alpha8a

Hi guys I had an issue with my car and was wondering if anyone could help? So my car has been acting quite strange. While driving and coming to a stop at a red light, once in a while the RPMs will just drop and the car will shut off. After that the car will start up again and drive fine. The other thing is that the car tends to idle really rough sometimes too, with the RPMs sporadically jumping up on their own. Last Wednesday the check engine light turned on also.

I gave my local MB dealer a call to ask how much they would charge to run a diagnostic on the car and to get the error codes....they said $104. That's to be expected I guess as they are a "stealer"ship. I then called a local independent MB shop and talked to their owner. This crook told me that it would cost $90 and that that fee could not go towards any possible work that may be needed on the car. According to him, it was NOT a straightforward task and would take awhile for them to do. I smelled BS already.

I remembered reading somewhere that AutoZone does it for free so I had time today to stop in there. They came out with their handheld diagnostic machine and got the code for me for FREE and within 5 minutes. SO NOTE TO EVERYONE: NEVER PAY ANYONE TO RUN A DIAGNOSTIC FOR YOU!

The code that the car generated was P0102 and that code says that there is "low voltage to MAF". Has anyone else had this issue? I tried cleaning the MAF with CRC(?) cleaner but it is still giving me issues. I looked on ebay and they had Bosch MAFs for 140 shipped. Do these things tend to eventually go out on their own and just need to be replaced? Any help would be greatly appreciated.

AMGSC

Yes they do tend to go out frequently. That's why there are so many on Ebay but be careful of the cheap imitations. Make sure you are buying a Bosch.

Martinsvi

The shop I use charges 90 for the diagnostic also and it does not go towward the repair. It is a flat charge for however many times they use it for your repair. They also charge 7 bucks for shop expenses, rags, brake clean, other odd bits. These charges are present on every service they perform regardless of cost of the repair, unless they dont use the diag tool. It is the cost of doing business. On the other hand, their mechanics are paid a straight salary, not by the shop hour manual, so if they take longer than expected you dont pay the extra time and they dont feel rushed as they can be productive but conciencious about the car they are working on. The shop is well repected and has been in business for over 25 yrs and they are literally across the street from the Mercedes/BMW/Lexus dealearship.
The autozone trick is a good one and probably can work to your advantage some of the time. I wonder can autozone order you the MAF and what would the price be?

spr

Interesting. I had a problem like car suddenly sputtering and missing then dying and after cycling the ignition it was seemingly ok- it was diagnosed to a bad fuel pump.

StangStomper

Had the same problem after replacing the MAF, still the same ****, then after after going through a million other scenarios and all the wiring, still the same, found the issue to be the "fly by wire" system was failing on the throttle body and could not get an accurate reading from the MAF...so, try buying the new MAF, if that doesnt work, you will save yourself alot of headaches, just get the new throttle body system...
If you are wondering the cost, its not cheap, then again, you shouldnt own and AMG if that is an issue

Tump43

Very timely subject. I have the exact same issue. Initially, the car would stall while idling or coming to a quick stop, unless I held the brakes with my right foot and feathered the gas with my left. I changed the MAF and at the same time I also had the plastic resin MAF holder bored out and the elbow from the MAF to the throttle body custom flowed (removed one of the internal vanes, smothed the curves and generally increased flow). This seemed to fix the problem until it started again a month or so later. I took the car in and found that I had not securly connected the elbow to the throttle body and and MAF to the elbow. Tightened everything up and the problem went away.

However, about two weeks after the tightening, maybe once every two weeks, the car does the same thing, allows the rpms to drop below the minimum at idle, surges and then stalls. It does this sometines while idling and sometimes after quick stops. Ocassionally, it will stall on each restart until I start feathering the gas and then it goes away. Is this the same issue? Did I purchase a new but defective MAF from the stealership 2 months ago and need a new one? or will I have to get a new throttle body with new a new electronic connection?

