Calling all DMEs - need a favor
 

John Walker is suggesting my problem is my AFM.

I am having a VERY rich running (black smoke) and previously was an intermittent failure isse.

All the sensors, including the AFM are checking out according to Bentley. The reference sensors also produce > .1 volt AC when running (spec per systemsSC.com).

The AFM checks out, running with variable voltage, and variable ohms resistance when I move it manually.
John Walker suggests it is still the AFM, while I think it is the computer.

If a fellow DME Pelicanite, can do me a favor and
1) confirm their cars runs OK
2) disconnect their AFM and tell me the results at idle?

If you live in the Sacramento area, would you be willing to loan me your DME computer? Please? :confused: :eek:

Thanks to one and all!
Nick

My symptoms weren't the same as yours but you may want to review this thread - http://forums.pelicanparts.com/porsche-911-technical-forum/169758-88-bucking-rough-idle-long.html as it has info on AFM testing, esp. Steve W. post.

Good luck,
Bill

Thanks for the reply, I have read and read and read. I have also posted with little to know help other than "another shotgun DIY-er" :rolleyes:

Hence, I have checked ALL my SENSORS and they are in specifications!

John Walker suggested the AFM. So I need to borrow an AFM and/or a computer. John Walker and SystemSC says this is really the only way to be sure. :(

Or else I can send my computer to systemSC for $85 and they can test it. :(

I'd be willing to disconnect my AFM and tell you what happens, but I have no idea what to do.

If you are experiencing a hunting idle like I was, I am convinced your problem is NOT the DME, and it IS the AFM. I dismantled my AFM and discovered a worn spot on the resistive material that affected the return voltage. I paid about $300 to have my AFM "restored", which eliminated the problem, once I realized they send the unit back with a very rich CO mixture setting. Once the CO mixture was performed with the gas analyzer, I have had no issues.

Check that a FI is not stuck open. Also, a Fuel Pressure Regulator could fail allowing gas to flow into the vacuum side of the FPR and then into the intake manifold.

Thanks for the replies everyone.

I took the Reference Sensors out and cleaned them. One of them has the rubber insulation all coming off. So now the ground shielding wire is visible but still covered in a plastic wrap.

I still have the same problems.

Before I had an intermittent computer power or ignition problem NOW it runs rich and hardly idles, almost like one or two injectors are open for unknown reasons. How do I check to see if one is stuck open? Pull them out?

I guess I will double check and pull my AFM tonight and use a 9 volt battery...
I did this four years ago, and I do have a flat spot, it's very small about 1/2 into the vane. As I recall, there was no visible or noticeable wearing on the sweeping area.
The AFM puts out voltage at the computer when the car is idling and running at different RPMs so I am still having a hard time thinking this is my problem.


HUGHR- the AFM is an oblong connector just to the left of your Air cleaner and black box. SmileWavy
http://www.pelicanparts.com/catalog/images/fuel_injection/new_images/fi_1986-89_1-07-00b-1.jpg

Reconfirmed,

I bench tested the AFM with a 9 volt battery and it sweeps as expected - GOOD.

Have you checked all of the grounds? Seems to me there was an issue w/ a temp sensor not being completley grounded. There was an update to the sensor or wiring.

Thanks for the reply Bill.

Yes, I have the updated 2 wire CHT sensor. It checks out good at the DME harness.

I will be borrowing my friends DME computer tonight. Even though he has a "piggyback" computer.

I was told it should still be "OK" by his mechanic who installed his computer and upgrades.

I just want to see if I get the dramatic changes I am expecting with a different computer.

This friend does NOT have an AFM he has the cone MAF intake. So I am not sure if I will see a difference or not. :(

Anybody willing to DISCONNECT THEIR AFM and see how their car idles without it?

I use to have alot of idling and cold start problems on my VW Corrado (digifant) Always ended up having to change out the coolant temp sensor.EFI would think that it was always cold. It might be worth a look.
Glen

Also are you checking your sensors when the car is cold or warmed up?

I have an '85. Show me what to disconnect and what to check and I'll do it.

Rick- the AFM is an oblong connector just to the left of your Air cleaner and black box.

This is a pick of the AFM itself. The connector is plugged into the "front" of the car. It is very apparent when you look at the AFM. It has five connectors even though only four are in use.

http://www.pelicanparts.com/catalog/images/fuel_injection/new_images/fi_1986-89_1-07-00b-1.jpg

You need to stop wasting time & effort and either borrow a DME unit or send to
Pelican for testing.

I live in El Dorado Hills. If you want to drive up, you can try my DME. PM me if you are interested. I know the frustration you are going through......

Thanks for the reply and...enthusiasm Loren.

I got a friend's 86 DME but he has "THE PROGRAM" and it doesn't work, it sounds like it's getting spark but no fuel.
I presume the wires sticking out of his DME need to go ... somewhere.

PM'd ya' 84toy!

FYI -

BAD COMPUTER...

Swapped it with a newly found friend's computer.