Failing/Dirty MAF?
Thread Starter
MBWorld Fanatic!
Joined: Feb 2009
Posts: 1,375
Likes: 8
From: Seattle, WA
C55
Failing/Dirty MAF?
Hey guys, been a while (again) and bought a house a couple months ago so now all my cash has been going into furniture, kitchen crap and other house items
Anyways, recently the car has been acting funny. A few days ago the car's idle was odd and then it kinda jerked at a low rpm and then turned off by itself after a minute or so. I restarted it and there was no problem. I did some research and it looks like it might be a bad or dirty maf?
Should I just take it out and try to clean it first before getting a new one? It had K&N filters on it for a while but I took them off and put oem ones early this year, hopefully they didnt get the MAF too dirty.
Opinions?
Anyways, recently the car has been acting funny. A few days ago the car's idle was odd and then it kinda jerked at a low rpm and then turned off by itself after a minute or so. I restarted it and there was no problem. I did some research and it looks like it might be a bad or dirty maf?
Should I just take it out and try to clean it first before getting a new one? It had K&N filters on it for a while but I took them off and put oem ones early this year, hopefully they didnt get the MAF too dirty.
Opinions?
Member
Joined: Mar 2010
Posts: 139
Likes: 5
From: PMW
2021 GLE450, 2005 C55, 1990 500SL, 1991 300E, 2006 BMW M5
I recently started having what sounds like the exactly the same issue.
In DFW, the mornings have been in the mid 30s (degrees F) to low 40s.
When I start the car in the morning, it runs fine, but when I shift into reverse to back out of my driveway the engine will start to stutter and the idle will get rough.
Then, lets say I drive to an intersection, with the engine still warming up, I can be at a stop light, transmission in drive, waiting for the light to turn green... and the engine will surge to about 1000rpm for a brief instant before dropping back down. Sometimes it will bounce between 500 and 1000 RPM and cause the car to shake forwards and backwards a little bit. I have to make sure I press the brake pedal down a bit more than usually as the car can break free of its grip and lurch forward if I am not careful.
Sometimes off the line the engine will be lumpy in the sense that if I apply a very consistent pressure on the throttle for a gradual acceleration, the car will hesitate for about 3-4 cycles.
(light turns green, I apply throttle, 800 to 1000 rpms, then 1st hesitation, drops to 900 rpm... then surges from 900 to 1100 rpms, then 2nd hesitation, drops to 1000 rpm... then surges from 1000 to 1200 rpm, 3rd hesistation, drops to 1100 rpms, but then accelerates smoothly from then on out.
I have not experienced this problem if I restart the car from a warm or hot state. It so far has only occurred when starting the car from an cold state and either fixes itself after a few miles or after a few miles and a restart of the engine.
As the car warms up, this issue seems to either fix itself without any intervention or requires 1 restart of the engine. This leads me to believe it is a sensor issue. I suspect the MAF or one of the wheel speed sensors. (Could it be transmission related?)
There does not seem to be any issue when I am at a speed of at least 10 miles per hour and applying throttle to accelerate. Even coasting at a decent speed such as 30mph seems without issue.
Thank You
2005 C55
In DFW, the mornings have been in the mid 30s (degrees F) to low 40s.
When I start the car in the morning, it runs fine, but when I shift into reverse to back out of my driveway the engine will start to stutter and the idle will get rough.
Then, lets say I drive to an intersection, with the engine still warming up, I can be at a stop light, transmission in drive, waiting for the light to turn green... and the engine will surge to about 1000rpm for a brief instant before dropping back down. Sometimes it will bounce between 500 and 1000 RPM and cause the car to shake forwards and backwards a little bit. I have to make sure I press the brake pedal down a bit more than usually as the car can break free of its grip and lurch forward if I am not careful.
Sometimes off the line the engine will be lumpy in the sense that if I apply a very consistent pressure on the throttle for a gradual acceleration, the car will hesitate for about 3-4 cycles.
(light turns green, I apply throttle, 800 to 1000 rpms, then 1st hesitation, drops to 900 rpm... then surges from 900 to 1100 rpms, then 2nd hesitation, drops to 1000 rpm... then surges from 1000 to 1200 rpm, 3rd hesistation, drops to 1100 rpms, but then accelerates smoothly from then on out.
I have not experienced this problem if I restart the car from a warm or hot state. It so far has only occurred when starting the car from an cold state and either fixes itself after a few miles or after a few miles and a restart of the engine.
As the car warms up, this issue seems to either fix itself without any intervention or requires 1 restart of the engine. This leads me to believe it is a sensor issue. I suspect the MAF or one of the wheel speed sensors. (Could it be transmission related?)
There does not seem to be any issue when I am at a speed of at least 10 miles per hour and applying throttle to accelerate. Even coasting at a decent speed such as 30mph seems without issue.
Thank You
2005 C55
Member
Joined: Mar 2010
Posts: 139
Likes: 5
From: PMW
2021 GLE450, 2005 C55, 1990 500SL, 1991 300E, 2006 BMW M5
Did some more research,
I have eliminated the Crankshaft Position Sensor (CPS) as the culprit since the symptoms are opposite of what is going on.
From what I have been reading, the CPS could be a possible cause if the car would act up as it got warmer/hotter. In my case, the car only acts up when it is cold.
I have eliminated the Crankshaft Position Sensor (CPS) as the culprit since the symptoms are opposite of what is going on.
From what I have been reading, the CPS could be a possible cause if the car would act up as it got warmer/hotter. In my case, the car only acts up when it is cold.
