Topic: 88 pickup EFI code 31

[booger36]

Hello everyone,

   My 1988 toyota pickup (4cyl) has been running a little rough these days. It wont go past 40mph and it backfires every now and then. It will idle just fine, but if I pop the hood and rev the engine via throttle body, it starts to choke up and wants to die.
  When this problem started, I installed a new fuel filter and that didn't help. So finally the other day the truck threw a code 31 (AFM). I did a lot of research and found this write up;

http://4crawler.com/4x4/CheapTricks/AFM/index.shtml#AFMtesting

and I did my AFM test using a ohm meter (first time using one) so I might need some help. I wasn't sure where to put the reading/setting at (on the ohm meter itself) x10 or x1k. So I did both hoping you guys could tell me if its messed up or not.

I followed this test (located on the link above...)

AFM Connector Pinouts:

As viewed looking at the AFM:

AFM Connector Pinouts
FC   E1   E2   VB   VC   VS   THA
Static Tests:

Table 1: 22RE (2.4L-4 cyl) - AFM Static Testing
Test   Between
Terminals   Resistance /
(ohms)   Temperature
0.*   VB - VC   ~100   n/a
1.   E2 - VS   20 - 400   n/a
2.   E2 - VC   100 - 300   n/a
3.   E2 - VB   200 - 400   n/a
4.   E2 - THA   10K - 20K
4K - 7K
2K - 3K
900-1300
400 - 700   -20°C (-4°F)
+0°C (32°F)
+20°C (68°F)
+40°C (104°F)
+60°C (140°F)
5.   E1 - FC   Infinite/open   n/a


Okay, here is my test (again, I wasn't sure what setting to put the ohm meter on (x10 or x1k) so I did both.

Terminal       Resistance              setting X10            setting x1k

0. Vb-Vc                   -100                                    75                                   185

1. E2-Vs                    20-400                              110                                  190

2. E2-Vc                    100-300                            75                                     185

3. E2-Vb                    200-400                            45                                    180

4. E2-Tha                                                            5                                      150

5. E1-Fc                   infinite/open                       no movement                    no movement



Again, I have no experience using an OHM meter, so thats why I put both of those values (two separate tests)
I'm putting my test up here because I have no clue if my AFM is good or bad. I have no idea how to read these things lol someone help please
thanks in advance

[twistedtoy92]

x 10 is multiplied by 10 and x 1k is multiplied by 1000! Looks like you have a bad AFM, replace it!

[booger36 [OP]]

x 10 is multiplied by 10 and x 1k is multiplied by 1000! Looks like you have a bad AFM, replace it!

ohhh good to know. I assumed that those values meant 10 and 1k but I wasn't sure. So just for my curiosity, how can you tell that its bad? It's not that I don't trust you, I would just like to know how you knew that by looking at my test. 

thanks

[twistedtoy92]

well just take your results and do the conversion then compare those numbers to the factory specs! If they are within range then its ok, if they are out of range then its a faulty component. What kind of meter you using?

[booger36 [OP]]

well just take your results and do the conversion then compare those numbers to the factory specs! If they are within range then its ok, if they are out of range then its a faulty component. What kind of meter you using?

This is what I was using....

[PETDOC]

FWIW My '88 4Runner with the same engine as yours blew it's AFM a couple of years ago. Toyota wanted north of $800 for a new one. I got a re-manufactured AFM with a 1 year guarantee from Advanced Auto for $125 and core exchange. That was 2-3 years ago and it has worked perfectly. 

[booger36 [OP]]

FWIW My '88 4Runner with the same engine as yours blew it's AFM a couple of years ago. Toyota wanted north of $800 for a new one. I got a re-manufactured AFM with a 1 year guarantee from Advanced Auto for $125 and core exchange. That was 2-3 years ago and it has worked perfectly.

I went to my local autoparts store and they too wanted $800 for a AFM. I decided to check the pick and pull near my house and luckily they had one. My only problem was that the AFM was from a 22ret turbo model. So I ran to a Toyota dealer and asked if there was a difference from non turbo to turbo afm and the guy said no. Having said that, I went back to the pick and pull ans picked one up for $18.22. Works perfect and haven't had any problems.

[twistedtoy92]

Glad to hear you got it fixed!