Hey

I have a S4 t2 with a AFM that doesn't ground it's self...so here is how it goes

AFM in car wont start/idale

AFM out and ground the the pin form the connector, Car starts idales, but dies if revved

Now is there a way to fix my AFM?
Is there a good replacement with out going standalone? ie would a s5 AFM work?
Is there a way to go with a MAF instend?

Any help would be great
Thanks

 

the S5 afm works. you just have to redo some wireing. there is a writeup on the forum somewheres.

 

What pin/wire color are you grounding? There are two ground wires in the pic below where one is highlighted in Green and the other in Blue. Which one do you believe you are grounding.

 

so you remember what the tread was titled?

 

as for the color i'll get back to you on that

 

well it's the last wire on the connector, it brown..

 

With the AFM in the car and hooked up as well as possible hunt down the Circuit Opening relay which is located under the dash just to the right of the steering column (yellow in color). There you will see a Brown wire along with some other wires including a solid Black wire. Jumper these two wires (solid Black to Brown) and start the car up and see if it behaves differently than before.

 

ok cool thanks i'll try that and get back to you..though it might be tomorrow..cuz that car is at a friends garage.

 

Are you familiar with what this Brown wire does. It supplies the Circuit Opening relay with a ground so the fuel pump will stay on while the engine is running above 500 rpm. Below 500 rpm the AFM is not used to start the car but it is used to run the car above it. The flapper on the AFM opening results in a ground signal being sent through the Brown wire. If the flapper isn't flapping then the Brown wire will not keep the car running after it is started so make sure the flapper is opening up properly. As a test you could take an LED light and place the positive wire of the light to the B/W wire in the Circuit Opening relay located on the top row middle wire of the relay and the negative wire of the light put to the Brown wire in the relay and if the AFM flapper is opened enough the light ought to light up because the B/W will have voltage and the Brown wire "should" have a ground if the AFM is working properly This is to be done w/key to on.

 

Thanks for the info. I see two wires on that circiut opening relay. Do I jump both the black wires ( 2 go into on pin/terminal)

 

Is this the original poster? If so that is "not" what was stated. Read again as it mentions a solid Black and a Brown wire and no mention of two Black wires in the Circuit Opening relay. Also, not sure what was said in bold type.

 

Ok just jumped them and nothing diff. Fuel pump doesn't prime when you first turn the key to on. It only come on in the run position.
When I ground the brown wire at the afm fuel pump primes and stays on and car startsm
If I give it throttle it dies.

What would be the next step short of a new afm?

 

Satch..both Jaberle and 10aeRX7 are working on the same car.

 

And what were the two wires that were jumpered at the relay?

 

sorry for the confusion. i am the one working on the car.

To make it easy some background on the car first.
1987 n/a chasis
s4 n/a chasis harness
s4 (1988) turbo engine and harness
s5 dash with s5 dash harness
s4 ign switch

What was happening last night was as follows:

1) I started with tracing wires back to the afm. found out that the afm was not grounding so that the circuit opening relay would allow the fuel pump to prime.
2) grounded out the brown wire on the afm connector to chassis
3) turn the key to ON fuel pump turns on, but pump didnt stop
4) engine cranked over and runs np
5) gave it a little throttle and car either flooded out or died ( possibility of maybe having pri and sec inj plugs reversed?)

just so im clear the relay is right next to the steering column( black/yellow relay 5 pin) wires in the connector
b/w b/w 2x l (blue)
2 black empty brown

so i jumped the 2 black and brown wire to each other from the connector
result is no fuel pump but engine turn over (starter wired bypassed from ign switch to str solenoid)

 

Only two wires were to be jumpered and they were solid Black wire and the Brown wire these are two separate wires as one is located on the bottom row far left (solid Black) and the Brown wire located on the bottom row far right.

This will get the pump to run full time/continously when key is turned to on. Doing this test will tell you if you have a break in the wiring especially when dealing with the Brown wire. Try this test which involves only two wires as specified. When these wires are jumpered and key to on the Blue wire in this relay will have voltage on it and this is what turns the fuel pump on. See for yourself.

