Shepper

I tried asking this on another forum and didn't recieve any replies, so I'll try it over here too.

Can anyone tell me what the voltage output from the 7 pin should be on the AFS with respect to the RPMs that the engine is running?

For instance, I found an old post where a guy talks about taking measuremnts at certain RPMs:

"I did my measurements at idle, 2k rpm, 2300rpm, 2500rpm, 2700rpm, 3krpm, and 3200rpm."

But, he doesn't say what the voltage output was.

The reason I'm asking is because I'm still having problems figuring out a way to correctly calibrate the AFS in my car since the PO messed with it. I had a person drive the car the other day who had driven it before I installed this different engine and he said that there was a noticeable lack of power.

I have checked compression and it was good. I know the AFS is not adjusted correctly and by measuring the output at certain RPMs seems to be the only way to calibrate it most accurately.

I'd take any numbers into consideration whether it's the actual specs, or just the specs that someone got from running a quick test and recording the voltage at various RPMs.

7thStranger

I don't know if this helps but the Haynes states:

Voltage and resistance checks for AFS

Voltage between terminal 9 and ground 8 or more volts.

Voltage between terminal 3 and ground 5 volts.

Voltage between terminal 7 and ground with door closed 250 to 260 millivolts. sensor door open 4.60 volts.

Mark Lue

Shepper, I donn't think many of us would measure and record the results you desire. It's just less hastle to just purchase a used AFM from a bone yard or off Ebay. I donn't know how accurate the voltages would be, for different air temperature, engine loads and RPMs.

There are only 2 ways to adjust the AFM, by reindexing the spring on the barn door or by turning the screw under the plug on the body of the AFM. My screw was adjusted by the PO but I was able to get an approximate setting because the PO screwed the screw IN, which left a visible shadow all I had to do was screw OUT the screw until it matched the shadow about 7 1/2 to 8 turns from the bottom. It works as I've passed the smog test 2 times since. Just remember screw IN = Richer, screw OUT = Leaner. Benchmark the position of the screw by screwing it in all the way and counting the number of turns, so you can put it back later if you so desire. Once that is done play around and see if your adjustments make a difference.

Lack of power eh, check for vacumn leaks? How is your O2 sensor? Clogged CAT?

I haven't had to reindex the spring for the barn door so I'll leave that to someone else to explain.

Danno

Well, there's no way to accurately quantify the voltage of the AFM except with the car off. Fully closed, it should read about 0.25v and fully open (by hand) should be around 4.60v.

Since it measures air-flow, you can't say that at XYZ-RPM, it should read this or that because each car will be a little different at the same RPM. The only easily measured value is at idle which should be 0.79-0.85v and 840-950rpm.

Paul Bloomberg

Does the 85.5+ DEE send 5 volts to the AFM like the turbo? The Haynes manual says 8+ volts for the non-turbo and 5 volts for the turbo. It doesn't say anything about the difference from early/late.
Paul

awilson40

Heres a site showing how to bench test the AFM
<a href="http://frwilk.com/944dme/" target="_blank">http://frwilk.com/944dme/</a>

I read somewhere about setting the AFM spring with the O2 sensor. Disconnect the O2 sensor, have the car fully warm and read the voltage at 2000 RPM. IF the O2 voltage is above .5 v, then you are rich...tighten the spring. Once this is set. Measure the voltage at Idle. Adjust the mix screw for the same reading.
My car reads .8 v at 2000rpm and Idle
...slightly rich.