ML270 slow acceleration

[psmart]

Hi all,

Has anybody had experience on an ML270 auto (or other 270cdi vehicles) where you press the accelerator (not kick-down) and it takes several seconds before it starts moving, power boost is very slow, almost like the Turbo is not winding up quickly.

My car went in to Merc last week for 5 new glow plugs, 2 of which had to be drilled out, and after it being returned, the glow plug light still comes on and stays on as well as the above problem. Before I start stripping the engine to verify the work and confront the dealer, I was looking for advise on the acceleration problem.

Many thanks,

Phil.

 

[jberks]

Is it different to how it was or just a general comment?. How is it once rolling?
There are faults that could explain your problem but I find with all CDI's, including my E270 there is some turbo lag, but then my old v6 petrol was a bit lacklustre under 3,000 rpm so I adapted and tend to press the throttle a second or so before i need it to compensate. Its all down to revs really.
Kick them over the glow plug issue though.

 

[psmart]

Basically, before going in for the glow plugs, you would be at the lights, pulling out into a junction or generally just wanting to accelerate, I'd press the accelerator to the floor or half way and the car would lurch forward with gusto. Sometimes if you caught the turbo off song, it would have a brief 'pause' then lurch forward with gusto.
After returning from the glow plug change, same scenarios, the car would crawl forward, gradually building up pace until after about 3-4 seconds, when it would go forward with Gusto.
Now the crunch comes when you hit kickdown, from a standing start or when your crawling along at say 5-10mph. You would get almost original acceleration.
I've owned a Montego Turbo and Sierra Cosworth before, and with the Montego, when the air pipe disconnected on the air output (pressure side), you had the acceleration and performance of something akin to a 2CV. On the Sierra, when the waste gate was sticking, you had something similar because all the boost gases were being vented away from the impeller.
Hence I think its something to do with air mass or boost pressure sensors, which Merc could have disconnected/damaged when they replaced the glow plugs.
As the engine is completely electronic, it could be something completely un-related to the Turbo!
This ML-270 has been the model of reliability since new (5 years ago) and has always been serviced by Merc-Care. First venture to a Merc-Dealer and look what happens!!

 

[jberks]

Merc-Care? - I assume you're around Leeds. Thats where mine is off to in a couple of weeks.

As glow plugs don't affect performance or normal running, and it was fine before, as you say, they've clearly done something wrong. What is anyones guess, from busting a pipe somewhere to not plugging something back in properly. Back it goes I would suggest.

Derwent was it?. I've had them fail to do stuff on the job sheet and completely ignore instructions, but to date, they've never actually broken my car!.

I'm curious though, why did you use a dealer especially with such a labour intensive job?

 

[psmart]

Merc-Care in Leeds, highly recommended (other than their labour rate doubling recently and ignorance of emails!).

I spend most of my working life in Europe and as it is, Im in Düsseldorf at the moment, home of the Merc Van factories. Therein lied my problem! A bona-fide Daimler Chrysler Ag workshop... and could they get it right???

My German isnt good enough to have a 1-on-1 heated argument about these problems, so this is why I'm interested if anybody else has had the problem/knows the solution to the slow acceleration, so I can confront the workshop armed with exact knowledge (or repair it myself and save time and agro!).

The E-Class is a nice car, I rented one last weekend in Munich (in E220cdi disguise, auto), it did 143mph on the clock!!. With troubles starting on my 5 year old ML, I've started to look at possible replacements, and the E320CDI/ML320CDI seem the logical migration. Trouble is which!!!

 

[jberks]

ah decisions decisions...

 

[psmart]

Resolution

.... got my hands dirty last night, something I havent done since my boy racer days when I rebuilt engines!!!

I reseated all the electrical connections (come summer, Ill contact clean/vaseline them as a precaution) on the engine top (ie. front and rear sensors on the common rail, air sensors (on air filter and several throughout the engine as the air intake system is long - inlet-airfilter-turbo-intercooler-´cylinder head).

End result... problem cured. Car accelerates as it should. Any one else experience this or similar problems, get your hands dirty for a couple of hours and save yourself time, aggro and cost.

 

[RUBBER_UNDIES]

Resolution

.... got my hands dirty last night, something I havent done since my boy racer days when I rebuilt engines!!!

I reseated all the electrical connections (come summer, Ill contact clean/vaseline them as a precaution) on the engine top (ie. front and rear sensors on the common rail, air sensors (on air filter and several throughout the engine as the air intake system is long - inlet-airfilter-turbo-intercooler-´cylinder head).

End result... problem cured. Car accelerates as it should. Any one else experience this or similar problems, get your hands dirty for a couple of hours and save yourself time, aggro and cost.

Just read your post.

Mine is doing the same. I'll have at pook at mine. I'm thinking turbo though.