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535d leak off pipe pressure

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Hi guys hoping someone can help.

 

I have a 535d LCI and recently had it remapped. Since then at a certain speed/acceleration the requested rail pressure and the actual rail pressure massively differ throwing it into limp mode. We found a hole in the leak back fuel return pipe and replaced it. Now with trying 2 different clips the pipe keeps blowing off and the car doesn't feel right. I asked my mechanic if the pressure being built up in one of the injectors is just going straight through to the return pipe and blowing it but he said the car wouldn't even run if the pressure was getting through to the return pipe. 

 

Is he wrong? Any idea what my next step for diagnosis is I don't really want to give him anymore money.

 

Cheers

 

 

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For what it costs you should buy the leak off set and replace it, then check the injector correction values. A leak off test would show if excessive pressure was an issue.

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As we are talking about LCI 535d it has piezo injectors. With piezos the leak off system is different compared to older solenoid injectors. On piezos the leak off line is constantly pressurised and leak off can't be measured the same way as with solenoid injectors.

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Tried reusing the crimp connector that was on before but no luck so changed it to a small jubilee clip and both have blown off. Ah i didn't know the leak off test would be different I tried to run it and did seem to get excessive fuel on the injector that I think is the problem but guess that doesn't mean much. I have ordered a new injector Bosch code 13537809194. So will replace the one I think and work along if its not the one.

 

The reason I think its this injector is that car was throwing a smooth running code on that cylinder I took the injector out to find only half an injector seal looks like the other half had disintegrated. It was then really difficult to get a new seal over the nozzle like it had expanded. The injector in the next cylinder was fine with the same seal.

 

To blow a hole in the side of the leak back pipe must be pressure where it shouldn't be? Hopefully will know in a few days. 

 

It isn't throwing any codes atm although I can't really do a run without having to pull over with the fuel line coming off.

 

 

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Hi there, I am having the exact same problem with my 07 335D...

An injector has been replaced, starts great etc etc but when pressure build the leak off pipe always between injector 5/6 blow off. 

 

Did you solve the issue? 

 

Thanks a lot

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On 10/05/2020 at 16:45, Jay Folkard said:

Hi there, I am having the exact same problem with my 07 335D...

An injector has been replaced, starts great etc etc but when pressure build the leak off pipe always between injector 5/6 blow off. 

 

Did you solve the issue? 

 

Thanks a lot

Did you replace with a new OE leak off pipe yet?

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On 5/13/2020 at 11:16 AM, GoNz0 said:

Did you replace with a new OE leak off pipe yet?

 Yes they are all replaced and sorted, I was thinking could there be a blockage to the pump or in the pump? Causing back pressure. 

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I totally forgot about this thread and always hate it when people don't update resolutions. I replaced the two injectors with the worst smooth running figures I think they were either -2.5 or +2.5 so not terribly out and haven't had a problem with return rail pressure since. It could possibly be if the injector is clogged it overly leaks back at a PSI greater than the leak back pipe can handle.

 

 

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