Possible MAS issue?

[Rose Chap]

Morning all,

I've noticed over the past month or so the following occasional unusual behaviour by my car.

• Very harsh gearchange to first - usually following a high speed or high rev run. For example, pulling off a motorway onto a slip road and stopping at a roundabout, the gearchange into first is very jerky. And pulling up to a stop is occasionally accompanied by a significant lurch (presumably as the gearbox shifts into first). All of this only happens once in a while and I can't make it happen on demand.

• Economy has slightly dropped recently. I used to get about 25 mpg driving to work, and lately its been more like 21 or 22. Same road, same amount of time. Apart from the last few days no significant ambient temperature variance.

• Performance doesn't seem quite as urgent as it once was. The noise and willingness to rev is still there but the thrust seems to have lessened.

The car is about 3000 miles away from an 'A' service, it had its last service (a 'B') in early October and the gearbox oil was changed. I only ever run it on Shell V Power.

Does MAS seem to be the culprit here or do I have separate issues?

Any ideas?

Cheers,

RC

 

[DITTRICH]

Might I assume that your CLK230K is a proper 2.3l engine? My car has begun to exhibit this sort of characteristic - at 82k miles - exactly as you describe. My car goes in for service on Monday and I will report back.
Les

 

[Rose Chap]

Yes, its a 2.3, 2001 X reg, 112,000 miles now.

 

[DITTRICH]

I'm going to ask the garage to clean the MAS with some alcohol spray solution or some such thing and to read any fault codes in the ECU. I should have some sort of response on Tuesday.
Les

 

[Rose Chap]

Hi Les,

Heard anything back from your service yet? The list of things requiring some level of attention at my next service is growing infuriatingly long!

Hope your wallet escaped relatively unscathed.

All the best,

RC

 

[stats007]

It could be a number of things, MAF sensor, Lambda or O2 sensors, throttle body - they all affect fueling. If it's a high speed / rpm run maybe the throttle body is sticking open slightly and needs cleaning?

 

[PeterE320Cdi]

Hi Rose Chap & DITTRICH

Please can you let me know if you got the issues with your autoboxs resolved as mine seems to also be acting strange?

Thanks

Peter.

 

[Rose Chap]

Hi Rose Chap & DITTRICH

Please can you let me know if you got the issues with your autoboxs resolved as mine seems to also be acting strange?

Thanks

Peter.

Hi Peter,

Sorry for the much delayed response - I managed to miss your reply.

I've still got the issue. A occasional lurch when changing into and out of first gear on the autobox. The car is booked into the dealers on May 1st but I'm not exactly picking up confident vibes from the service guy that they know what to do to fix it.

What's the problem that you're having?

 

[BarryS]

Hi Andy,

See you have moved on from Wokingham to the even more expensive Henley-on-Thames.

Just had the air mass sensor replaced today in my 270CDI - if this is the same thing as a MAF then the symptom I had (in a diesel) was huge clouds of smoke coming from the exhaust when accelerating. The explanation was that the sensor measures the amount of fuel used - which sounds quite different to your problems.

Barry