AMM Replacement Intervals - Page 2 - PeachParts Mercedes-Benz Forum

eddieo45 · #16 09-29-2004, 02:39 PM

4 years, 70,000 miles. let me repeat a question from my own AMM post (10 views, no replies). See my post

If the AMM makes the air/fuel mix richer by 18-32%, as I've read, does that mean that my fuel economy will improve by that much now that I've replaced it (my CEL was on for months!)?

blackmercedes · #17 09-29-2004, 03:18 PM

I don't think it has the mixture rich constantly, but perhaps under certain circumstances. My own AMM failure had the car running nicely with the exception of a high-load high rpm stumble. Seemingly the mixture was proper at least some of the time.

My fuel economy has not changed so that I would notice since my own AMM replacement.

I am still impressed with the economy of the aspro M111 and 722.6 combo. I went climbing last weekend and came back from Jasper doing about 150 km/h pretty much the whole 290km's from Hinton, and got 8.1 L/100km. For those metric impaired Yanks, that's 29mpg at a cruising speed of 95mph or so. Far from my best/typical mileage (speed limit driving) of 6.5L/100kms (37mpg), but pretty good considering my rate of velocity.

eddieo45 · #18 09-29-2004, 03:47 PM

well, we've been getting about 18 mpg so I'm hoping for a drastic imptovement!

mpolli · #19 09-29-2004, 05:04 PM

I would assume even with a marginal AMM, that under steady conditions the O2 sensor would pull things together, mixture wise. That MPG sounds really bad. I am really curious what could cause that. Does the thing run like total cr*p? Any theories anyone?

blackmercedes · #20 09-29-2004, 05:16 PM

Well, the C280 does not get as good economy as the C230. I called my friend Kevin who drives his C280 mostly in the city, and he said he typically gets about 12-13L/100km in stop and go.

That's 18.5-20.0 USMPG.

mpolli · #21 09-29-2004, 05:34 PM

Any opinion of Hengst vs Mann air filters? Mann is a little cheaper.

MP

fredfisher · #22 09-29-2004, 07:43 PM

I have had great luck with my C230. I really have abused and neglected it and it treats me real well. I use the cheapest grade gas and switched to petroleum based oil right from the first change. Of course, I change it sooner than the FSS says, but that is expected. I needed an AMM two years ago but didn't know it. Of course the CEL was on and that should have said something. I have owned it since new and with 175,000 miles have only had to do brakes front and back, several times, new water pump, and oxygen sensors. I changed those to try to cure the P0170 with CEL on, but they didn't fix the problem. I kind of thought the Air Mass Meter was the problem, but the universal oxygen sensors were only $50 and the AMM was $300. I gambled and lost, but changing the oxygen sensors was probably not such a bad thing anyway. I also neglected the battery level, and the plates fused and I had to replace it. Naturally that happened about a month before MBZ had a battery campaign. Of course, I took the old battery back to Pep Boys to get my seven bucks core charge back. I hope to make 300,000 in a couple years because I leased the car, then had to buy it because I had put on so many miles. I am so upside down on the loan that it HAS to last 'til 300K. Tranny has been rock solid and even shifts better with the new AMM, if you can believe it. No more slamming downshifts when slowing to a stop. I also seem to feel the car runs better with regular plugs than platinum plugs. I put in Bosch Platinums and took them out after two weeks. Anyone agree or disagree?

Tump · #23 09-29-2004, 08:24 PM

I had the MAS replaced at 70K miles under warranty at which time the dealership also replaced the ambient temperature sensor. The failure symptoms were not all that terrible, but I felt as though I had lost power. With this complaint along with my definate and specific urgings (as based on the information posted on this forum and others) they replaced the MAS.

I think the failure was due to my having over oiled a foam air filter. (If this is ever the case, be sure to clean the airbox thoroughly before taking the car to the dealer). Most expert forum discussions explained that a factory oiled K&N, etc. or a properly oiled K&N will not destroy the MAS (I am currently running a K&N with no problems) but that inexpert re-oiling and over-oiling of an air filter kills the MAS every time.

I read in the Bosch literature that the oxygen sensors should be replaced every 60K miles. This works well with the MAS which seems to fail on average at around 70K miles. (I would advocate changing each pro-actively to avoid other consequential failures). But, someone posted on another forum that the MAS platinum wire could be cleaned with electrical contact cleaner safely. That may solve some of the reasons for a MAS failure but not all.

Most other expert mechanics I've read on this forum and others say that sticking with the factory recomended plug is the best thing to do. And that a regular copper plug will allways conduct more electricity than platinum. On my car, however, with 16 plugs to change and the two plugs furtherst back in the engine requiring a mechanic to change, I opt for the long lived iridium plugs but will still change these every 50k to 60K miles. (The 100K mile claim for platinum plugs is like MB's claim for its transmission fluid -- nothing lasts forever).

daddiojiggy · #24 09-29-2004, 08:59 PM

it's late and i couldn't be bothered to read all the posts so forgive me if this has been covered:i don't understand how a filter that gets plugged will let bigger pieces through.to me, if it's plugged up that means more and more stuff can't get through - like good air.how big pieces can now get through is beyond me.please explain,thanks.
p.s. what are you doing with your sat nights now?damn lockout!

blackmercedes · #25 09-29-2004, 09:41 PM

I'm not sure exactly why, but it seems like particles on the filter become dislodged when it's full and the air can't get through as easily. Some stuff falls into the bottom of the filter housing, but some makes its way into the intake.

All I know is that my mechanic illustrated this to me, and it was very clear visually. I didn't want my intake looking like that.

blackmercedes · #26 09-29-2004, 09:52 PM

Quote:

Originally Posted by fredfisher

...but the universal oxygen sensors were only $50 and the AMM was $300.

Did you have to modify the harness to fit the non-OE O2 sensors?

And yes, most MB engines (especially M104/104/111) HATE platinum plugs.

As to Saturday nights and hockey, well, most of my weekends are spent on some mountain somewhere and I haven't watched an NHL hockey game since probably 1988 or so.

The view from my tent's door on Saturday afternoon...

shane83SD · #27 09-29-2004, 09:54 PM

5 years, 37K miles. 98 C280.
Car seems smoother after the AMM change. Last 1000 mile trip averaged around 27 MPG, with AC on.

fredfisher · #28 09-29-2004, 11:58 PM

The universal oxygen sensors come with just four wires about 36 inches long hanging off the end. I cut the old sensor wire harness in half and spliced the half with the Molex connector to the new sensor wires. The wires are color coded for easy match. Black, white, and grey and white. A little solder and duct tape, and it was done.

Also on cleaning the AMM. I cleaned mine with 91% alcohol and compressed air and before cleaning the CEL light would come on after about an hour of normal driving. After cleaning, it stayed off for alomost a day. The cleaning helped, but only somewhat.

mpolli · #29 09-30-2004, 12:35 PM

fredfisher,

I hope you didn't really use duct tape on your O2 wires!!

blackmercedes,

Quote:

Originally Posted by blackmercedes

And yes, most MB engines (especially M104/104/111) HATE platinum plugs.

Aren't the OEM plugs platinum? What is the problem with them? What do you recommend?

Mike

blackmercedes · #30 09-30-2004, 01:19 PM

Quote:

Originally Posted by mpolli

Aren't the OEM plugs platinum..?

Nope. check your manual, and go with the plugs recommended in it. They're copper plugs, not too expensive, and work MUCH better than platinum plugs. Some engines are not designed to use plat's.