Just curious.. how many people out there have actually had a bad vafm. I have tested and retested and I can't find anything wrong with any of the sensors on the truck yet I get a code 31 for the vafm circuit.

 

Wiring and/or corroded connectors give trouble.

Weak grounding points make sensors wacky.

Maybe if the VAFM tests good, it is good.

 

Only when the last owner took it apart trying for more power

Poor connection from corrosion pins getting worn etc

remember the codes are for that complete circuit

 

I have a hunch that it's been taken apart before but I tested the whole circuit every wire back to the ECM and relay while trying to move them around to get a short or something and I put all new grounds on

 

I have had two bad AFMs to be bad and not throw a code. Run a resistance check per the manual and they failed.

 

i've had one corroded which caused it to stick.

 

I have another one I am going to put on and pray that cures it. I don't have any other ideas. thanks guys

 

Code 31 is "open VC or short from VC to E2". If the wire or connection is open between the VAFM (pin VC) and the ECU, the VAFM can pass its resistance tests just fine and you'll still get the code, because the problem isn't in the VAFM, it's in the wiring or the ECU itself.

Like Wyoming says, you have to check the entire circuit.

 

Like I said I tested the whole circuit everything ohmed fine.. Tested the AFM as per manual as well and it tested fine. I put the new one on today and it seems to be running fine but was too busy to drive it much so look for tomorrows feedback.

 

Remember sometimes meter probes can make good contact but there can be corrosion on plugs you just can`t see with the naked eye.

I fought with something like this for a whole day once every thing checked out good with the meter plugged together it just would not work !!

Sprayed all the plugs with electrical cleaner plugged it together and after 8 hours it worked.

Lets hope all works out for you .

 

Great news.. It's fixed!! Thanks guys!

 

Congratulations! So the fix was the new VAFM?


The FSM test for the VAFM is not comprehensive, and will not find a dead spot as the wiper arm sweeps the circular PC track inside. It only measures basic connectivity inside the VAFM. To be more thorough, you can do one of two things.
1) Disconnect the connector and measure the resistance from VS to E2 as you slowly move the vane across its range. You should see a smooth change in resistance as you move the vane. Any skips or jumps indicate a defective VAFM.
2) (best). Reconnect the VAFM. With the key on and the engine off, back probe the connector on the VS pin and watch the voltage as you move the vane. It should sweep smoothly from ~5V to 0V, again with no skips or jumps.


VAFM problems can be caused by a dirty or corroded wiper arm or PC track. Opening it up and cleaning it with electronic circuit cleaner can restore proper operation, at least for a while.

 

Haha I'm being punish for being excited.. So as far as I know yes the new part took care of the issue I was having with the sputtering and dying

However, I stirred up an issue which I assume has to do with it. Here's the scoop

I drove the truck this morning to work.. it's about 30 miles and it's about an hours drive cause it's a lot of dirt road and it ran beautifully and flawless.. as I was driving home from work it was purring like a kitten. Stop and go traffic it handled it fine no issue. As I was within 2 miles of home I noticed the engine temp was above normal. not crazy high but probably 230ish which I'm not sure that would cause a big problem then I got literally 2 blocks from home and it died while lightly accerating tried to start and it acted like it wanted to then stopped started looking around and everything looked normal the vafm was pretty waem to the touch and so was the efi relay and the efi fuse was blown.. the whole engine bay was hot though but it had gone to normal operating temp when it died. I swapped the fuse real quick it started I went 10 feet it blew the fuse again I towed it home put another fuse and went to measure amps across the fuse and it started and ran fine... can someone shine some light on the situation I'm not scared to jump into the work I just need some guidance

 

Before I replaced it I did that first test by the way and I thought it was normal cause it was within spec but it did move pretty rapidly as is jumped in numbers.

 

Update: it's still running fine I checked the O2 sensor wires, ohmed the fuel pump and wires, pulled the loom back where I think places could rub on the harness but I'm not seeing anything so far.. I ran out of daylight though so it will have to be a tomorrow project I am going to drive it to work in the morning to see if maybe the temperature is a factor.. hope I can resolve the issue soon it's really irritating im about to give up and sell it for what I feel is a easy fix I can't find