E320CDI strange gear changes

[joeysnowey]

Hi all, my 2001 E320CDI estate auto is not managing its gears correctly. I get stuck in a low gear when it should change up and relax the revs. It is costing me more on fuel as a result but I am more concerned with what might be the problem
I am about to spend a few hundred quid on it for a service etcetera, but want to find out what this problem might be beforehand, in case of the worst

At 55 mph cruising it should go into top gear, always used to, but it doesn't. I have to get over 60-65 quite often, just to get into top gear. Its a pain. Also sometimes when slowing for junctions or roundabouts it drops too early causing a slight jolt. Nothing too dramatic, but enough to ruin the comfortable motoring I am used to in her.

Any ideas any of you MB egg spurts?

 

[joecash]

needs to go on STAR

 

[joeysnowey]

I dont understand what you mean?

 

[230K]

He means that the car needs to be plugged in to the Mercedes Benz Diagnostic System STAR.

Once plugged in its should show up the problem.

Changing parts on speculation of the problem could be wasting your money.

Thanks,

230k

 

[Dieselman]

Probably a failed MAF sensor.

 

[joeysnowey]

AAAH, thanks so much guys.

I had to replace the MAF sensor on my old E320 CDI, thanks to this forum for pointing it out then, and possibly again!

Could it really be something that simple? I had visions of it probably being a new gearbox, i.e. a write off

Will diagnostics show up a faulty MAF sensor, I thought sometimes it doesn't show up on there?

 

[renault12ts]

It could indeed be that simple...but a STAR diagnosis will confirm it.

 

[Dieselman]

A MAF is a s cheap as a diagnosis and can be tested with a multimeter.

 

[joeysnowey]

thanks very much. I have a multi meter but wouldn't have a clue how to test the mAF, let alone find it these days!
I will get the car tested asap. thanks again

 

[Shacks]

I know a little bit about cars and I know that a little bit of knowledge can be a dangerous thing but I am intrigued as to how the MAF could be responsible for the gearbox not changing up. Does anybody know why this is or is it just past experience? Please don't think I'm questioning your diagnostics, I'm just curious. Thanks Steve

 

[Dieselman]

A low reading from the MAF reduces the quantity of injected fuel, so reduces torque.
The gearbox will hold a lower gear due to the reduced available torque.

 

[joeysnowey]

Jesus there are some clever minds on here!!!!!

 

[Shacks]

Thanks for the reply Dieselman, I would never have associated the MAF to the gearbox.

 

[joeysnowey]

Hi all, well I changed the MAF sensor and it made no difference at all. My gears are a pain in the bum. Everywhere I go I have to hold the stick to the right to try to keep it changing up, but even doing that doesn't always work and it will usually drive everywhere one gear too low for the speed, so costing more on fuel. I have a local mechanic who has some daig equipment, not sure if its official Merc Star stuff though. Would that matter? He said he can plug it in and get fault reports, but not as many as "a merc dealer would get". Any advice on whether he is worth visiting or not?
Thanks

 

[ricardo62]

Jesus there are some clever minds on here!!!!!

that dieselman is a sage and fountain of knowledge

 

[ricardo62]

Hi all, well I changed the MAF sensor and it made no difference at all. My gears are a pain in the bum. Everywhere I go I have to hold the stick to the right to try to keep it changing up, but even doing that doesn't always work and it will usually drive everywhere one gear too low for the speed, so costing more on fuel. I have a local mechanic who has some daig equipment, not sure if its official Merc Star stuff though. Would that matter? He said he can plug it in and get fault reports, but not as many as "a merc dealer would get". Any advice on whether he is worth visiting or not?
Thanks

my local garage uses a snap on reader and gets readings and clears faults for me only costs me a tenner

 

[joeysnowey]

I was driving my E320CDI the other night on a very long trip with 4 kids on board. For a while I heard a very faint whining sound, it went louder with the revs and sounded almost like a worn plastic washer sound, a whirring sound. Anyway after a good few hours, it suddenly revved too far between up changes (its auto of course) and then it seemed to get stuck in neutral. After a good while of stopping and freewheeling, I turned it off and on, and it seemed ok after that at least for a while, then did it again.
Is my gearbox fubar?! Anyone had a similar experience?
Any advice greatly appreciated. Thanks