Thanks Ron, that is great info. I did test the VAFM earlier this evening. The E2 - Vs test, where you watch the resistance increase increase as you open the flap -- The resistance would gradually increase as it should; however, when it was fully open, it dropped back down to the starting position.

 

That doesn't sound right, and will certainly confuse the ECU at high air flows. I think I would go ahead and open it up and have a look inside. Just keep things clean around it when you do. If you find something to fix, you can seal it back up with duct tape temporarily to try it out, and RTV it again once you've got it working properly.

 

Finally, problems solved. A new (used) air flow meter fixed both air codes. The knock sensor wasn't hooked up; the wire had been pulled out of the plug. I fixed these things and hoped the oxygen sensor code would also go away as a result. However, it did not.

I got a new oxygen sensor and installed it, but that did not fix the code either. Then I noticed that at some point, the wiring had sat on the exhaust and melted. It was in bad shape. I removed the bad section of wire and then the code went away.

I took the truck for a little drive and it ran great. I think we are in good shape now, finally! Thank you everyone for your input. This has been quite the adventure.

 

Great! Glad you got everything taken care of - that's a real feeling of accomplishment! And, thanks for letting us know how it all came out.

 

I just went through some afm issues after I bought my 86. I found the afm top had been removed previously. I removed the cover and watched the needle move while running. I found the door was getting stuck causing it to run lean. I lubed up the door and it runs like a champ. hope this helps.

 

Where did you get your replacement afm? I am having some of the same problems but I'm running super rich about 6 miles to the gallon or less my afm had been opened prior to me buying it not sure what they adjusted probably richened the condition but when I try to lean it out it will die. I have a new denso o2 sensor in the mail so I'm looking at remanufactured afms as well.

 

I got it from: http://www.pattersonaw.com/

They're local to me, but maybe they would ship to you. I also did some checking on eBay and found a couple at decent prices. Is your engine light on?

 

No but I've tested it according to factory specs it fails in all the temperature readings so it's not giving the right ratio and It triggered my o2 sensor. I got a new tps as well because I was throwing a code for it before and I'm still throwing code 4 for a temp switch on top of the thermostat housing replaced it and new splice as well. Still getting a code for it tho?.

 

When you installed the TPS, did you set it up with an ohm meter, to get it in the necessary position?

Also, I had tested my air flow meter with an ohm meter. It checked out fine, in terms of resistance. However, it was still faulty. My mechanic said that the ohm meter test doesn't tell the full story, when it comes to the air flow meter. There is more going on than just the resistance. Sounds like yours isn't even within specs though, so that can't be good.

For the code for - did you try pulling the EFI fuse for a minute, to erase the engine codes, and then see if it comes back?

 

The best way to test the VAFM is to open the passenger kick panel, find the terminal (pin 2 on the 1994 3vze) on the ECU that senses the VAFM, and connect a DVM to it. Then turn on the ignition and move the vane. You should see the voltage go smoothly from 0 to 5 volts as the vane moves through its range. If there are any hiccups or sudden jumps, the VAFM is defective. If you get no signal (stuck at 0V, stuck at 5V, or just randomly drifting) the wiring is likely defective. You may also want to wiggle the connections at the VAFM and/or the ECU to see if anything looks intermittent.

You can test the TPS the same way. It's connected to pin 1 of the ECU.

The ECT can be tested similarly. It is sensed on pin 4. It has a voltage to temperature relationship that roughly follows the table below. Temperatures are in degF. Sorry about the crummy table formatting - does anyone know how to make this interface do lined up columns?

Sorry, I think my first table was reversed. I think it should be
Voltage, Temperature
0, 266
0.5, 176
1, 133.997
1.5, 104
2, 83.9984
2.5, 64.4
3, 46.4
3.5, 27.9968
4, 7.998801
4.5, -11.9992
5, -31.9972

Doing it this way tests the VAFM/TPS/ECT exactly the way the ECU sees it, through all of the relevant wiring.

 

Great idea RJR

 

I'm on the hunt for a 0.85mm feeler gauge because Its off a little I didn't have the right size I'll check the ecu I've erassed my codes many times. I only drive real close to home so I don't really notice much because it barely has time to heat up

 

Hi punks. Do you have any feeler gauge? Perhaps you can add a few of the petals together to arrive at 0.85?

 

The closest I can get to is .84 or .83 I'd have to check again