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Discussion Starter #1 (Edited)
Hello

Few days ago my car lost power while I was driving to work and eventually the engine stopped. It would start back up again straight away but stop after 20 to 40 seconds ish.

No fault codes were stored and the way the engine would shudder to a stop got me thinking it was mechanical type fault.

I pulled the vacuum line off the EGR valve and sure enough, no more shuddering to a stop. If I waited until the engine was about to stall and then pulled off the vacuum line, the engine would recover back to idle speed.

I T'ed a vacuum gauge into the hose to the EGR valve and this shows the vacuum building from startup until it is enough to open the EGR valve and the engine then stalls.

Should the EGR be opening at idle ?

My current thinking is that the solenoid valve that controls the vacuum to the EGR is sticking or leaking and allowing the vacuum to build up at the EGR valve.

Slight complication is that with the vacuum hose to the EGR disconnected, the car can be driven but loses power at high RPM. The boost reads 22 psi from about 2000 rpm until just over 3200 rpm when it drops away to about 6 psi.
The boost drop explains the power drop and it seems to happen at the engine speed where the large turbo should be taking over.
I can't think how this could be related to the EGR behaviour ?




This shows how I connected the vacuum gauge.


https://youtu.be/O0eXkwCrGeM


This video hopefully shows what is happening. When you see my hand I am pressing a button to release the vacuum to show how the idle recovers.


Any ideas would be gratefully received
 

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I had a problem with very low power at low revs, and this could be immediately resolved by pulling off the EGR vacuum hose and simply plugging it. Then the car would drive fine, albeit with the Emissions warning lamp coming on after a short while. The fix was to replace the EGR pressure converter, which is responsible for actually controlling the vacuum feed to the EGR valve. My car is an 2006 (pre-LCI) E61 530d by the way. There were no fault codes for my issue either. My local indy did the work, and they also replaced a couple of vacuum hoses while they were at it.

If you're problems are EGR related then it may be worth replacing the pressure converter?
 

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i had the same issue running warm at low rpm in barcelona it kept going wobbly and tryng to cut out
i have bunged the vac hose and run with egr closed permanently and no issues and no hi power issue either
as mentioned above the pierburg vac valves may be partly failed ( buzzing) or stick open in which case your engine will be drowning in its own own exhaust
also bad for for consumption+ 15 pct and clogging up the dpf see my earlier posting about this
cheers
paul
 

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Discussion Starter #4
Thanks for the replies.

I've decided to replace the solenoid valve, or pressure converter as BMW call it and see what happens.

Got it today and got the inlet manifold off so should have it fitted tomorrow.

Waited 40 minutes in the dealers to be served by the parts guy, got home and discovered they'd given me the valve that operates the swirl flaps.

Called them and they had the correct one in stock but had to go give them the £30 valve back and an extra £50 as the correct part is £80.
 

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Hope that fixes your problem. It's probably worth checking the condition of the vacuum hoses while they're accessible, if you haven't already, too.
 

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Discussion Starter #7
Thanks for the replies.

Just to update this thread, I fitted a new EGR pressure converter and that solved the engine cutting out problem although I still have the high RPM power/boost issue which I'm now treating as a separate problem.

To be sure, and to help anyone trying to diagnose a problem like this, I put the vacuum gauge back on the EGR valve to see what the readings were with a new pressure converter.
At tickover there was no vacuum what so ever and the needle on the gauge didn't move off zero.
 
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