1995 960 - Car runs rough with Mass Air Sensor

tmeeks · Post by **tmeeks** » 06 Apr 2014, 21:29

I have a 1995 960. In Aug 2013 it started stalling out when driving. I checked the Diagnostic codes and itshowed a 2-1-1 code. I replaced the Fuel Pump Relay and the Ignition Control Module. That didn't fix it, so I took it to a shop. He replaced the Mass Air Flow sensor and cleaned the ground wires.

The car drove fine for a week, then started showing the same symptoms.
I took it to another shop and they replaced the first MAF with a Bosch Mass Air Flow Sensor.
I then took it to a Volvo Dealership. After 2 weeks of diagnosis, they've determined that the car runs fine WITHOUT the Mass Air Flow Senor plugged in and runs rough with the Mass Air Flow Sensor plugged in.

The Volvo dealer wants to do a full tune up, spark plugs, coils, etc.
I have spent more than I want to. Not sure what to do next?
Suggestions?

thanks,
Tim

danr960 · Post by **danr960** » 07 Apr 2014, 08:00

Generally, if the engine runs better with the MAF unplugged, that means a bad MAF. But in your case it looks as though two new MAFs made it run better but just for a short time. Two things come to mind, bad wire connectors, meaning, corrosion somewhere between the ECM and the MAF. Use an ohm meter and trace each wire back to it termination using a wire diagram. I believe in the '95 there is a midway plug connector between the MAF and ECM. So it will have to be done in two stages. But maybe that might be the connector causing your problem and just the act of unconnecting and reconnecting will bring it around. If not then you will have to continue from the midway plug to the ECM plug under the dash.
The other is a bad ECM, which replacement is the only option. This cause would be rare, but not unheard of.
I would spend the time tracing the wires, looking carefully at all plugs and wire going into plugs looking for marginal contact, pins that may been pushed back out the plastic connector.

DanR '94 964 392,000 miles (158,000 on the new engine)
'08 S60 T5 84,000 miles

Post by **jimmy57** » 07 Apr 2014, 08:16

Crankcase vent system blockage on that car can lead to oil vapor backdraft when engine is off that will coat MAF.
The MAF does go through the gang plug in the fusebox underhood on the left behind air cleaner. That is the big sort of rectangular plug with a combo philips/10mm bolt head in the center. Uncsrewing the bolt will dicsonnect it and screwing it together until it clicks will put it together correctly.

tmeeks · Post by **tmeeks** » 07 Apr 2014, 11:17

Dan & Jimmy,

Thanks for the replies. I will pass along to the technician.

One more question. The car broke down about 350 miles away where my daughter is in college. If I decide to just drive it home with the MAF unplugged, will this cause any damage to the car such as the plugs?

thanks,
Tim

danr960 · Post by **danr960** » 09 Apr 2014, 15:30

tmeeks wrote:Dan & Jimmy,

Thanks for the replies. I will pass along to the technician.

One more question. The car broke down about 350 miles away where my daughter is in college. If I decide to just drive it home with the MAF unplugged, will this cause any damage to the car such as the plugs?

thanks,
Tim

Not it will not cause any damage, after awhile, the fuel mixture will be rich, which over time will kill the cat, but for a few hundered miles shouldn't be a problem.

DanR