ECU glitched? Your thoughts please.

Steve_Perry

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Well today on the usual drive to work my car played up on me. :(
The symptoms were really weird.

- Very lumpy/bumpy idling.
- The car couldn't travel faster than approx 15 to 20 mph :crazy: :confused:
- 0 to 20 acceleration took forever, the car just seemed to sit at approx 3,000 rpm and not accelerate at all and that was with the gas pedal full to the floor with kick-down too.

Suffice to say the car was really rough and very ssssllllooooooooww, she was not happy at all. The only way I could describe it - imagine being stuck in 4th or 5th gear with only 4 out of 6 cylinders running.

After approx 800 yards of staggering/crawling and building up a queue behind me I pulled over into a bus-stop lay-by. I put the car in neutral and the idle was that rough I thought the car was going to cut out but it didn't. Anyways, before calling out the AA etc I did the usual computer reset ritual, I switched off, took the key out of the ignition, waited 30 seconds before switching on again.

After switching the car back on she was back to normal, :rolleyes: :crazy: it was like nothing had happened :mad:

I'm guessing the ECU had just had a bad moment, kinda like when Windows gets the blue screen of death.

Would the ECU error log have this event stored in it? Any of you gents suffered from this? Any other thoughts or comments?

Thanks guys,

S.
 

Koolvin

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disconnect your battery for at lest 10 mins....
 
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Steve_Perry

Steve_Perry

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Originally posted by Koolvin
disconnect your battery for at lest 10 mins....
Thanks K.,

What will that do exactly? I presume disconnecting the battery won't clear any fault logs?

S.
 

Guy

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Originally posted by Steve_Perry
Thanks K.,

What will that do exactly? I presume disconnecting the battery won't clear any fault logs?

S.
Steve, this is from C32 website - can't say I've done it, but a number of users claimed it worked for them -

Purging the bad data

When the factory designed the software for the engine and transmission
mapping, it was obviously based on the hardware parts being completely broken
in. Yet our car's computer has been building up a "learned" database during
breakin, when the parts are wearing in to their "set." Thus, there may be
incorrect relationships between what the engine and transmission are doing
compared with the design. The factory says it takes at least a 1000 miles to
breakin, but I have waited for 2000 miles to pass before purging the bad
data. The time has arrived to reboot the operating system, just like Windows.
It is quite a simple process. Just disconnect the battery for about 30
minutes. 30 minutes is a good amount of time to be sure that whatever can be
purged, will be purged. After reconnecting the battery, and performing the
four "sync" operations in the handbook and resetting the "settings" and time,
everything is back to normal. Drive around for a few miles, and the good data
will have been learned.
My results are fantastic. The transmission shifts are now perfectly torque
managed the way AMG designed them (eliminating the abruptness I had on
1st-2nd at about 3000rpm). The occasional delay in locking up the torque
converter in 2nd and 3rd gear is gone (sounded like slipping the clutch on a
manual transmission). The engine idle is smoother (it sounded a little lumpy
before). The throttle response is sharp (feels like another 5 hp has come
out). I have done this purging, i.e., temporary battery disconnect, on my
last 10 new cars. For some, the results were dramatic (like this C32), and in
others, hardly anything was different. It probably depends on the individual
car. A mechanic told me about this trick back when on-board- diagnostics
(OBDII) started getting complex in the mid 90s.


Hope this helps :)
 
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Steve_Perry

Steve_Perry

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Ahhh... Many thanks Guy and K.

In addition to re-calibrating the electric windows for one touch and re-calibrating steering for ABS/BAS/ASR as discussed by Wheelie is there anything else that needs to be done after battery reconnection? Guy, I note your post reads 'After reconnecting the battery, and performing the four "sync" operations in the handbook and resetting the "settings" and time, everything is back to normal.'

Also will the fault logs be cleared on a '30 min power down'?

Thanks again peeps,
S.
 

Guy

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Originally posted by Steve_Perry
Ahhh... Many thanks Guy and K.

In addition to re-calibrating the electric windows for one touch and re-calibrating steering for ABS/BAS/ASR as discussed by Wheelie is there anything else that needs to be done after battery reconnection? Guy, I note your post reads 'After reconnecting the battery, and performing the four "sync" operations in the handbook and resetting the "settings" and time, everything is back to normal.'

Also will the fault logs be cleared on a '30 min power down'?

Thanks again peeps,
S.
As I undestand it, fault logs are not erased.

The 4 'Sync' operations in the handbook are
  1. set the clock
  2. reset the windows
  3. reset the sliding/tilting sunroof
  4. reset ESP by turning steering wheel from lock to lock with engine running
    [/list=1]

    HTH :)
 
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Steve_Perry

Steve_Perry

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There's something wrong with the car... :(

I disconnected the battery for 30mins this lunchtime after popping out for food, the car behaved while out at lunch.

