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mjuu
Date registered: Dec 1899
Location:
Vehicle(s):
| ML wont shift up when 'floored' ....MAF issue??
Hi everyone,
My '01 ML wont readily shift up into 2nd gear after I 'floor it' from a standing start....it kindof gets stuck around 3500 rpm - But everything is OK in normal 'calm' driving use when the auto shifts up around 2500 rpm. You can feel the lack of power when you reach 3000 rpm and the engine really struggles to get to 3500 and beyond.
The problem only surfaces under full throttle and each expected gear change at the upper rpm point just doesn't happen unless you back off on the throttle to reduce the Rpm - and of course when you've just pulled out into highway traffic this isn't what you want to have happen.
According to my local MB dealer, its the MAF sensor causing a mixture lean out (under load) and thereby preventing the engine from reaching the extended upper Rpm gear change point. If this is true, does anybody know if these MAF sensors which proliferate on ebay are any good as replacements?
As for the codes, the dealership didn't provide them - this is what I was given/told - "Found air flow meter and stop lamp switch faulty"
Then they quoted the prices...Arghhh!
In my quest to try and source just the sensor insert, our local Bosch distributor had this to say( ...the plot thickens.)
..."This sensor cannot be purchased separately, it is part of the complete
assembly that is calibrated when assembled.
The Mass Air Flow Sensor when manufactured is fitted with the sensor F00C
2G2 02S which is uncalibrated or aligned. Laser light is used to align the
sensor with the airflow then the screws are locked. Once this is done the
calibration process is done with a measured airflow at idle and wide open
throttle. The MAF is only available as a calibrated assembly.
Please do not hesitate to contact us again if we can be of further
assistance." - Customer Service Representative, Robert Bosch (Australia) Pty Ltd
Btw, as I'm in OZ, it seems that most USA parts outlets will not send stuff Internationally for some crazy crazy reason ? (eg Wholesaleimportparts /Germanstar/globalautoparts, etc. ). At this point I'm between a rock and a hard place.
Any comments anybody - pleeeeeeze ! |
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cmitch
Expert
Date registered: Apr 2006
Location: Ala-Tenn
Vehicle(s): 2002 ML320, 2005 S430 4Matic, 2010 F150 Super Crew
Posts: 3412
| RE: ML wont shift up when 'floored' ....MAF issue??
Sorry about the late reply. Could you have a bad 'kick down' switch? It's the switch located below the gas pedal. Also, double check and make sure your floor mat hasn't pushed up under you accelerator pedal or you'll get this problem (happened to me, once). As for the MAF, you will get codes P0170 and P0173 on this (usually). You can get your codes read for free at most 'chain' auto parts stores. I don't know which stores you have in Aussie but here they're Advance Auto and Auto Zone, here. Welcome aboard!!
Edited by cmitch 12/16/2007 12:33 AM
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MADSLEG
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: ML wont shift up when 'floored' ....MAF issue??
I had exactly same symptoms when my MAF sensor went bad
it feels like transmission problem,but turn out to be a bad MAF |
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MADSLEG
Date registered: Dec 1899
Location:
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| Re: ML wont shift up when 'floored' ....MAF issue??
and BTW i didnt have any PO codes !!! |
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mjuu
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: ML wont shift up when 'floored' ....MAF issue??
Thanks guys!
Its not the kickdown switch - in fact the switch exacerbates the problem in that it shifts down , but afterwards just wont rev (up if you know what I mean) - It just kinda gets stuck at whatever Rpm it gets forced into. You then have to back off the throttle and ease the Rpm up gently. Btw, there's nothing wrong with the gearbox - given what I'm seeing, it for sure has the smell of an 'Ecu making decisions based on wayward input data' kindof problem.
I've now tried a couple of our tune up 'chains' over here, but they cant help .....over here, 'European imports' ( yes I know its a USA product in reality) suffer from the tall poppy syndrome and unless you drive a Ford or a Holden, tech support for most anything else can be decidedly 'iffy' outside of a regular franchised dealer.
So does anyone have any idea's about where I can source a new sensor insert (and that will ship it over to me )?
As I said b4, GermanStar (and others) have it, but when I called GStar they said they dont really ship International and even if they did it would cost over $100 to do so. I got the impression that it was just too much of a hassle for a $129 part ....arghhh!
Now if only I had a friend in the US....... |
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Marcelc
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: ML wont shift up when 'floored' ....MAF issue??
Sometimes the dealer himself is not too expensive for parts. I have found that, apart from some extreme exceptions, Mercedes parts are less than the equivalent VW part (ECU fan in the UK excepted).
How about trying the local Mercedes dealer?
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mjuu
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: ML wont shift up when 'floored' ....MAF issue??
Hi M,
...tried the 'stealership' - A$650 for sensor w. housing!! Maybe this is one of yr extreme exceptions?
Can you give me name/website of local dealer near you - I'll contact them to verify. |
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Tarydesign
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: ML wont shift up when 'floored' ....MAF issue??
There are two "Secondary air injection" Pnuematic valves that were blocked solid on mine. They can be found directly in front on top of the engine (Side by side of the Blower) when you remove the plastic cover. I removed and cleaned them carefully, they have a spring loaded rubber valve which was stuck shut!!
Try these first cost=$0.00 and about an hour time..
Check my thread labelled "Please Help, Engine in protection mode.."-excellent technical writeup (thanks gents&ladies).
Then try Importec for MAF, they sent mine to South Africa..
Or try:
http://germanstar.net/MAF.htm |
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MADSLEG
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: ML wont shift up when 'floored' ....MAF issue??
Here is how to clean your Secondary air injection(with pics) i did it a while ago but forgot to post it on this forum
http://www.benzworld.org/forums/w163-m-class/1348815-how-clean-seco... |
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MADSLEG
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: ML wont shift up when 'floored' ....MAF issue??
mjuu where you from ?
Edited by MADSLEG 12/19/2007 6:32 PM
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mjuu
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: ML wont shift up when 'floored' ....MAF issue??
Hi guys,
Some quick feedback.
I disconnected the MAF - now she revs up through the range properly.
But I did notice a slightly lumpy idle and when you stomp on the 'loud' pedal ( while idling) she hesitates badly and nearly cuts out.....but she's better overall.
So I guess that confirms its something to do with the MAF - either its dead or is outputting nonsense?
I'll still have a look at the air injection side for good measure anyhow.
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Tarydesign
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: ML wont shift up when 'floored' ....MAF issue??
Sorry, thats got MAF written all over it, You'll also find it won't run right when the air is cold and your sensor is disconnected, stutter stutter as you have with it plugged in, and it will actually slow down if you depress past 1/2 throttle!!
Best advise:max 1/2 throttle and if you do start to stutter, it WONT rev past 3000rpm, best you pull over and turn ignition off, wait 10 secs and restart. Usually it will run fine unless the air temp is very low (less than 5'C)
PS watch how much fuel you save (only because you'll be driving it sooo light!)
Best bet is to get a new sensor.. try Importec, they were helpfull and I was back to full speed soon enough!
Madsleg: nice write-up!!  |
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