E270cdi turbo overboosting and going into limp mode

mafya

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Hi there peeps, well i'm back again with another problem. As stated in my previous thread i have replaced the cylinder head, injectors and new turbo unit but not the turbo actuator. The car runs fine but when i go 3000 rpm the car goes into limp mode but after a restart all is fine.
No engine management light comes on. Had it on a launch diagnostic unit and the the stored code states=

Check component stored b5/1 (charge pressure sensor). Charge pressure is too high.

The turbo was changed because when the head was being fitted the mechanic noticed that the turbo spindle had excess play and didn't want to refit this turbo incase it failed and damaged the engine. The replacement turbo is a recon unit.
Had a guy who rebuilds turbos have a look at it today, he refitted the turbo and says the actuator arm has excess play in it and has shortened it a bit which has made a minor difference.
The car was running fine before having the head and turbo changed. The cracked head problem is sorted but this turbo problem has now popped up.
I'm in the doghouse with the mrs as i have spent over 2500 on the car and it is still not running right and i promised her we would be having plenty of day trips out.
Could it be that the turbo actuator needs changing aswell?

Billy
 

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I think this...... If its not an ecu fault the only way you can be getting excessive boost pressure is if the flow through the exhaust isn't correct. There is no other way on a cdi. How long you had the car? I came across this problem once. A guy had bought a 220cdi and kept getting a similar fault. Turned out somebody had cut the cats out of it and rewelded the exhaust. This will throw the boost values out. just a thought fella!!!
 
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Alf maybe onto something here. If the boost pressure is too high in the charge pressure system it means there is a flow restriction somewhere. If the KAT is broken/blocked then this will impact on the charge pressure system. Also check the turbo vacuum transducer, but I am pretty sure that brings up a "charge pressure too low" fault code.
 

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Im pretty sure im right Steve. When it happened to me i was head scratching.
 
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mafya

mafya

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I think this...... If its not an ecu fault the only way you can be getting excessive boost pressure is if the flow through the exhaust isn't correct. There is no other way on a cdi. How long you had the car? I came across this problem once. A guy had bought a 220cdi and kept getting a similar fault. Turned out somebody had cut the cats out of it and rewelded the exhaust. This will throw the boost values out. just a thought fella!!!


I have had the car about 6mths now, it was running fine apart from loosing water thru a cracked head. This problem has only appeared after the turbo was changed at the same time as a new head.
Could it be that the egr valve needs a clean?
I will get the cats looked at though.

Billy
 
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mafya

mafya

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Alf maybe onto something here. If the boost pressure is too high in the charge pressure system it means there is a flow restriction somewhere. If the KAT is broken/blocked then this will impact on the charge pressure system. Also check the turbo vacuum transducer, but I am pretty sure that brings up a "charge pressure too low" fault code.


Where is the turbo vacuum transducer located?


Billy
 

Riverstick

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Leave the cats alone!....if they are removed and the engine ran fine beforehand...leave them off......unless you want to loose about 10mpg and about 30 bhp.

The egr system only operates on idle and over run....and I would imagine whoever fitted the cylinder head would have cleaned out same.

If your turbo is over boosting,you have a leak in your charge circuit...check your intercooler/trunking/connectors.... A handy way to DIY this is to prop and old mattress against a wall....gently drive your car against it....open bonnet fully.....place transmission in drive....gently press accelerator and get someone to observe your turbo/intercooler/trunking system....the leak should be immediately audibly obvious as your turbo build boost pressure and its leak manifests itself under load. The plastic trunking pipes in particular are prone to splitting along the seams and only really manifest themselves under pressure.

Oh...and make your wall is strong enough to withstand the force of the car gently pushing it....because if it collapses and your car ends up revving its way into your sitting room...your wife will be seriously pee'd off with you!
 

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I think you ll have an electronic actuator on the turbo on your 211. No vac transducer.
 
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mafya

mafya

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update

i think i know what the problem may be. My turbo is the one with the electronic actuator and i came across information that at manufacture, the individual turbo has (I think) 20 vane-position settings programmed into the actuator, corresponding to 20 levels of increase in boost across the turbo - i.e. specific to THAT turbo. This calibration machine is NOT available to the field and so a new actuator (if it was available) can't be "tuned" to the old turbo.......a scrapyard actuator is therefore likely to result in over or under boost problems..
Mine is a recon turbo that didn't come with an electronic actuator so the turbo is a recon one but the actuator is my old one that is programmed specificly to my old turbo.
I'm going to get in touch with the company that supplied the turbo and explain all this and ask why they are selling recon turbo's without the actuator that is calibrated specific to the turbo and demand my money back.
I'm 99% certain i'm right as before the car ran fine without any overboost problems.
The lesson here is don't buy a second hand or recon turbo without the electronic actuator that is calibrated to that turbo.

Billy
 

Riverstick

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i think i know what the problem may be. My turbo is the one with the electronic actuator and i came across information that at manufacture, the individual turbo has (I think) 20 vane-position settings programmed into the actuator, corresponding to 20 levels of increase in boost across the turbo - i.e. specific to THAT turbo. This calibration machine is NOT available to the field and so a new actuator (if it was available) can't be "tuned" to the old turbo.......a scrapyard actuator is therefore likely to result in over or under boost problems..
Mine is a recon turbo that didn't come with an electronic actuator so the turbo is a recon one but the actuator is my old one that is programmed specificly to my old turbo.
I'm going to get in touch with the company that supplied the turbo and explain all this and ask why they are selling recon turbo's without the actuator that is calibrated specific to the turbo and demand my money back.
I'm 99% certain i'm right as before the car ran fine without any overboost problems.
The lesson here is don't buy a second hand or recon turbo without the electronic actuator that is calibrated to that turbo.

Billy

Sounds like a plan Billy....Garrett recently told us at a technical seminar you cannot purchase/replace the electronic actuator separately as each unit is calibrated to each specific turbo.....could be the root of your problem perhaps....I was diagnosing 'overspeeding' in my previous post above....Keep us posted on any progress...
 

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Good luck with the diagnosis Billy. I ve never been supplied a recon turbo without the electronic actuator. Strange! And just for future reference, if the cats had been removed {although they obviously haven't}. The engine would keep going into limp and would give the same fault code you are getting.
 
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mafya

mafya

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Have you checked the top hose for splits?


All the hoses are fine, the actuator arm needs adjusting to suit the turbo. It's going back on the 2nd August and the mechanic says if they can't sort then it will be a case of a refund of my money from the turbo company.
Will update as i know more.


Billy
 
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mafya

mafya

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Update

Hi there peeps, just to let you know the turbo problem has been sorted and the car is running spot on. The mechanic had to "turn the turbo in the housing to turn the boost down", his words not mine.
So just to recap, car had a new head due to old one being cracked and causing the car to hydrolock and burn out 3 starter motors, all injectors reconditioned, new rocker cover due to old one cracking while removing seized injectors and a reconditioned turbo.
Total cost was just under £2900 but well worth it as car should run trouble free (fingers crossed) for a good while.
This is my first mercedes and there was a point when i was regreting buying it.
This forum has been a good help as well so will visit weekly.

http://www.mbclub.co.uk/forums/attachment.php?attachmentid=25063&stc=1&d=1312408730

http://www.mbclub.co.uk/forums/attachment.php?attachmentid=25064&stc=1&d=1312408847

Attached are a couple of pics of the car, it has been de badged now.

Billy
 

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