Any ideas? By the way I had the new but possiblly defective MAF out twice and cleaned it with the CRC MAF cleaner per instructions? The problem still occures infrequently. The whole issue seems to behave like a loose electrical connection -- sometimes the MAF works perfectly and sometimes it does not work at all.

alpha8a

Very interesting. Yesterday, I went outside to look at my car again because I remembered that the first time I took apart the MAF, I noticed that the elbow to the throttle body was very loose. So loose that I could easily just push it off. Well I decided to try and make a quick fix out of that to see if there were any improvements. I just took a large zip tie and tried to tighten the connection. I also sprayed the MAF with more CRC cleaner and put everything back into place. So far I've noticed that my car does drive a lot better than it did a few days ago but te car still lurches a little bit sometimes while I am at a standstill at a light.

Tump43, what you are describing is exactly what I am having issues with. So when you changed out the MAF, did the car idle and drive a lot better? BTW the MAFs can be found online new for about $140-150. I called the MB dealer to ask how much they charged and they said $380. Is your elbow on the throttle body really tight (air tight)? I think that one of the reasons for all these issues is that elbow because it just doesn't seem to fit tightly like it should.

Tump43

Alpha8a -- yes, after I installed the new MAF everything was fine. Then after I swapped the new MAF into the bored out MAF holder the problem started again. I checked with my mechanic who found the less than tight MAF to elbow and elbow to throttle body connection. He properly reinstalled/reseated these components and the problem went away for a couple of weeks. I thought everything was solved. However, since my visit to the mechanic the problem returned on two or three occasions. All seems to be fine at the moment, but I really can't trust the car in high performance driving until I resolve this issue.
Anybody have any theories?

MBtech1098

Yeah because whatever that little scan tool tells you is always the problem, right? If you guys only new the half of it.

We could sit here and argue back and forth all day, and no one would be the wiser. See people get screwed by dealers, cause they don't ask questions, and they feel intimidated when the adviser recommends additional repairs.
Dealers have a certain set of guidelines they are SUPPOSED to stick to, mandated by MB, of course not all do, and that's when you can nail them by calling the CAC. If you go to a reputable dealer, or any repair shop for that matter they will only charge the diag to diagnose, and the labor to put it in without being in excess of the book time.

So before you go and say this guy or that guy is ripping me off, you need to look twice at the work they are actually doing, cause I guarantee a good shop is not just going to run codes and throw a part at it. They will do actual testing with additional tools to be sure that part is faulty. After all they don't want to sell a repair to a customer and be wrong.

alpha8a

Alright I retract my statement about the never paying anyone to run a diagnostic for you. Yes there are times when it would be beneficial to have someone certified to do it for you besides the average Joe behind the counter at AutoZone. For me, I just wanted a rough idea as to why my car was behaving the way it was and didn't want to fork over almost $100 for it.

To Tump43, could it be possible that the bored out elbow is AFTER the MAF so that the extra airflow is throwing off the calculations that the MAF is making as to what it needs for the air/fuel ratio? That's just a guess. Maybe try putting on a stock elbow and see if the problems go away? Good to know that the erratic behavior went away after you changed the MAF though. After tightening the elbow and cleaning my MAF, the car drives SUPER SMOOTH and shifts up and down smoothly also, however every once in a while it will still surge from a stand still. I'm going to drive it a little more and see what happens before pulling the trigger on a new MAF.

MBtech1098

Agreed

Any air leak after the MAF could definitely cause a DTC to be set...although I have not seen it on a 112 or 113(only on 272 and 273) an air leak at the air filter housing where it meats the MAF will cause a DTC, usually a torn seal due to the filter housing incorrectly installed. Also one other note, always check your air filters when changing a MAF, make sure there is no crap built up(leaves, dirt, crap).

Tump43

I thought about that but, the guy that bored out my MAF and Elbow did the same to his C55 without issue and said the ECU will adapt to the increased airflow without problem. My mechanics agreed with him.

I am pretty sure that your analysis explains my problem, but why would it happen again (albeit less often) after fitment was professionally corrected and all leaves, etc. and stock airfilters were installed in the air box? Does it sound like my throttle body electronics are on their way out?

speedybenz

What sort of air flow are you reading at idle with the car in drive? If you can read this in gms/sec then I will know a little more, but I can convert the reading to whatever units I need to with my trusty calculator.

Also what is the Absolute Manifold Sensor reading with the car in Drive and at idle?

