@DaveCT MB AFM pot - PeachParts Mercedes-Benz Forum

ThomH · #1 12-11-2003, 08:07 AM

Hi Dave,

I can't believe it, another person with this strange Bosch part number 3430 591 017!

I tried to figure out what pot I will need, over the last couple of days.

I called MB, and Bosch but yet no answer. MB is currently checking this topic.

Now, I discovered your posting that the pot 3437 224 035 doesn't fit. Did you find the correct replacement or did you change the whole AFM? If the latter, have you investigated whether there is exists a replacement and if so, how hardly?

Cheers Tom

John Plut · #2 12-11-2003, 11:44 PM

Try www.olyparts.com. They sell replacement pots and they should know which number to use as a replacement. I had a question regarding a superceded part number and they supplied the answer. They are also one of the few (if not only) suppliers that will sell the pot independent of the airflow meter.

John

ThomH · #3 12-13-2003, 01:29 PM

Unfortunately they don't.

Meanwhile I found a thread from a guy from the Phillipines that the replacement AFM for his MB of 1986 had a pot with the number 3430 591 034. However, olyparts didn't know this number either.

HELP!!! Knowbody outside who knows the replacement number of the 3430 591 017 pot?!

Tom

daveCT · #4 12-13-2003, 01:54 PM

i never found a replacement pot for the 017, just a whole new airflow sensor from MB or Bosch a source, about $450 bucks for it .

ThomH · #5 12-13-2003, 02:02 PM

Could you maybe check the number on the pot of the new AFM? I would very much appreciate this, since the part with this number should be deliverable (I would guess).

I hope, the guy from the Phillipines just had a typo in his number.

Cheers
Tom

daveCT · #6 12-13-2003, 02:11 PM

i never got a new A/F meter , just adjusted it back to spec and got the CO just right , and found the real problems for slow speed reving was a bad CIS water sensor with a broken wire,
and the gummed up idle flow sensor with cracked tubes fixed it

whats the problem are you having with the euro 16v ??

ThomH · #7 12-14-2003, 05:37 AM

I just discovered something.

My readings with engine off:
Pin 1 & 2 AFM untouched: 4,7kOhm
Pin 1 & 2 max resistance: 16kOhm
Pin 1 & 2 in between: except idle deflection continuously rising resistance with rising deflection until max then falling - at the upper measure points the resistance falls off 1-4k after a second (digital multimeter)
Pin 1 & 3: always 4,13 kOhm

Now, how can be 1&2 > 1&3? Since the trim pot is serial to 1&3, 1&2 must be smaller 1&3 unless there is a further resistance at 2. So maybe the contact of 2 has a serious problem itself (dirt) and not only the layer on the pot?!

How did you notice that your new pot didn't fit. "Just" because the engine didn't run as well anymore or did you measure different resistances or anything else?

Tom

By the way, its a 300SL from 86