AFM CEL and SI Inspection Light

[handysmurf59]

Do any of you guys know if an AFM CEL code will cause the SI board "Inspection" light to come on?

About 2 weeks ago I did an oil change and reset the SI board, as I have many many time. All the green lights came on and everything seemed well. Approximately two days later the CEL came on with a AFM code and the "Inspection" light came on at the same time. All the little green lights went out.

I performed the AFM tests as outlined in the Bentley, and they all indicate that the AFM is just fine. However, MPG is down to about 20 in the city from its usual 25. :(

I then tried resetting the SI board light. They all reset just fine and light up nice and green for about 5 miles. Then the "inspection" light comes back.
SI board is about 2yrs old with NEW Batteries.

My understanding after reading the Bentley is that these two systems are separate. SI board is for routine maintenance and the CEL is for emissions related faults.

So I think I have two separate issues that started at the same time. Can anyone confirm?

Thoughts on replacing what components first?

Thanks,
Jason

[jlevie]

The CEL has nothing to do with the SI board. What you describe can be caused by bad batteries in the SI board or a failing board.

If your AFM code was 1215, the cause could be intake leaks.

[handysmurf59]

The CEL has nothing to do with the SI board. What you describe can be caused by bad batteries in the SI board or a failing board.

If your AFM code was 1215, the cause could be intake leaks.

Bad SI batteries? These things are getting old now and even "New Stock" I think is questionable. Its not the first time I have had issues with the SI board. I had to go through about a half dozen. I will take a look at the batteries.

In regards to codes, I got CODE 1 using the stomp method. The car is a 86 325iC with the Motronic 1.1. What is this other code your talking about? What tool are you using to retrieve the code 1215?

Thanks in advance.

[jlevie]

A Motronic 1.1 DME doesn't support the stomp test, that requires a Motronic 1.3. So I don't have any confidence in the code you pulled. Codes can only be retrieved from a Motronic 1.1 with a diagnostic system.

A new SI board from a dealer will have good batteries.

[handysmurf59]

By gosh you are right! What I did was completely different. I read the codes when the key was in the on position as outlined in the Bentley manual, Chapter 6 page 36. I used the "on board diagnostic system" that was incorporated into the Motornic 1.1. The code that was given (Code 1) is listed on page 37 of the same chapter as "Air flow sensor malfunction".

Now what I could not figure out was when you follow the trouble shooting directions in the Bentley the tests on the AFM are all negative. That is, it checks out fine.

All the above quotations are from Chapter 6 of the Bentley manual. Which I am sure you are very familiar with.

[jlevie]

An AFM fault code can be from loss of signal from the AFM or data from the AFM that appears to be nonsense. The former would be a fault in the AFM, a wiring problem, or a fault in the input channel in the DME. The latter could be a bad AFM, a problem with the input channel in the DME, or could be caused by intake leaks.