Can I test the EGR valve on 03 ML 270cdi?

[Stuie]

Hi
Still having problems with intermittant revving and kickdown problems. Can i test the egr valve? If so where is it? And will these problems show up on a snap on diagnostic, as i might be able to lay my hands on one?

This is still driving me nuts.

Thanks guys.

 

[BlackC55]

Have you looked at the inlet port shut off yet?

 

[Stuie]

I don't know where that is either!!

 

[BlackC55]

Under the inlet manifold attached to it.

is it still attached to the motor that moves the flaps?

 

[Stuie]

Ive noticed there is a smaller pipe below the MAF that seems to be leaking oil where it joins the pipe to the air filter box. The oil is all over a plug that goes into the smaller pipe if that makes any sense !!!!

 

[KLP 92]

Not really.

If you're not technically minded then CDI engines aren't that easy to diagnose at home. As you've been told in your previous posts it could be a whole list of problems.

Until you plug the car on diagnostics and have a competent mechanic look at it you'll be putting up posts here for a long time and have various answers been thrown back at you:

http://mbclub.co.uk/forums/showthread.php?t=50465

http://mbclub.co.uk/forums/showthread.php?t=50505

Bite the bullet and have the car checked properly.

As i stated to you first, check the basics. Air intake/intercooler for leaks, inlet port shut off motors and then the EGR valve.

It could still be a MAS issue, disconnecting it or cleaning it aren't an accurate way to test.

 

[tuikku]

.
29=servomotor.
47=mixer housing.
77=exhaust gas recirculation line.
104=exhaust gas cooler.

 

[colinhelen]

Help - new to forum and can't see where to add a new topic, but mine is similar. I just spend £414 getting my EGR valve replaced on my 2002 E320 cdi. The garage said that the system says there is a loss in vacuum in the EGR system - (AFTER replacing the valve) but they told me the power loss was at the top end and tiny. In real terms, I have lost the kick-down. Pushing the throttle all the way to the floor and onto the switch does nothing, and putting a heavy right foot down used to make the engine rev in lower gears as it accellerated but now it's all very slow. What have they done? Also, there is a solenoid that sits next to the nearside wing in the engine bay, and they said it may or may not work (worked bloody well yesterday) and there's a tiny (air?) filter on a rubber pipe just laying against the bodywork coming out of the bottom of it. It seems totally random and out of place for a Merc and looks like it should be inside something, rather than just laying on top of the inner wing. And finally, there's a tiny grey tube that goes into the top of the solenoid and if I blow on it I can build up a bit of pressure, but sucking on it there is definitely air coming thru slowly. Is this right? Said garage has had £600 this week so I'm keen to be able to go in and sort it. Thanks in advance.

If anyone has any ideas of what to look at / for, i'd be really grateful.

 

[Dieselman]

The little filter is correct, it's just a vacuum bleed off.
I see it's a W210. hold on.

If the vacuum system is leaking the EGR valve and turbo wastegate won't be working properly, hense the lost power.
http://www.detali.ru/cat/oem_mb2.as...GA=722.626&CT=M&cat=65C&SID=14&SGR=170&SGN=03
The solenoid valves control vacuum for the EGR valve and turbo wastegate.

It's worth checking the intake flap linkage is properly connected under the manifold as that could cause air starvation, but I think it's the vacuum leak causing loss of boost.

http://www.detali.ru/cat/oem_mb2.as...GA=722.626&CT=M&cat=65C&SID=14&SGR=030&SGN=01

If you're struggling ditch your garage and take the car to BlackC55 on this forum. He is in Horndean.

.

 

[colinhelen]

thanks for that - I think I may have spoken to Blackc55 before - he was very knowledgable. I went to the garage that has worked well on my previous cars and also the company fleet, but if they don't sort it tomorrow I know who to call. A shame I spent the £400 first tho. (My own fault)

 

[Dieselman]

What's probably happening is that somehow they have caused a vacuum leak which is stopping the EGR valve working. This is detected and causes the turbo to drop the turbo.

Remove the pipe leading from the valve to the EGR valve and suck on it, it should have solid vacuum. The solenoid valve will leak vacuum so as to release the EGR valve when required.

Try the same trick to the turbo actuator as well, but you should be able to see this operting the link rod when idleing.

Surely the garage are going to fix this.

 

[tuikku]

.
It is possible to test, if EGR-valve shuts down correctly.
You need laptop and program + obd-wire, with which you can read car sensors information.

Here is situation in well-shaped, stock ML270cdi.
Full acceleration.

