W210 320 CDI Lack of power

[Robster_1981]

My Luxo Barge is poorly
The other night on the way home from work, it went in to limp mode (no power and revs limited to 3000rpm) I pulled over and checked everything, but nothing obvious. I unplugged the MAF and EGR which made no difference, plugged them back in and re-started the car and it seemed to run ok, but was lacking a bit of oomph.

Since then the power has almost gone, and I can hear the turbo whistling quite loud under load. Strangely, after about 3750 rpm, the boost starts to come in and power is close to normal

I'm suspecting a split pipe somewhere, but I can't see them all very well without taking the lower cover off, which I won't get chance to do until Sunday.

There are no warning lights on the dash, the car starts and runs really smooth apart from the lack of power.

 

[ted320]

My Luxo Barge is poorly
The other night on the way home from work, it went in to limp mode (no power and revs limited to 3000rpm) I pulled over and checked everything, but nothing obvious. I unplugged the MAF and EGR which made no difference, plugged them back in and re-started the car and it seemed to run ok, but was lacking a bit of oomph.

Since then the power has almost gone, and I can hear the turbo whistling quite loud under load. Strangely, after about 3750 rpm, the boost starts to come in and power is close to normal

I'm suspecting a split pipe somewhere, but I can't see them all very well without taking the lower cover off, which I won't get chance to do until Sunday.

There are no warning lights on the dash, the car starts and runs really smooth apart from the lack of power.

mine did something simalar and it was the air filter to radiator surround piece of trim not fitted correctly and closing when you accellerated hard.But i expect you have checked that already.

 

[Robster_1981]

mine did something simalar and it was the air filter to radiator surround piece of trim not fitted correctly and closing when you accellerated hard.But i expect you have checked that already.

Thanks for the reply. I couldn't see anything obvious, but I'll have a closer look around there

 

[ted320]

My Luxo Barge is poorly
The other night on the way home from work, it went in to limp mode (no power and revs limited to 3000rpm) I pulled over and checked everything, but nothing obvious. I unplugged the MAF and EGR which made no difference, plugged them back in and re-started the car and it seemed to run ok, but was lacking a bit of oomph.

Since then the power has almost gone, and I can hear the turbo whistling quite loud under load. Strangely, after about 3750 rpm, the boost starts to come in and power is close to normal

I'm suspecting a split pipe somewhere, but I can't see them all very well without taking the lower cover off, which I won't get chance to do until Sunday.

There are no warning lights on the dash, the car starts and runs really smooth apart from the lack of power.

i have thensame car and has done the same thing twice now,both times turned out to be the pipe going from radiator surround to the air filter,the main air filter inlet,was not connected to the radiator surround and was closing when you accelarate.Maybe you have checked this already tho.

 

[Robster_1981]

I've had another poke around and can't find any evidence of a split pipe, but there is a fair amount of oil underneath the actuator on the turbo. The pivot arm seems to move freely, but the fact that the car seems to come on boost high up in the rev range leads me to think it could be that playing silly beggars!

If I got the car plugged in on a Star system, would it diagnose problems like this?

P.s. I can't replicate any noises when the car is not under load which is frustrating

 

[jaymanek]

Have you checked for a split intercooler hose?

It does sound like a boost leak somewhere.

 

[Robster_1981]

I've checked all the intercooler hoses and can't see any splits or cracks. When the turbo starts to spool up, I get the same noise I get when I release the throttle. This leads me to think that the wastegate is stuck open??

How would I know if that is the case?

 

[i777]

My 320 cdi CLS did something a little similar a while back. It hesitated when overtaking once and then went into a limp mode setting. I stopped an re started the car and it was fine. I mentioned it to the dealer when it was in for a minor elec. window fix and they said they'd check it out. They found a fault code and said they would fit a new turbo (fortunately I have a Tier 1 warrranty). As a precaution/bonus! they also fitted a new inlet manifold. Now I'm not sure what the actual problem was, or whether they just threw expensive new parts at it because it's under warranty (and MB pays) but it certainly hasn't done it since and it feels even more responsive than before.

 

[BlackC55]

Why don't you get someone to rev your car while you listen at the front end. Check the ends of the intercooler as that's whet they tend to leak.

 

[Robster_1981]

Why don't you get someone to rev your car while you listen at the front end. Check the ends of the intercooler as that's whet they tend to leak.

Not tried that yet, but I did notice a load of silicone around one end of the intercooler, although there wasn't much sign of it leaking. I'm getting it plugged in at an Indy tomorrow just to rule out some sensor or other

 

[Robster_1981]

I've had the car in the garage and plugged in. It brought up a few fault codes, but they were all related to open circuits from where I unplugged the MAF and EGR. They diagnosed a vacuum leak using a smoke tester, and did a repair on the hose. I got the car back the same day and all was fine

2 days later, the same problem creeps back and now the car keeps dropping into limp mode and I can hear a whistle on acceleration again. To me, it sounds like the wastegate is staying open.