After reconnecting the battery and performing the sync operations I thought I'd take the car out for a quick test run :(

She could barely make it out of the car park. This time it was like the car didn't know what the throttle pedal was doing. The engine wouldn't rev no matter what tune I played on the accelerator pedal and the car was struggling to make 10mph. I carried on into the next road from where I work and left the car with the Swansea MB stealership for fault diagnosis. :(

What a pants day! :rolleyes:

S.
 

Shude

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Originally posted by Steve_Perry
What a pants day! :rolleyes:
Sounds like it! Typical that the engine etc is working perfectly but a few misplaced 1s and 0s on a chip buried somewhere in a computer stops it from functioning! :rolleyes:
 

Guy

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Sorry Steve!

Fingers crossed for a quick and inexpensive solution...
 
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Steve_Perry

Steve_Perry

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One Happy Bunny!

I spoke to George Fraser over the phone and described the symptoms to him. He told me the most likely cause was a faulty air mass flow sensor and told me what prices to expect from MB... between £205 - £260 for the part and approx 1 - 1½ hrs labour, all plus VAT. He said there could be other causes but hoped it was the air mass flow sensor as that was the cheapest fix overall. E.g.: ECU up the duff - £1000 or a drive-shaft sensor (?) a cheap part at approx £50 but horrendous labour charges to strip and replace part.

About 5 minutes (approx 4:20p.m.) after talking to George I spoke to the MB dealership. They informed me the air mass flow sensor had failed, the part was £201+VAT and that they had one in stock and would I like to procede with the repair :D :D The answer was a big YES!

The car was ready for me by 4:45p.m. Total bill £201+£52(labour)+VAT :D I haven't even paid the bill yet because they hadn't time to prepare one. They let me take the car and said "pay the bill when it turns up in the post, probably Friday". :rock: :bannana: Three cheers for George and my local dealer :cool:

I think this mass air flow sensor has been on it's last legs for a while now because what a difference in driving the car on the way home :eek: :D :D It's like a totally different beast. It feels like the car has gained horsepower and the gear changes have become silky smooth again (I thought the gear changes had been sloppy of late).

One happy bunny, and faith restored in MB dealers,
Thanks again all,

S.
 
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Steve_Perry

Steve_Perry

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Originally posted by Simon
Where is the air mass flow sensor located?
I don't have a clue?!? but if I had to guess... air inlet manifold?

S.
 
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Steve_Perry

Steve_Perry

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Originally posted by Fudger
Guys, have alook at this post for location in a W208. Must be similar in your 202's I would suspect. The picture is in the 7th reply down the post by the way.

http://forums.mbworld.org/forums/showthread.php?s=&threadid=43790&highlight=mass+sensor

Steve, do you have a K&N filter?
Fudger,

Nope I just have a standard MB OEM air filter. That engine and bay look almost identincal to mine apart from bodywork colour and differing air filter housing.

I really do think my sensor has been gradually failing over a period of months. I've just taken my motor out for an evening drive... freakin' awesome :crazy: :rock: :D

Imagine having a tiny little bit of HP nibbled from your car everyday for a period of months. So small that on a day to day basis you can't really tell much difference. But a few months down the line you could swear that "your car used to be better than this". Heh then imagine getting all your lost HorsePower back in one lump package... Well that was tonight :D :cool: The car felt and drove like it had another 20-30 BHP under the bonnet. Heh well that's how it felt to me.

S.
 

Fudger

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That's good news Steve.

It's the first time I have heard of a degradation in performance as you have explained in this thread. I am please for you that it's all sorted out now as it must have been frustrating ;)
 
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Steve_Perry

Steve_Perry

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Originally posted by Fudger
That's good news Steve.

It's the first time I have heard of a degradation in performance as you have explained in this thread. I am please for you that it's all sorted out now as it must have been frustrating ;)
Thanks Fudger :)


'it must have been frustrating'
Da.mn straight ;) especially at the end when the performance was 10mph top speed and 0-10mph over 5 to 7 seconds. :p

S.
 

GrahamC230K

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My car just died. Same symptoms, done about 25 miles with a K&N filter.


Me buggered. :(


Shiet happens peeps, dont fit a K&N just in case.
 

GrahamC230K

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OK peeps, still in trouble.


The part that the AA man told me was the MAS and I removed last night and inspected (looked OK to me!) was this:




Now this is a different location to normally aspirated MB's.

Is this the MAS? - note Air Mass Sensor, NOT air flow meter


If so it is a long way from the air box to get contamination I would have thought - not like other cars where the MAS is straight off the air box pipe.


Got about 5 minutes from 8am this morning to ring around and try and get some help before my last free ride on an AA lorry wants to know where we are going.
 

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