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Old 10-03-2011, 09:52 PM   #1
luka
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Default EJ20G TPS Error Code 31

the following conditions have been/were met. I didn't have to make any adjustment to satisfy these three conditions.

No. 1 & No. 2 are conducting when throttle is completely closed
No. 1 & No. 2 are conducting when throttle is 0.7mm open
No. 1 & No. 2 are not conducting when throttle is 0.9mm open

With the car on the ON position and TPS connected to the ECU I have the following

brown wire (closest to firewall) 0 closed, 4.39V WOT
Black wire - 0V constant
Red wire - 5.1V constant
White wire 4.8V closed, 0.98V WOT

I did adjust the throttle cable a few months ago because I noticed when in WOT the throttle plate wasn't fully open. ie the top stopper wasn't hitting the throttle body so I adjusted the cable just enough that they would touch at WOT.

I'm guessing my adjustment has now made everything out of whack since I didn't also adjust the TPS, but the three conditions have been met accordingly as per this shop manual I have so I'm kinda confused :S

I would appreciate any help.

Thanks!
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Old 10-04-2011, 11:43 PM   #2
luka
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someone must have had a 31 error code before... or at least have a link to a test procedure? or another way to adjust besides the closed/0.7mm/0.9mm method?

thanks,
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Old 10-05-2011, 01:12 PM   #3
Xenonic
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It may sound like a dumb suggestion but have you reset your ecu? You didn't mention if you had or not. Other than that I don't think I'm gunna be much help here, just thought I'd point that out :P
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Old 10-05-2011, 08:52 PM   #4
luka
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yeah I reset it, reset the codes a few times and it keeps coming back.

I read more online and apparently there are two types of TPS's, inverted and noninverted... but for mine I'm getting both signals, a + voltage at WOT and a 0 voltage at WOT.
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Old 10-07-2011, 03:33 AM   #5
pmugabi
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Adjust the TPS so that you have 4.5V at the white wire with the throttle closed. IIRC TPS voltage should be between 4.3 and 4.7 when the throttle is closed.
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Old 04-11-2012, 04:19 AM   #6
bl_easy
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luka, did you ever find an answer to this? I am now researching how I am going to tackle the same issue on my 93 EJ20g.

I'm wondering if messing with the throttle cable and the idle screw could be the reason for the issue, too. Seeing as there was no CEL before I R&R'd every last bit of the car.
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Old 05-27-2013, 03:52 AM   #7
kimokalihi
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I have the same code 31 for my TPS. 91 legacy SS running EJ20G and EJ20G ECU robtuned. All diagnostics turn up within spec using the FSM procedures and I even replaced the TPS with a brand new $300 OEM subaru TPS. So Frustrating.
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Old 05-27-2013, 04:39 AM   #8
kimokalihi
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My 91 legacy FSM says voltage should be 4.4-4.8v fully closed, 0.7-1.6v fully open. I keep reading that impreza TPS voltages are the opposite. 0.7-1.6v fully closed, 4.4-4.8v fully open. Is this true? That would explain my TPS code and why it goes away when I give it gas and comes right back on when I let off all the way. I may need the JDM TPS.
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Old 05-27-2013, 05:37 PM   #9
eg33GC
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you HAVE to have the jdm tps. It is 5 closed 0 open.

I have a few for sale if needed.
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Old 05-28-2013, 12:16 AM   #10
kimokalihi
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I do need one. Sent you a pm. My swap is a 97 forester ej20g but the tps was not compatible being too new, for my 91 legacy harness so I had to reuse the ej22t tps and a different ej20g wrx ecu that rob tuned and sold me. Nobody ever told me this tps is any different than the jdm impreza tps.
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Old 05-28-2013, 01:44 AM   #11
pmugabi
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You can also swap the ground and power wires around if you don't want to swap TPS. I'm using the Ver3 TPS (which is opposite to the Ver1 and 2 TPS) and just swapped those wires around to get it reading as the ECU expected.
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Old 05-28-2013, 02:51 AM   #12
kimokalihi
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I read that but josh (legacy777) told me it wouldn't work. Its working for you and you've measured the voltage to confirm it?
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Old 05-28-2013, 01:56 PM   #13
pmugabi
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Yes, works perfectly. The ECU reads the voltage correctly and there is no CEL. It's a 2 minute job to swap the connector 'pins' in the socket and does not need any wire cutting. Use a small pick to lift the tab holding in the terminal and then pull it out and swap them over.
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Old 05-28-2013, 04:02 PM   #14
rob
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Paul, a good point was raised about the idle switch. Doesn't switching them around reverse the idle signal as well?

Really it is a moot point as it sounds like Kimo has the proper TPS that goes from closed to open, 5v -> 0v.

-Rob


EDIT: The idle switch would not be reversed. It would be stuck at 5v and the ECU would always see it as "not idle"

Last edited by rob; 05-28-2013 at 04:41 PM.
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Old 05-28-2013, 05:12 PM   #15
kimokalihi
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Well that's not good then.
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Old 05-28-2013, 10:04 PM   #16
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Quote:
Originally Posted by rob View Post
Paul, a good point was raised about the idle switch. Doesn't switching them around reverse the idle signal as well?
Odd, I don't get the idle switch CEL. I'll check the voltages this weekend and report back to this thread.
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Old 05-29-2013, 03:15 AM   #17
rob
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Paul, which TPS are you running on which engine?
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Old 05-29-2013, 10:14 AM   #18
kimokalihi
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Marnix "Only 3-pin TPS sensor (MY97-98) has the opposite values."
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Old 05-29-2013, 01:58 PM   #19
kimokalihi
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I figured out my problem. Idle Switch was way out of adjustment. This is for the 4 wire 89-96 TPS with built in idle switch. The gap between the idle screw and throttle linkage was way too big. Adjusted it to FSM specs and the problem is gone. Throttle response is great now and no more engine stalling at light throttle. The idle switch was being engaged when cruising because it was so far out of adjustment.

More info here: http://bbs.legacycentral.org/viewtop...7409&start=125
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Old 05-30-2013, 04:35 AM   #20
pmugabi
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Quote:
Originally Posted by rob View Post
Paul, which TPS are you running on which engine?
97 TPS on 93-95 engine.
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Old 05-30-2013, 06:59 PM   #21
rob
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Quote:
Originally Posted by pmugabi View Post
97 TPS on 93-95 engine.
Well that would explain it right? The 97 TPS is a 3-pin sensor that does not have a built in idle switch. Switching the wires would have no affect on the idle switch signal because it doesn't exist

But that raises a more basic question; How are you not seeing an idle switch error code? Are you not running the ej20G ecu?

-Rob
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Old 05-31-2013, 03:54 AM   #22
pmugabi
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Oops, never even realised this. The 97 diagnostics do not include code 42 for the idle switch as well.

Yes, I am running an EJ20G ECU. I think I just left the wire unconnected
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Old 03-14-2014, 01:37 PM   #23
luka
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Quote:
Originally Posted by kimokalihi View Post
I figured out my problem. Idle Switch was way out of adjustment. This is for the 4 wire 89-96 TPS with built in idle switch. The gap between the idle screw and throttle linkage was way too big. Adjusted it to FSM specs and the problem is gone. Throttle response is great now and no more engine stalling at light throttle. The idle switch was being engaged when cruising because it was so far out of adjustment.

More info here: http://bbs.legacycentral.org/viewtop...7409&start=125
Hah! Turned out this is exactly what was wrong with mine. Noticed the plate wasn't shutting all the way so played around with that screw but instead of leaving it wide open I left it touching. Once I left that little gap and cleared codes it was gone!
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