KevinJ

Hi all, I have had my '00 W220 S500 for over 5 years now.

Recently I have noticed the power seems to be lacking when pushing the accelerator pedal to nearly maximum or indeed maximum with kick down.

All seems fine when driving lightly or say 3/4's open throttle, but if I want to kick down and accelerate fast, the car seems to hold back and creep up the rev counter range with poor acceleration, nothing like the power or acceleration it used to have.

Infact it may actually be when the rev range reaches 4500+, as this is where the holding back/lack of power is evident.

My first thought after searching on the forum, is that it may be the Accelerator Pedal Module housing that contains the 2 senders for the ECU and gear box (I think). But upon searching it seems most people who need this part suffer from standstill accerlation problems, not when pressing hard of the accerlator.

This problem occurs in all gears at all speeds but only in the throttle positions mentioned.

I have done the gearbox reset thing, but this has made no difference (although I could not tell if the reset did actually work)!

Any ideas?

Thanks in advance

Kevin

KevinJ

My question really is, do you think the problem may be the Accelerator Module (pedal unit) or something else.

Any input would be greatly received.

Thanks

Kevin

Hercules86

i had the same problem in my car as well... but im also getting a presafe inactive code

Bernie C

Hi Kevin,
Have you tried cleaning the MAF?, my S Class was ok under normal accelleration, but hesitant at the top end - MAF affects power due to air/fuel ratio and if it is dirty this can affect performance, which in my case was at the top end, this worth a try with electrical cleaner, be very careful not to damage the MAF. Do a search on MAF cleaning there are various post on this matter - good luck

KevinJ

Many thanks for advice.

I have done some reading up on cleaning the MAF, but some reads scare me. I could get it wrong and then no more MAF.

I took a look online for replacements, and sure there are cheap £30.00 (UK pound) ebay jobs, but the official Bosch type and around £175.00.

Would you recommend I clean with MAF cleaner and take a chance and potentially leave my car dead until I obtain a new one, or just go for a new one. (Hoping this is the cause).

I have steered away from the the Accelerator Module being the cause, as every case of the forums that suffer with this seem to have problems from stand still etc. Mine is only when flooring the throttle or kick down is used.

Thanks

Kevin

Quadcammer

If you clean the maf with the correct product (MAF cleaner, specifically), you won't harm anything.

That said, I believe dirty mafs to be evident elsewhere, meaning that the car sometimes idles poorly and has poor part throttle acceleration.

Cleaning it will not hurt, but I don't think its your problem.

How many miles do you have and have you changed plugs?

KevinJ

Thanks for reply

I have around 92 thousand miles and have had the car since 72 thousand miles, over 5 years ago. (Not many miles per year!).

Spark plugs do seem a good bet. I remember a mechanic telling me it would be costly a while ago, what sort of price do you think for parts/labour?

Aren't plugs due around my mileage?

Many thanks

Kevin

Quadcammer

Plugs are due at 100k miles, but I think thats quite the stretch. The reason I feel as though they may be the culprit is that over time the degredation of the electrode and some of the crap in the combustion chamber can weaken the spark. It tends to fire ok at moderate cylinder pressure, but when you really jump on it, it either blows the spark out, or you get an incomplete burn.

So, the plugs themselves are pretty cheap, around $60 I believe. Labor is a ***** if you can't do them yourself.

What I might recommend is this. Buy the plugs yourself, and get the necessary tools. Start the DIY at the front cylinders and go as far back as you can. If you can't get the last few done, just have the shop finish up. If you can get them all done, you've saved a lot of cash.

A good shop will probably charge 3-4 hours of labor for a full plug change, so about $400-$500 US plus parts

Racin_fool

wow.. i wish i got paid that much for doing spark plug services on these cars..

as for the original problem, I would honestly rule out anything to do with the spark plugs. Usually if those go bad or become an issue, you will get a check engine light and some misfires in random cylinders. With 92,000 miles on the car, I would definitely think about cleaning out the MAF if you haven't already. I have seen some cars melt the front catalysts but generally you will get some sort of fault codes for that issue also. Best bet would be to clean out the MAF and see how it goes from there.

Quadcammer

Since these cars have 2 plugs for each cylinder, the likelihood of an actual misfire is fairly slim. In addition, with 92k miles, he's due anyway.

DTMLGND

Where is the DIY thread for plug change?

Skylaw

Waiting for you to write it.

Quadcammer

check out the 210 forum at benzworld. they have links for plug changes.

its very straightforward

KevinJ

Hi all

Problem solved, was getting P0170 & P0173 fault codes and so changed the MAF using my local trusted mechanic.

Now drives much faster, more responsive and is great again.

I am smiling when driving it hard.

Cheers all

Kevin

imimike

Hey KevinJ i was wondering if the check engine light came on for you before you found out you had to change your MAF. Because im dealing with the same problem, rough idle, and poor acceleration and i just got my spark plugs replaced about 3 days ago.... but so far no check engine light has come on ..

steadystud

Hi all,

I have the same issue with acceleration and my local trusted mechanic cannot seem to figure it out as no errors show on their computers. Not sure what the MAF is and hearing a lot about it. how much does it cost to clean out the MAF or replace it?? and how long does it take?? any DIY links on cleaning MAF ??

xlr8tin

Yes, I would say it's the MAF. Mine was bad and did the samething, when I replaced it...all better

hshmb

Hi
My w220 s320 acceleration pedal does not responding no power especially on speed breaker the issue appears .when I push the pedal a little hard while I'm driving the engine missfiring 3,4 pistones .replaced the pedal many times and changed the plugs and coils and injectors and air mass sensor still the same issue .when I restart the engine it is ok. Finally I bought transmision ECU from eBay and I coded it the problem fixed. it took longtime from me the faults in transmision ECU is implausible shift solenoid valves