Can a bad MAF cause a EGR trouble code? OM 606 - PeachParts Mercedes-Benz Forum

muleears · #1 10-27-2008, 07:27 AM

I know I have a bad mass air flow sensor (a new one is on the way) can this cause an "EGR flow" trouble come to trip? I can't find anything wrong with the EGR. All vacuum lines attached correctly, swapped actuators with the turbo and still no change. Are EGR's prone to failure?

#2 10-27-2008, 07:39 AM

Yes. The MAF is for monitoring the EGR's performance. If its not seeing the airflow the computer expects, it will think there is an EGR problem.

KarTek · #3 10-27-2008, 09:23 AM

It could be the EGR solenoid/actuator/whatever it's called on the left fender well. One trick is to swap it with the identical one controlling the turbo and see if the problem goes away or the turbo develops a problem.

nhdoc · #4 10-27-2008, 09:27 AM

Quote:

Originally Posted by KarTek

It could be the EGR solenoid/actuator/whatever it's called on the left fender well. One trick is to swap it with the identical one controlling the turbo and see if the problem goes away or the turbo develops a problem.

The OP said he already tried this.

My guess would be it is possible that the MAF is causing this. As long as you know there is a problem then replace the MAF and see what happens, is my advice.

BTW - There apparently is a lower-cost MAF replacement which consists only of the insert piece...I was told about this by one of the other regular posters here who used it in his car. If you already ordered a replacement then you probably don't care but otherwise you might do a search.

KarTek · #5 10-27-2008, 09:30 AM

Geez, a two line post and I missed that...

My car's not going anywhere for a while. I'd be willing to let you borrow my MAF to determine it it's the problem for the cost of shipping since you're so close.

muleears · #6 10-28-2008, 08:04 AM

Thanks, KarTek but I have already ordered one. It should arrive today. I hope this solves my driveability problems. The car has been very erratic in performance. Usually very poor and occasionaly good (but not great).

nhdoc, I had heard of the cheaper insert also but only found posts that talked about it none mentions part # or years it fits etc.

All thanks for the advice.

nhdoc · #7 10-28-2008, 11:25 AM

Quote:

Originally Posted by muleears

...nhdoc, I had heard of the cheaper insert also but only found posts that talked about it none mentions part # or years it fits etc...

This is what I have in terms of replacement part data, but have not verified it personally:

"It's a Pierberg I think for the CDI, part #6110940048, MSRP $100"

This PN corresponds to a MAF insert, which supposedly fits into the housing in the W210 OM606.962 and works just fine. Like I said, I have no personal experience with this.

muleears · #8 10-29-2008, 07:24 AM

Thanks again, nhdoc.

I installed the new one yesterday, cleared the code and the car still ran like crap and tripped the code again. So I put it away for the night. Driving it to work this morning it seemed to run better the farther I went (total 40 mi.) I'll test again at lunch. Could it just need driving to clear it out and reset the code?

KarTek · #9 10-29-2008, 09:53 AM

Have you hooked a vacuum gauge to the EGR line and verified that it's pulling vacuum when it's supposed to? Have you ever had the EGR off and cleaned it? I wonder if it's possible that it's gunked up and won't open fully...

A couple of us have had good luck with an EGR bypass which is not "technically" solving your problem but may be a way to skirt the code. For me, I didn't want the EGR blocking part of the intake.

I have a worthless EGR sitting in the garage if you want to trade, all I need one for is for it's physical presence to connect the intake to the up pipe.

TMAllison · #10 10-29-2008, 12:48 PM

Cal - The ECU has to adapt to the new MAF data being fed to it. IIRC that will take ~1hour or 50mi of typical use.

muleears · #11 10-29-2008, 01:04 PM

Just drove the car home and to the Dr. office. About another 60mi. The engine seems to run very smooth now, no surging and no misfires at all. The MAF code is gone, I'll check again later today. I still have a pronounced lack of power and the EGR code still pops up. Seems we've solved part of the problem...now I need to concentrate on the EGR. Would a malfunctioning EGR cause a lack of power? The car runs/shifts smoothly just acts as if no or limited boost and doesn't like to downshift after a slowdown. It wants to stay a gear or two too high. When I slow for a corner, coming out of the corner it doesn't downshift to get the RPM's up where there is some power.

Thanks for the help so far guys, we're getting close

KarTek · #12 10-29-2008, 03:17 PM

Cal, those were all symptoms my car had when I left a vacuum hose off of the turbo wastegate modulator but I think a vacuum leak from anywhere else would cause the same problem.

muleears · #13 10-29-2008, 04:22 PM

KarTek,
I've checked, but I'll check them again shortly. I swapped the actuators (turbo and EGR) and found no difference. Could they both be bad?
How are things in Ba HAY ma?