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post #1 of 2 Old 03-08-2010, 08:16 PM Thread Starter
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obd1 code 31

I have a 1989 Toyota 4runner I just bought. It sat for about a year to a year and a half an dwas not started. I put a battery in it and 5 gal of gas and it started fairly easy. It is missing at an idle and really doesnt like you to accelerate. It has a check engine code of 31. It might be just my imagination but smells like rotton eggs or sulfer. I was thinking that the catalytic converter would be bad but I was wondering what would cause the engine code of 31. It is a 2.4 liter 4cyl 5 speed 4x4. Thanks
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post #2 of 2 Old 03-08-2010, 09:51 PM
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Code 31=Air flow meter, to see full codes see below also measure the voltages and reistances on ECU and compare with service manual to isolate problem.

About half of the ECU codes stored on the first & second generation EFI Toyotas don't show a constant blinking check engine light therefore you must pull the ECU codes to see if a fault is registered.

To pull the ECU codes:

All 1980-1995 and including 1995 EFI equipped vehicle allow you to find engine and related faults by pulling the ECU (computer) codes without the need for a handheld OBDII diagnosis scanner, the sites listed below have the fault codes needed to pull the codes and the instructions on how to do it:

http://www.efisakh.narod.ru/at_toyota.htm (auto tranny codes)

Pulling the ECU (EFI computer) codes is the first thing I do to diagnosis a problem thereafter I reset the ECU to see if the same problems show up and if so I then take voltage measurements at each ECU wire both with the engine running and not and compare with the factory service manual, I also close the ignition switch after a cold engine and also after a warm engine and compare the resistance values with the factory service manual. This technique will completely isolate your problem without having to do trial and error and it is the technique I use when repairing tv's, vcr's, home/car audio.

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1995 Toyota 4-Runner,22R-E with 243 000 KM
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