mass airflow sensor - BMW Forum

congalaig · 02-05-2012, 04:10 PM

Hello to everyone
I've another '98 525tds. They're a great car. I've had a faulty mass airflow sensor for a while, and a problem starting the car... count to ten before turning the key! I pulled the plug on the mass airflow tonight to make sure its the problem. It is. The car went like a rocket. Just wondering...hoping that's also the problem with the slow start.?? I've replaced the battery, fuel pump in the tank and no better. Any ideas???

Lord Vader · 02-05-2012, 04:51 PM

What kind of noise does it make when you try to start it?

brettski · 02-07-2012, 05:14 AM

If you leave the AFS disconnected the engine management system will just ignore that input and work from the remaining sensors. Try starting the car without the sensor and see what happens. After a couple of days you'll know one way or the other.

congalaig · 05-28-2012, 07:31 PM

If I don't do the count it'll turn for ever and nothing kicks in. Sometimes when its hot it'll start straight off and other times it'll turn for ever and then I have to do the count

brettski · 05-29-2012, 04:36 AM

Don't look at me weird for asking this question, does this delay coincide with the operation of the glow plugs (if your car has them)?

fatcatsailor · 05-31-2012, 08:30 AM

I believe I may have this problem to. On take off it is very sluggish and it pulsates getting up to speed. Does anyone think this is the problem? New plugs and very well maintained. Starts good still. Where is the MAF located. I have read some people clean them and it works for a while. So if I find them and unplug them it should tell me if this is the problem? It won't spin the tires and barely spin on gravel even. Its a 2000 528i

Lord Vader · 05-31-2012, 02:38 PM

Your MAF is located behind your air intake filter, and before your intake manifold.

If you want to spin your tires on gravel have you turned off the traction and stability control?

fatcatsailor · 05-31-2012, 09:32 PM

No I didn't but its is a dog. Now my check engine light went out and most of the power is back. Seams when I rod on it a little, it screws up but then I take it easy driving a while, and runs better. My light came on yesterday but today it went out. Need a scan tool I guess. I really don't think I am getting the power this car has because my 300m blows it away. If I unplug these MAF sensor's to check it, it will have full power and why? I can still feel it pulsate at half throttle while climbing in speed.