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Symptoms and code...do they match enough to warrant swapping TPS


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My 83 wagon with EJ22 swap does this:

 

Code 31 in memory, and is the only code.

 

When you drive the car it idles BEAUTIFULLY. When you put a load on it while driving it will lurch, want to die and occasionally stall if you aren't careful. It doesnt seem to want to be pushed hard in acceleration either, it will rev to like 3250 or so and then past that it runs weird as well, almost acting like it isn't getting fuel.

I have yet to be able to rev it under load to 5000 RPM....And I would like to! LOL. I do have the really rare throttle body with the adjustment screw on it...for idle I think so I think it probably idles well because that screw overrides the TPS?

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screw?

 

Check your knock sensor. That can cause a driveability issue without throwing a code. Also you can bench test the TPS with an analog meter. You can use digital, but analog is nicer to see the sweep. You may have a dead spot in the tps.

 

Now i know you say your throwing a code. But you say its an 83 with a 2.2L . Is there a typo someplace i'm not seeing? (like a 93?)

 

nipper

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Hopefully Subaru upgraded the FSM in the EJ series, the TPS values and figures in the FSM for the XT6 are not even close. i would assume the FSM for the EJ series isn't the same, but just a word of caution.

 

i would inspect the knock sensor and wiring as well like nipper suggested.

regarding the TPS if it's consistent in it's issues, which it seems it is, then the wiring is likely okay. i'd check for corrossion on the TPS sensor connectors, the metal tabs that actually plug into the wiring harness. and i'd check the wiring harness side as well for corrossion.

 

you could also check the pins for the TPS at the ECU, with all the wiring work that was done a bent pin wouldn't be that surprising. i'd expect more problems than you're having, but it's an easy check at least.

 

the TPS on the older series engines can be disassembled and cleaned internally and can help substantially in the running department. never looked at the EJ stuff, but i'd imagine it can be disassembled as well. but you're probaby like me and have a bunch you can just swap out.

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Not sure if you have, but here's the scans from the FSM regarding the TPS. The last scan tells how to adjust the TPS....and is based upon the idle switch.

http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/TPS_testing1.jpg

http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/TPS_testing2.jpg

http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/TPS_testing3.jpg

 

Personally, I'd say with the symptoms you have, and the stored code....I'd replace the TPS. You can just replace the TPS, and not have to replace the throttle body, just adjust the TPS per the instructions in the last scan.

 

Regarding the bypass screw.....that thing can cause you lots of hell. Unless you have a way to monitor the duty % on the IAC valve, I'd almost recommend just screwing it down all the way and let the IAC valve do what it's supposed to. I went through hell trying to fix a high idle that was caused by cleaning the TB and having that screw (unknown to me at the time) bypassing too much air.

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Replaced bad TPS and adjusted the used TPS I put on in its place. Adjusted out really nicely but still not helping unfortunately. CEL is not on and hasn't come on yet. I tested its functionality though by unplugging the TPS while the car runs and immediately the engine light comes on.

The car falls flat on its face for some reason and I can't figure it out. Tonight I tried replacing all the gas with fresh and that didn't help for more than a few minutes.

 

Screw that screw in ALL the way??

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Shawn you say

almost acting like it isn't getting fuel.

 

It takes more gas when moving than just sitting and

winding up the RPM.

 

Would you please describe the fuel system you have.

 

Factory EA81T pump? Filter? Regulator, Pump control system.

 

Might want to plumb a fuel pressure gauge in to the

fuel rail pumbing, maybe just after the fuel filter.

 

Note: an electric oil pressure gauge will work.

I have done this for testing purposes.

 

The sender is designed to not melt down with

gasoline (think oil saturated with gas from a flooding carb

or other such problem).

A brass "T" plus two hose barbs - and we have a bingo.

 

Hope this helps.

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Screw that screw in ALL the way??

 

Yeah....you can give it a shot, and see what happens. The newer TB's were designed without it there. Just count the number of turns so you can get it back in the same area if it doesn't help, or makes things worse.

 

Other thing to try....unplug the IAC valve electrical connector, and drive it around....see if that affects anything. You will have a pretty high idle, but the car should be driveable.

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