My car has a #31 engine error code HELP!

[CarlosPTR210]

Help!

My car has a #31 engine error code :1zhelp:

I already measure the resistance between terminal THA and E2 in the AFM, I measure 1,551 Ohms at 90.4F, when I switch the ignition on, I measure 1.14V.

I already swap to other AFM and the error continue.

Engine symptoms:
At idle some times the A/F is very rich and some times the engine
shouts off (A/F 10 or less)
At idle some times the RPM drop from 660 to 430
If I increase the RPM the engine RPMS and also the A/F return to
their normal readings.

So I have the problem only at idle, what can I do :aigo: ?

What resistance do you measure between THA & E2 in the AFM and at what temperature?

If you switch the ignition on, what voltage do you measure?

Thank you all.

 

[Nick M]

Unless you switched to a new meter, then your test didn't confirm anything. The best way to check is on the Hz scale. Have you cleaned the meter on the inside with any sort of spray? If so, that is a very likely cause of your A/F problem.

 

[CarlosPTR210]

c’mon guys, :1zhelp:

Take the measure of the temp resistor of your AFM!, then I can use it like a reference.:1zhelp:

I don't want to buy a new AFM, and continue with the #31engine error code.:cry:

Why! my car was so happy few days ago:cry:

 

[supramike7m]

check the wires on the plug closely. i couldnt hardley tell that mine were barley holding till i really had a look at them.

 

[jetjock]

Carlos my man, you're barking up the wrong tree here. The THA sensor isn't critical and the voltage you're seeing won't trigger a code. You need to measure the other more important part of the AFM.

With KOEO measure between VC and E1. Then with the engine idling measure the voltage between KS and E1. It'd be better if you could measure frequency but voltage will do. Do this with the AFM plugged in. Report what you find.

 

[shaeff]

31 Air Flow Meter Signal
Diagnosis
(7M-GE) Open circuit in VC signal or short circuit between VS and E2 when idle contacts are closed.
(7M-GTE) Open or short circuit in air flow meter signal.
Trouble Area
Air flow meter circuit
Air flow meter
ECU

how to test the AFM:

http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?Section=FI&Page=96

-shaeff

 

[CarlosPTR210]

Carlos my man, you're barking up the wrong tree here. The THA sensor isn't critical and the voltage you're seeing won't trigger a code. You need to measure the other more important part of the AFM.

With KOEO measure between VC and E1. Then with the engine idling measure the voltage between KS and E1. It'd be better if you could measure frequency but voltage will do. Do this with the AFM plugged in. Report what you find.

OK! thanks, let me check today, today, and will post at night the result.

 

[CarlosPTR210]

Carlos my man, you're barking up the wrong tree here. The THA sensor isn't critical and the voltage you're seeing won't trigger a code. You need to measure the other more important part of the AFM.

With KOEO measure between VC and E1. Then with the engine idling measure the voltage between KS and E1. It'd be better if you could measure frequency but voltage will do. Do this with the AFM plugged in. Report what you find.

OK! here are the results:

The engine running at idle:

E1 - KS = 127 - 167 mV
E2 - THA = 1.04V

Note: Today morning and during the test, the engine don’t has the idle problem,
Why? I don’t know.

 

[jetjock]

127-167 mv across E1 and KS? I bet the car doesn't rev well. Assuming you measured correctly either that AFM or the connector has a problem. What is the voltage between VC and E1? I'm gonna guess it's 5 volts because THA is valid.