Air flow sensor temperatur sensor

[tjbick]

I am still working on my 84 944. It starts and then stops within two seconds. The problem comes and goes. So I tested my AFM and it passed. However the temperature sensor inside of the AFM flunked as my olm meter scale did not move at all. Since you have to buy the AFM to get the temp sensor should I do IT? I was going to look for a good used one as the rebuild Pelican sells has a poor rating. Will the temp sensor caue this problem?
Thanks for any help.
TJ

[John_AZ]

I once wasted a ton of time trying to fix an antique tube radio.
I was sure it was a capacitor.
I ordered the hard to get part and waited weeks until it could not be found.

I then started all over and found I did not adjust the signal strength correctly.

Moral---Why do you think it is the Temp Sensor in the AFM?
This is an uncommon item to worry about.

Here is a good explanation:
interesting phenomenon

GL
John

[tjbick]

John:
I was told by this forum that the AFM could cause a start then dies problem. I removed the AFM from my vehicle and it passed every test but the temp sensor in the AFM flunked. So are yuo saying I am on the wrong path? And if so what is the right one for my problem?
TJ

[John_AZ]

In the link I provided, did you try the ice cube test to check if the AFM temperature sensor was bad?

In your earlier post I agreed it could be the AFM.

The usual AFM problem is the connector. Dirt, oxidation, cracked connector, wires or the wire sheilding is cracked.

The next issue is the path of the sliding arm. It wears down with constant use. The solution is to move the arm. There is also an updated ground. FRWilk covers the AFM in detail.

You found the AFM passed every test except the Temp Sensor--see if it passes the ice cube test.

Here are a couple suggestions for "car starts then dies immediately"

Car starts then shuts off immediately

GL
John

[tjbick]

Thanks John. I put the AFM in my freezer overnight and will test it today.

[tjbick]

Ok so I took the AFM out of the freezer to perform the icecube test. I have no resistance between the outer two pins at all. This is the same result I got when the sensor was warm. According to my Haynes manual the AFM needs to be replaced as that is the only way to replace the air temperature sensor inside of it. Do you guys agree?
TJ

[John_AZ]

tjbick,

What resistance reading did you set your VOA meter at?
I have a cheap-free Harbor Freight meter I set at 200K Ohms.

Here are my results. First pic is room temp and then I put ice next to the temperature sensor.





I removed the ice.
Resistance as the AFM temperatur sensor warms up...







Retest your AFM using ice and set the resistance higher.

BTW, I am now on the clock

Donations at any food bank are acceptable.

GL
John

[tjbick]

I made a mistake but something for all of us has come out of it. I was testing my AFM and it tested fine. Then I tested the air temperature sensor inside the AFM and I thought it flunked. My mistake was I used the x1 scale on my olm meter and when I switched to the
X1K scale the temerature sensor was within specs. While I had it out I refurbished my AFM. While the car is running now I think I may still have the problem which comes and goes. I will replace the fuel filter next. I wanted to thank John for all of his help.
Now here is the neat part while looking for a used AFM for a 1984 944 I found a place that has two 944's and only wanted $60 plus shipping for one. The place is Rich Import in KC and their number is 800-448-4198. The guy was willing to exchange defective parts as long as you payed the shipping. I hope this will help one of you find a needed part.
I am going to change my fuel filter which is very old maybe even 60,000 miles and hope that fixes the problem.
TJ

[John_AZ]

Thanks for the reply,

Here is a tech tip from 9XAuto:


http://reviews.ebay.com/Porsche-944-968-Modifications-and-Repairs_W0QQugidZ10000000008344064


GL
John