Jeff

MBtech1098

It sounds like you may have some ther problem...what thought I'm not sure without further diag. Also as stated earlier, do you have scan tool that will give you grams or kg/per sec?Throttle bodies rarely fail in any of the newer benz's.

Phil C55

For the OP, if your C55 has less than 80k miles, the MAF is part of the FED emissions warranty and is covered under warranty.

alpha8a

To Phill C55, its covered under warranty? How do I go about getting that fixed then? Do I just call up the MB dealer and tell them I suspect my MAF has gone bad and that I need it repaired?

Tump43

Jeff --

I don't think your mods have anything to do with the problem. So far everything has been ok since the last stumbles -- I also ordered a new Bosch MAF (correct part number) off of ebay for $89 delivered, just in case (I didn't know that the MAF is covered to 80k as an emissions part, is this really so?). If it's the electrical connections on my throttle body, I'll have my extended warranty cover it.

In any case my dyno dash readings at idle in park (I'll redo in Drive) are:

Intake Manifold Pressure: 10.3 in/HG
Intake Air Flow, MAF: 0.69 lb/min
Ignition Timing: -13.50 deg. BTC
Engine RPM: 639 to 672

To me it seems that I started thowing engine codes when I didn't connect the MAF, elbow and throttle body correcdtly and therefore, the ECU is taking a long time to readjust to the increased air flow. Does this make sense to you?

Phil C55

That's where I would start, this morning I read in my warranty book that comes with the car that yes the MAF is included in the Fed 8 year 80k warranty. Years ago I had a Chevy truck that was years out of regular warranty and the plug wires went bad. I took it to the dealer and said it was under the Fed emmisions parts listed and they put in a new rotor, cap, and wires. $0 charge to me.

Read that Fed warranty, lots of good stuff is covered, like crank position sensors, coil packs, plugs, wires, fuel injectors, control modules, cat convertors, O2 sensors, etc. It's worth reading.

Phil C55

Yeah it's so, but don't feel bad, most people forget about it and figure they are done after the 4 year/50k.

alpha8a

Wow Phil, thanks for the great insight. I will whip out the manual tomorrow morning and take a closer look at it and I will give MB a call to see what they will say. I never even heard of this warranty before.

speedybenz

Marc,

All your readings are in line with specs. I have run the set-up you have for 2 plus years without any problems like you have discussed, unless I get a small to medium air leak. An air leak will show up on your MAF readings as a lower number and it will affect your MAP sensor too and give you higher readings around 13 to 15 in/Hg.

I would take your car for a good hard drive so the ECU can complete the relearning and adapt to the new parts.

Jeff

Tump43

Jeff

I agree. The car is fine so far. It seems, however, that I need to get you to do my throttle body sooner rather than later. My dash dyno readings at idle and in Drive are substantially similar and are:

Intake Manifold Pressure: 10.9 in/HG
Intake Air Flow, MAF: 0.61 lb/min
Ignition Timing: -15.0 deg. BTC
Engine RPM: 537 to 549


I'll see if I can escape my wife's notice and get you the TB soon!! (In my house it is verbotten to spend money on anything other than shoes, boots, purses, lingerie or jeans and it is a capital offense soup up an AMG (assuming I have been forgiven for buying it in the first place)).

alpha8a

Alright so here's an update for everyone. I called 3 local dealerships and they all said that thet the MAF is not covered under the Federal Emissions Warranty. I even called the 1-800 number and they couldn't find anythign either. Phil, do you have any documentation that shows that MB is supposed to cover my MAF sensor?

Phil C55

Yes I do, it's my 2006 MB warranty book that came with the car. In the Fed emmisions section there is a page that lists components that are covered and the MAF is listed. Do you have the books that came with your car?

alpha8a

Phil, I am out of town and I do not have access to my manuals. I'm also not even sure if I have that warranty book as I got the car used. When I called the 1800 MB number, the lady said she was looking at the warranty booklet and could not find the MAF listed under what was covered by the FED. She, along with a few other service advisers, said only the catalytic converters, engine management sytstem, and a few other things were covered. Is there anyway you could post of send me a pic or scan of that specific page?