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The mkiv Supra Owners Club

Air Flow Meter (Curcuit) - Error Code 31


ChrisR

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The idle on my Supra is very lumpy plus the ECU reports error code 31.

 

From what i have read on the forum (search) a 1993 J-Spec doesnt have an AFM or MAF so does anyone know what else my problem could be.

 

The Diagnostic Trouble Code Chart is very specific regarding error code 31 in that the trouble area is either -:

 

  • Open or short in air flow meter curcuit
  • Air Flow Meter
  • ECU

 

Is there any chnace an error code 31 means something else on a 1993 J-Spec.

 

Regards

 

Chris

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Have you checked the connections to your MAP on the engine side of the intake? I don't know if it gives an error31 for that as it's the j-spec's version of the MAF.

 

Cheers Alex i will go and check. Have you heard of a MAP sensor failing and needing replacing.

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Just a bit more info, this problem first occurred on a gentle ride, not under any load.

 

At the time i had the silencer pipe fitted in the Apexi exhaust so could the pressure the exhaust system was under by having the pipe restricted have caused the MAP sensor failure.

 

Regards

 

Chris

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  • 2 weeks later...

Just an update on my running issue.

 

It turns out that error code 31 can relate to the MAP Sensor on early J-Specs even though the diagnostics code chart talks about Air Flow Mass Meter.

 

My problem wasnt the actual MAP sensor but the FCD which takes a feed from the MAP to the ECU. I dont have my car back yet to double check however i think the plug inside the TRL FCD had become disconnected from the curcuit board. This is a known problem on the early units.

 

Anyway the FCD has been taken off for now and the car runs fine again.

 

Thank you to Alex for suggesting the MAP may be faulty and to Matt Hardwood for telling me to check the FCD. Willson has been a big help too as he had a silimar problem, cheers Gordon :thumbs:

 

I probably should thank the SEARCH button while i am here :)

 

Regards

 

Chris

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  • 3 weeks later...
  • 11 months later...
Guest Xabin
Just an update on my running issue.

 

It turns out that error code 31 can relate to the MAP Sensor on early J-Specs even though the diagnostics code chart talks about Air Flow Mass Meter.

 

My problem wasnt the actual MAP sensor but the FCD which takes a feed from the MAP to the ECU. I dont have my car back yet to double check however i think the plug inside the TRL FCD had become disconnected from the curcuit board. This is a known problem on the early units.

 

Anyway the FCD has been taken off for now and the car runs fine again.

 

Thank you to Alex for suggesting the MAP may be faulty and to Matt Hardwood for telling me to check the FCD. Willson has been a big help too as he had a silimar problem, cheers Gordon :thumbs:

 

I probably should thank the SEARCH button while i am here :)

 

Regards

 

Chris

 

 

What kind of FCD did you use?? i have 31 error code to:(

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