Red = boost pressure
Green = rpm
Yellow = intake air temp, it was quite warm day.
Blue = air mass

[FONT=&quot]If MAF – sensor brakes down, or EGR don’t shut down properly, air mass in full acceleration is less, than ~1500mg[/FONT]

 

[Dieselman]

I can't see any influence of the EGR valve on those readings as they were WOT boost readings.
Where was the AIT being measured, pre or post boost. If post boost the rapid temperature rise is a result of air being compressed, if before it's due to not enough cooling air being forced into the engine bay when producing power.

Your theory and readings are correct but would be influenced by the condition of the MAF sensor as well, so can't be relied upon as a true result.

A simpler method for a home mechanic is to meter pin5 of the MAF sensor and disconnect the vacuum line going to the EGR valve. This should force the MAF reading to increase as a result of more fresh air being drawn in.

Disconnecting the EGR valve will force the ECU into limp home mode, dropping the turbo, which is what I suspect is happening.

 

[tuikku]

I can't see any influence of the EGR valve on those readings as they were WOT boost readings...

In full acceleration, EGR should be closed.
So, MAF shows the real amount of air going into engine.

If intake air mass is under ~1500mg level.
And engine reach the max boost level.
MAF could be broken, or EGR – not closed.
There could be other problems, too, but this is one way to measure, if EGR is ok.

In fact, there is not any recirculation-map in program.
There is only maps to “fresh” air.
And MAF is measuring it.
So, when program adjust the level of recirculation, it actually adjusts the amount of intake fresh air.
“MAF adjust EGR”.

In ML270cdi, air intake temperature – sensor is in cooler, engine side.
When temperature rises over ~50C level, program start to decrease power.

These are facts.

I am not going to start argue with you, my English is not enough good.
- And I don’t want to.

You can believe, or not.
It is very same to me.
Or maybe I understand something wrong.
But your behaving surprises me.
If you don’t want me to write here, just tell, it is ok.

 

[Dieselman]

In full acceleration, EGR should be closed.
So, MAF shows the real amount of air going into engine.


I am not going to start argue with you, my English is not enough good.
- And I don’t want to.

You can believe, or not.

No argument and your description is correct, but the WOT throttle readings won't help the o-p as his EGR is stuck closed due to leaking vacuum.

As you say the EGR will be closed at WOT and the charts show no change of state of EGR operation at WOT anyway, as there isn't any.
If the EGR valve was stuck open then there would be a loss of inducted air shown by the MAF reading, but a faulty MAF would give similar results so introduces a variable into the checking procedure.

A better check of EGR operation is at idle where the EGR valve will be wide open so a change of state can be measured without any other variable such as faulty MAF. The MAF may read incorrectly but it will still show a change of state with the EGR valve open and then closed.

Is that ok.?

 

[tuikku]

.
Yes, you are partly right, at the beginning EGR is totally open.
After couple of minutes idling, program turns EGR-ventile “closed”.
You can actually hear, when.
Sound of engine changes.

 

[Dieselman]

We experienced this when metering a members car a few weeks ago. The MAF output at idle went from ~1.55v to ~1.98v due to the operation of the EGR valve.

You can test and hear this change by sucking on the EGR vacuum pipe on a car with vacuum operated EGR.

 

[colinhelen]

Well - After your advice I got under the bonnet and tried all of the connections. With engine running, there was vacuum and no apparent leaks. But the solenoid next to EGR was buzzing. It sounded like the air filter hanging off it was making a noise like a zither. I took the air filter off and gave it a blow off and tapped it a few times and did the same to the solenoid. THen, perversely, I put my finger over the end that the tube for the air filter went into. The engine coughed and a little cloud of dust/smoke puffed up from somewhere near the turbo. OMG!!!!! What have I done??? etc etc was the thought. Anyway, I realised engine was a bit quiter and revved ok. Took it out and WOW - I now realise how much power the car has. A littel tweak on the throttle and sh'ell drop down and roar off up the road. Put my foot down and after just a few seconds went over 100. The car has NEVER driven like that. Do you think there was a blocked tude or something, hence the little puff of dust / smoke?

 

[Dieselman]

That sounds like the modulator valve was stuck half open and leaking vacuum off. That will cause the turbo wastegate to drop so reducing power significantly.

The puff is probably the wastegate slamming shut as vacuum was applied suddenly.

Why did the car have a new EGR valve? It sounds like the problem may be the modulator, not the valve.

See how it goes, if necessary fit a new modulator.