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Old 11-21-2014, 01:47 AM
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oldtrucker oldtrucker is offline
BMW Mech (70's) Germany
 
Join Date: Jan 2014
Location: San Diego County
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Hi NosserW124,
Quote:
I did pull codes last night with the magic button (it's a CA emissions car) and its throwing the following:

10 - Voltage at hot wire mass air flow sensor too high/low
20 - Speed signal not present
Cleaning the MAF/MAS could do the trick, however, they have electronics built in e.g. at least an OPAMP. Technically this is not going to fail as long as it doesn't get abused.

Depending on brand or country of origin, the Hot Film may not be there and is replaced with a resistor and a wire. They work the same, are a lot cheaper than the OE part, but may have larger tolerances, some people don't even want to touch them.
I found, that the low cost MAF's are already putting out some voltage without airflow. Also, they can be electrically noisy, which is probably due to the low quality of OPAMP's in the circuit. (Sheep, sheep, sheep)

Is your speedometer needle jumping large distances?
If it does, the speedometer cable may not be seated properly at the gearbox end or it simply got kinked.

My second guess would be the speed sensor (Hall Sensor) mounted on the backside of the instrument cluster.

On the other hand, these codes don't cover the high CO and HC values, they would trigger for sure an open loop code, adaptation impossible.

Did these codes possibly come from pin 3 e.g. built in LED
Quote:
magic button
Or do you have a LED Count Reader and got them from Pin 8 (Pin 14 got only 15 codes for this model)?

HFM (Pin 8):
<20> Self-adaptation at idle speed or upper/lower partial load at rich or lean limit.
<10> O2 Sensor (after TWC)voltage too high, circuit open or voltage implausible
would make sense.

I always get confused with this mix and match stuff and if it is that then this or that etc. plus digital or analog.

I think cleaning the MAS and replacing the O2 Sensor will get you somewhat ahead, if not fixing it.
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Norbert

Last edited by oldtrucker; 11-21-2014 at 02:07 AM.
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