3FE code 51, sudden loss of power (1 Viewer)

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I have a 3FE in my FJ40, but figured that there is a lot more 3FE knowledge here.

I have had the motor running for about6 months, all has been great. Idle was low, but otherwise it ran great. Tons of power, smooth running, etc. On a 700 mile trip last weekend, the low idle was causing problems with it not staying running in the single digit temps, so we adjusted it, and ended up a bit too fast, but didn't change it since it was our last day and I figured I"d correct it when we got home.


No problems all day, cruiser ran fantastic. Coming through Reno I was doing 75 easy keeping up with traffic. Did 60 over Donner summit. Faster then my 80 can honestly. However, about 20 miles from home, it started getting a miss, and stumbling. Major power loss, a hill that normally I go up without much speed loss, I couldn't keep it over 45... and it sounded ragged. I pulled over at the top of the hill and checked things out, didn't see anything disconnected. I pulled each plug wire one at a time, and each one affected it, so it didn't seem like a spark issue. It was too hot to mess with injector plugs, but I did check them when I got home and nothing was loose or damaged. I drove it home. No CEL.

The next day I checked wires and plugs to things, injector plugs, ect. I jumped the diagnostic port, and did get a code, code 51. That seems like it can be any number of things, so.... where do I start digging into this problem. Partly I suspect maybe an issue with the throttle position sensor, since we did mess with the idle a day before, but we just ran the little screw in a few turns... and it ran fine for most of two days before it had an issue.

Any ideas what I can check to start narrowing down the issue?
 

Spook50

My daughter likes Stitch
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Something sudden like that (and this is without having the book with me for reference on the code) during a drive would make me suspect something electrical failed. Possibly the igniter or the coil failing. Is your coil an OEM or aftermarket? I would test that first.
 
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I e felt with 51- it’s not that mysterious. What system
Does the code call out? Do you have the 3fe manual? It has TS flow chart for each code. I wanna say it’s TPS, but honestly can’t recall. I know that I chased some issues on mine for a while, and after going thru all the tests for most of the electrical, it seems to be bulletproof. Gotta think some of that is simply breaking up corrosion on contacts as the plugs were undone and redone. Also, make sure all your grounds are good
 
Joined
Mar 10, 2006
Messages
1,337
Location
Grass Valley, CA
I e felt with 51- it’s not that mysterious. What system
Does the code call out? Do you have the 3fe manual? It has TS flow chart for each code. I wanna say it’s TPS, but honestly can’t recall. I know that I chased some issues on mine for a while, and after going thru all the tests for most of the electrical, it seems to be bulletproof. Gotta think some of that is simply breaking up corrosion on contacts as the plugs were undone and redone. Also, make sure all your grounds are good

I have it downloaded, I need to go to Staples and just print myself a binder. From what I read, the TPS is a major cause of the code 51.






I havent' have time to check it much still, but it seems like it's blubbering.. running rich. Smells stinky, just has that blubbering sound.

I will try to check the TPS tonight. I need to just make some time. I have two other 3FEs so I can swap some parts around too if needed.

Thanks.
 
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Might just need to calibrate it. I did and it gave me trouble again a few thousand miles later. So I took off the th, cleaned it and the intake plenum along with the icsv; replaced gaskets cleaned tps and reset it again and that was solid. Definitely go thru the fsm steps. Saves a s***on of time.
 

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