Auto gear box not kicking down, where's the power gone?

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Nexus30

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Apr 27, 2008
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Lancashire
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Hi, I'm the proud owner of a 2001 C270 CDI Avantgarde but have started to encounter a problem and was wondering if there's anything I can do before getting the wallet out.

The auto box is very smooth but over the last 2 days it has developed a intermittent fault. The car wont accelerate with any gusto? The kick down refuses to work and just normal acceleration is slow (almost like the turbo's not kicking in?) The fault is through all gears but you can eventually reach a sensible 75/80 mph without the engine sounding like its having any issues.

I have found that sometimes if I stop the car, switch the engine off, remove the keys and let her rest for a while that when I start the car off again its fine and then othertimes it sorts itself out for a while then goes again???

Any advice would be greatly received, Thank you.
 
Hi, I'm the proud owner of a 2001 C270 CDI Avantgarde but have started to encounter a problem and was wondering if there's anything I can do before getting the wallet out.

The auto box is very smooth but over the last 2 days it has developed a intermittent fault. The car wont accelerate with any gusto? The kick down refuses to work and just normal acceleration is slow (almost like the turbo's not kicking in?) The fault is through all gears but you can eventually reach a sensible 75/80 mph without the engine sounding like its having any issues.

I have found that sometimes if I stop the car, switch the engine off, remove the keys and let her rest for a while that when I start the car off again its fine and then othertimes it sorts itself out for a while then goes again???

Any advice would be greatly received, Thank you.

Welcome,

If Televisions advice doesn't work out (which it should as it does sound like a MAF issue) you can always let Ian B Walker have a look at it while you are located in Lancashire. Click the link in my sig for more details.

We also have a regional get together in the Northwest once a month, why don't you come along?
 
Hello and welcome.

Your fault is 90% sure to be the MAF air filter.

Its 14 in the link,, sometimes by unplugging it the engine regains some power again, see if it drives better unplugged

Not necessarily.

I've seen many CDIs that trip into limp mode, various cases ranging from the very simple leaking air intake pipes, EGR Valves, inlet port motor.

Best bet for these cars is to plug it into diagnostics as the MAS on the diesels nearly always brings up a fault code. No point disconnecting it as it will log a fault and make future fault finding more difficult.

Also its not a 100% guarentee that disconnecting the MAS will actually make the problem any different. I've had cars here with dodgy MAS, but disconnecting them made no difference, but a new MAS cured the problem.
 
The MAF is the easiest thing to try, my reasoning was that they new key start corrected it for a while, and with other faults this would not happen.

Its an easy DIY and always handy to have a spare as it will need replacement at some point in time.
 
The MAF is the easiest thing to try, my reasoning was that they new key start corrected it for a while, and with other faults this would not happen.

Its an easy DIY and always handy to have a spare as it will need replacement at some point in time.

I agree with you, i've changed the MAS on every CDI i've had so far. The only problem is when you disconnect the MAS to try and eliminate it, it will bring up a fault code. Just makes life harder when diagnosing it further down the line.
 
I agree with you, i've changed the MAS on every CDI i've had so far. The only problem is when you disconnect the MAS to try and eliminate it, it will bring up a fault code. Just makes life harder when diagnosing it further down the line.

OK I am more used to petrol and disconnecting it does not put a fault code on very often.

While talking about MAF sensors , what a rip off they are,, no more than £3 to make at the most
 
The MAF is the easiest thing to try, my reasoning was that they new key start corrected it for a while, and with other faults this would not happen.

Its an easy DIY and always handy to have a spare as it will need replacement at some point in time.

Thanks everyone for the speedy responses, looks like the MAS filter is a safe bet. My local Merc Specialist has quoted about £180-£260 (depending on my chassis number apparently) for a new one. I trust this is about right?

They say they'll fit it for free as well. So think its only fair to give them a plug. Its a place called 'The Garage' in Whitworth who have serviced my car since I bought it. They always come across as friendly and genuine people. Who could ask for more.

Thank you again for all your advice
 
Bosch charge £147 or there about and it takes 15 mins max

Ah right, well that's a bit cheaper, maybe I should give it a go then.

Can you recommend where to buy one? Or shall I just pop to Halfords?
 
OK I am more used to petrol and disconnecting it does not put a fault code on very often.

While talking about MAF sensors , what a rip off they are,, no more than £3 to make at the most

Can I have half a dozen then? I'll send you a cheque for £18 plus P&P if you let me know where to send it.
 
Ah right, well that's a bit cheaper, maybe I should give it a go then.

Can you recommend where to buy one? Or shall I just pop to Halfords?

They are very easy to change, I don't know that Halfords will be able to help with this item though.
 
Ah right, well that's a bit cheaper, maybe I should give it a go then.

Can you recommend where to buy one? Or shall I just pop to Halfords?

Not from Halfords. It depends on the make if Bosch or Piere

It will have the makes name and part number on it. Bosch service centers for the Bosch,,If you look in your yellow pages under Motor factors they will stock them at trade price. These are the people who supply all the local garages, including where you were going to go.

We have all seen these little vans flying around with "Car parts" on the sides and rear, usually driven by a dishy female, they are the one to use.
 
If it's a pierburg MAF then it's going to cost about £50, a Bosch one substantially more.

Before replacing it see if you can measure the output from Pin 5 with respect to Gnd. It should be approx 2v at idle and upto 4.5v at full revs.

I suspect the EGR valve or maybe the resonance flaps, but EGR is No1 bet.
 
£60 from Eurocarparts. Its a Pierburg one, the same as original. £150+ is taking the mick, i would find another garage. :crazy:

Go to www.eurocarparts.com and you can buy it online.
 
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If it's a pierburg MAF then it's going to cost about £50, a Bosch one substantially more.

Before replacing it see if you can measure the output from Pin 5 with respect to Gnd. It should be approx 2v at idle and upto 4.5v at full revs.

I suspect the EGR valve or maybe the resonance flaps, but EGR is No1 bet.

What does one do on these post,, you can read it several times, think about the EGR,, then read it does when pulling and that is the time when the EGR is closed, and it resets on the key. My mind at this point goes over to the MAF,, its the cheapest and easiest thing to change, and is known to do this.

No one particually me, wants anyone to buy what they do not need. One has to start somewhere. Its very hard sometimes.

My own V70 will not run with the faulty MAF connected up and drives perfectly with out it
 
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Why don’t start from trouble codes reading ?
Is it so expensive there ?

If there are “too much codes”, just empty it, and read again after few days.

Like KLP 92 already says, mostly there is information availably.
And if not, that is a clue too.

If reboot solves the problem, that points to some kind of “air-troubles”

EGR causes mostly permanent limp mode.
 
A point worth noting about Eurocarparts. Oil filter for a C240 over the counter. £8.89 plus vat. Buy on line, £4.00 plus vat. Suppose same suffix to all oil filters ?

Bizarre set up.
 
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Quick update and completely unrelated... Left the local sandwich shop at lunchtime, reversed the car to find I had NO brakes! This is not my week :-( One of the brake fluid lines has snapped on one of the 90 degree corner pieces....

Gets me to thinking 'Who have I annoyed recently???' :O
 

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