the sensor holes that are intended to measure the surrounding atmosphere (at least that is how I understand it) so maybe that was the issue?
-Sammy
Replaced both O2 sensors. Idle improved significantly. It's hard to know if it is the same as before, now I am focusing on it more than before.

Now we have a new and interesting symptom - it will briefly (fraction of a second) lose power as you gently accelerate. It occurs at about 1500 rpm. Drops of for a fraction of a second and then comes back. If we hover around that RPM it will do it repeatedly. I don't think it is the transmission since it happens even if the transmission is in 2 or L. Maybe I should start a new thread for this issue?

-Sammy
 
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Does the power blip happen if you hold the rpm at 1500 rpm when in park or neutral? basically is it an rpm issue or an rpm/load issue.
 

ceylonfj40nut

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Diagnose your throttle position sensor to see if it is working as it should. Diagnostic test is in the FSM.
 
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So in case anyone wondered how this went - we spent a little time driving it right around 1500 RPM and the "blip" would happen repeatedly. We looked for loose connections and cleaned up a few random wire plugs and generally stared into the engine bay a lot. Things got worse. Idle went down to below 500, black smoke and droplets were coming out of the tailpipe. We removed the throttle body, cleaned it, and checked with shims as per the 3FE repair manual. it was a tiny bit out so we adjusted slightly. re-assembled and idle was about the same (we didn't run it more than a few minutes). At that point I threw in the towel and took it to a shop. Was following it in my truck and it seemed to improve (judging by the reduction of smoke out of tailpipe) on the way to the shop. Anyway, the shop said that the found a couple hoses around the intake that seemed a little loose and they tightened them, but said it seemed to be OK.
picked it up ant it does seem to be back to "nominal". Little bit of white smoke at startup but otherwise pretty good.
So, I am a little skeptical, but they only charged me $89 for diagnostics so I guess I should be happy.
Do the EFI/ECU systems take a little time to "learn" like more modern cars? Is it possible that I just didn't give it long enough after we cleaned the TB and adjusted the TPS? It didn't seem like we did enough to make that big of a difference.
 

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