The Brown wire at the AFM should not have to be grounded as you are doing. There is one of two issues at hand which requires the Brown wire to be grounded manually to turn the pump on. Either the fuel switch internal to the AFM is problematic or one of the Black wires at the AFM which provides a ground to the fuel switch is not providing the necessary ground. You can conduct some continuity tests to determine if certain wires are open or not. One would involve the Brown wire at the AFM. Disconnect the plug at the AFM and run a continuity test on the Brown wire to the Brown wire found in the fuel check connector plug. There are two wires in this plug. One is Black and the other is Brown so identify which one is the "Brown" one and do the test as there should definitely be continuity. No key necessary.

There are other tests similar in nature but do this one first. Also, you need to figure out if you indeed have the injector plugs switched in some fashion. Figuring this out should be rather easy, so ask if you need assistance with this.

 

A few more things to chew on. With the key to on the Brown wire at the fuel check connector should have voltage so check for voltage.

When you see that this Brown wire has voltage on it go to the AFM and repeatedly open and close the flapper door while you look at the voltage on the Brown wire at the check connector. This is to be done with/key to on and the AFM plugged in. What should happen? The voltage on the Brown wire should drop to zero or near zero as the flapper is opened and then return back to a higher voltage as the flapper is closed. Do this over and over and observe for the change in voltage.

If there is no voltage change in the step above then briefly focus on the other wire in the fuel check connector plug which is Black and jumper a wire from the Black wire to a suitable ground. After the Black wire is grounded conduct the same test as above and observe for changes in the voltage on the Brown wire as the AFM flapper is repeatedly opened and closed. Again, key to on.


Now to address whether or not the plugs on your injectors are correct or not do as follows. Disconnect the plug you have connected to the front secondary injector. This injector should be a Light Green/White wire. The rear secondary should be Light Green/Red. If need be remove the smallest plug on the ECU where you will find these wires and do a continuity test. No key necessary.

 

ok i will try these steps and see what happens. thx

 

well this is great, Satch thanks a ton and 10aeRX7 if you get any good results txt me asap

I love this forum

 

inj connectors are good.

 

Check connector plug. Located near passenger fender. Look for plug coming out of the emission harness that runs close to the fender.

A few more things to chew on. With the key to on the Brown wire at the fuel check connector should have voltage so check for voltage.
it does not have voltage

When you see that this Brown wire has voltage on it go to the AFM and repeatedly open and close the flapper door while you look at the voltage on the Brown wire at the check connector. This is to be done with/key to on and the AFM plugged in. What should happen? The voltage on the Brown wire should drop to zero or near zero as the flapper is opened and then return back to a higher voltage as the flapper is closed. Do this over and over and observe for the change in voltage.

If there is no voltage change in the step above then briefly focus on the other wire in the fuel check connector plug which is Black and jumper a wire from the Black wire to a suitable ground. After the Black wire is grounded conduct the same test as above and observe for changes in the voltage on the Brown wire as the AFM flapper is repeatedly opened and closed. Again, key to on.
i cannot find this 2 pin wire

 

One thing I overlooked the first time you posted this info. You said the Brown wire at the fuel check connector does not have voltage and then you state you couldn't find the two wire connector with the Black wire. Both of these wires are in the same plug so your response does not make sense. The FSM states the Brown wire in the check connector has voltage w/key to on. I checked this out on my own car and it indeed does have voltage on it. I'm thinking you didn't check the proper wire or you forgot to turn the key to on or the ground point you used in measuring the voltage on the Brown wire was not worth a damn. The alternator works just fine as a ground point.

 

ok ill re-check that, im so busy with school so takes me a while to get to the shop.

 

ok well finally got the car runing had a few vacuum leaks that needed to be capped. now the afm actually gets sucked open and runs on its own. still not sure why the pump wont prime and it takes a few seconds of cranking to start but it does.

satch thanks for the tips, great help.

 

It won't prime w/key to "on" unless you jumpered the fuel check connector or opened the flapper to the AFM. Outside of that the fuel pump will only turn on w/key to start.