I have a 94 4Runner with the 3.0 still... Last month I was having issues with the afm. Would only start for a second then turn off. Jumped b+ and FP in the diagnostic plug to bypass the COR and AFM but that didn't make a difference.

I tried another afm from a friends truck. It worked for maybe a month then recently started having the same problems.

My question is... Is there something that could be causing my air flow meters to be frying or do I just have terrible luck with AFMs that are naturally dying? Is it common for the 3.0 AFM to have problems?

Any input would be greatly appreciated because I am at a standstill.

THANKS!

 

You still got stock air box and dry filter??

K&N type filters that are too heavily oiled have been known to foul VAFMs.

 

Stock air box, yeah. First time it fouled was a dry filter. The second time was a k&n I got from a friend.

 

could be an intermittent short to the fuel circuit opening relay. possibly a problem with the efi fuse or relay..... the vafm is a slightly updated version of the old bosch units from the 70's-80's on german cars, like bmw, so it's not really as good design as a maf, plus creating inlet restriction, lol.... 2 things i've seen them prone to: the contact point to the fuel pump is poited for better life, but still a contact point, you can bend one of the arms to get a new point of contact. the second thing is corrosion on the shaft, causing it to stick sometimes.... also, you can't have any cracks/splits in the intake piping, which is common to happen with the stupid wire hose clamps...
take a box cutter and cut through the silicone on the plastic top plate allong the aluminum, but don't go more than like 3/8" deep over where the wires go in. you can measure voltage with the key on and actuate the arm to see if it's passing through the contact. it will be the 2 foreward ones that touch when you spin it away from parked. measure it before doing anything, and the second tang can be bent slightly up or down to get fresh contact, not the first..... possibly the replacement unit was just already worn out a bit, and you are having bad luck in that form...

 

Why do you think it's the VAF (AFM)? The test you ran is the one to do, but it says "not the VAF".

 

When the issue was happening the first time I went through pretty much everything in the fuel delivery system. Tried a different COR, checked continuity on both banks of injectors, new efi relay, even a different ecu. Also an extra distributor I had. After taking an ohm meter to the VAFM I found that there were quite a bit of dead spots as I open the vane. So I was sure the VAFM had just died.

After getting an older VAFM from a buddy's truck I put it all back together and it started right up fine. Ran for about a month and now I'm having the same issues.

That's where I'm stumped. Don't know if I'm just having bad luck with air flow meters or there is an underlying issue I'm not seeing. Wondering if this was a common issue.

Tomorrow I will probably bite the bullet and spend the money on a re-manufactured VAFM with a warranty.

 

Thanks for your reply!

I'll check the voltage on this one when I get home from work later. Would breaks in the inlet piping cause the VAFM to fry or just not work?

Also I got a very vague response from a guy on a Facebook group when I mentioned this problem that just said "coolant sensor". Have any input on that? Hahaha

 

Bought a new remanufactured VAFM... No change.

 

have you thought about the TPS?

 

cracks will make it draw air in through the cracks and not the vafm