From under the bonnet, the wastegate actuator arm is in the 'up' position and free moving. If I push it down with a screwdriver then rev the engine, I can feel it push up, but not with much force, and to me it doesn't seem to be operating properly.

So it seems either the vacuum leak has returned, or the wastegate is faulty?? I am confident that all the pipes are leak free, but what about the transducers...is there any way of diagnosing them DIY style?

 

[mersum1es]

I've had the car in the garage and plugged in. It brought up a few fault codes, but they were all related to open circuits from where I unplugged the MAF and EGR. They diagnosed a vacuum leak using a smoke tester, and did a repair on the hose. I got the car back the same day and all was fine

2 days later, the same problem creeps back and now the car keeps dropping into limp mode and I can hear a whistle on acceleration again. To me, it sounds like the wastegate is staying open.

From under the bonnet, the wastegate actuator arm is in the 'up' position and free moving. If I push it down with a screwdriver then rev the engine, I can feel it push up, but not with much force, and to me it doesn't seem to be operating properly.

So it seems either the vacuum leak has returned, or the wastegate is faulty?? I am confident that all the pipes are leak free, but what about the transducers...is there any way of diagnosing them DIY style?

No wastegate, they are VNT...

Similar issue(?):
E320 Cdi year 2000 Limp Home mode - Mercedes-Benz Owners' Forums

 

[Robster_1981]

Thanks for that info, I had a quick read up on VNT and it seems that they can get clogged up, but I can't see it being that as the car has been working on and off.

I did look at the video's regarding the actuator movement, and mine doesn't move anywhere near that much! It's as though it's almost at the top of it's travel before anything happens, if that makes sense?

Mine symptoms are pretty much the same as that thread. I might try checking the resistance values on the transducers. Have you any idea what the values should be?

 

[BlackC55]

I'm pretty sure they do have a wastegate.

I would looking at the transducer(s) certainly. And see of you can find where that whistle is coming from. This is likely to be a boost leak.

 

[Robster_1981]

Fixed it

I found that there was little or no vacuum anywhere on the system, but as the brakes work fine, I assumed the pump was ok. I then noticed that the turbo and EGR lines were fed from the brake servo pipe. After a bit of investigation, by blowing into the lines and blocking one end, there didn't seem to be a leak.

It was only a hunch, but I took out the servo pipe and sucked on the end (I would advise getting the Missus to do this ) and I got a load of crud in my mouth!! Hey presto, the car now runs like a dream!!!

Thanks for all the advice

 

[august.sun]

picture and location of the responsible pipe

Hi robsuter pleased to hear that you have solved the problem can you kindly upload a picture of the culprit pipe here or send it to me on [email protected] as I am having exactly the same problems with my e320 cdi, I am now fed up of mechanics telling different stories to me.
many thanks

 

[chriss428]

+1 on the pipe pic please going to go check all the above mentioned now

 

[Danielprks]

Fixed it

I found that there was little or no vacuum anywhere on the system, but as the brakes work fine, I assumed the pump was ok. I then noticed that the turbo and EGR lines were fed from the brake servo pipe. After a bit of investigation, by blowing into the lines and blocking one end, there didn't seem to be a leak.

It was only a hunch, but I took out the servo pipe and sucked on the end (I would advise getting the Missus to do this ) and I got a load of crud in my mouth!! Hey presto, the car now runs like a dream!!!

Thanks for all the advice

What pipe was blocked mate? Dont want to go round sucking on every vacuum pipe on my merc as my neighbours already think im strange enough!

 

[BrabusD6*]

Fixed it

I found that there was little or no vacuum anywhere on the system, but as the brakes work fine, I assumed the pump was ok. I then noticed that the turbo and EGR lines were fed from the brake servo pipe. After a bit of investigation, by blowing into the lines and blocking one end, there didn't seem to be a leak.

It was only a hunch, but I took out the servo pipe and sucked on the end (I would advise getting the Missus to do this ) and I got a load of crud in my mouth!! Hey presto, the car now runs like a dream!!!

Thanks for all the advice

Hi do you have any more info on this? what pipe is it that was clogged up?
Cheers

 

[bob6600]

What pipe was blocked mate? Dont want to go round sucking on every vacuum pipe on my merc as my neighbours already think im strange enough!

Hi do you have any more info on this? what pipe is it that was clogged up?
Cheers

If you look near the brake servo you will see the vac pipes (plastic) that feed the EGR and Turbo, joined with a T-piece IIRC. You can disconnect these and blow down them to ensure they are not blocked