Code 31 Help

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Stiles87

88' na->t
Feb 23, 2006
10
0
0
Tacoma Washington
Driving on the freeway the other day and my check engine light came on and the car lost all its power. I was able to limp it home as long as it didn't build any boost. I checked for codes and got Code 31. I tested my afm its fine. I checked all of the wires coming from the afm to the ecu and they are all fine too. Wondering if anyone has run into a problem like this before and what they did to fix it.

Also, could a boost leak cause a code 31? thats what I thought it was until i pulled the code.
 
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Stiles87

88' na->t
Feb 23, 2006
10
0
0
Tacoma Washington
S

Stiles87

88' na->t
Feb 23, 2006
10
0
0
Tacoma Washington
So I borrowed a known working afm from my friends car and it still had the same issue. Car will start up, idle and even rev fine. As soon as it starts to build any boost pressure the check engine light will come on and its looses all its power. I checked all of the wires for resistance and they all seem to be fine, no grounds or extra resistance. I checked the wiring diagram and looks like there is a connection with the throttle position sensor. Could my tps adjustment cause a code 31?
 
3p141592654

3p141592654

90T
Oct 11, 2005
3,816
16
38
Thousand Oaks, CA
No chance. Its the AFM or wiring. Most likely an open or short circuit in in the Ks signal line. If you've got a DVM with frequency readout then probe Ks and see if you have a signal (20-40 Hz at idle). Also check for 5V on VC to E2.
 
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solardrgn

New Member
Feb 6, 2008
77
0
0
socal
not trying to thread jack but ive had the same issue for several weeks. i tested the wiring from the AFM plug to the ecu plug. and these were my readings
in ohms
KS - 2022
E2, THA, VC, E1 - all .3

where should i start...
 
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Stiles87

88' na->t
Feb 23, 2006
10
0
0
Tacoma Washington
3p141592654;1748673 said:
No chance. Its the AFM or wiring. Most likely an open or short circuit in in the Ks signal line. If you've got a DVM with frequency readout then probe Ks and see if you have a signal (20-40 Hz at idle). Also check for 5V on VC to E2.
Click to expand...

Probe it on the ecu side or right at the afm?
 
S

Stiles87

88' na->t
Feb 23, 2006
10
0
0
Tacoma Washington
solardrgn;1748806 said:
not trying to thread jack but ive had the same issue for several weeks. i tested the wiring from the AFM plug to the ecu plug. and these were my readings
in ohms
KS - 2022
E2, THA, VC, E1 - all .3

where should i start...
Click to expand...

Not sure if you have figured out what is going on with your car yet, but I got mine fixed. Turned out the that O2 sensor wire had slipped under the heat shield and partially melted. Had nothing to do with the AFM, AFM wiring or ecu which is why it took my so long to figure out what was going on.
 
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