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Audi A3 2.0 CBAB 2009 - Stalls, low fuel pressure, code P0087 - Unresolved #

Posted by Chris Angus on February 13, 2017, 1:44 pm

Year of Manufacture *: 2009
Engine Size and Code *: 2.0 CBAB
( Optional) Fault Codes: P0087 fuel pressure too low

No looking for an answer to this fault, but looking for views how to actually test and prove where the fault is.

This car dives ok but when you let off the accelerator the fuel pressure drops and stalls, no other issues.

This setup has in tank lift pump, supplementary fuel pump, high pressure fuel pump with IMV and fuel rail with pressure regulating valve.

I have spent some time this morning checking the pre supply and it will happily maintain 4bar to the HP pump, so this rules out the pre supply.
I have removed the IMV and checked for any swarf but it's nice and clean.
Injector leak off test was fine too.
So, If I give this a good rev and let off it will reach 1200 bar and drop to 100 bar and stall, it will restart instantly, so I am assuming that the HP pump is ok as it will make 1200 bar, this now leaves the pressure regulator in the rail.
These parts are not cheep and I'm reluctant to play parts darts with this, so the question is, is it possible to prove where the fault is, pump or reg?

Also, I can see an increase in current at the pressure reg just before it stalls, so It does look like it's trying to increase pressure but can't fast enough.

Just found an interesting read here
https://www-odi.nhtsa.dot.gov/acms/cs/jaxrs/download/doc/UCM475595/INCR-EA11003-61863.pdf

Re: Audi A3 stalls, low fuel pressure

Posted by andrew young <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5148' width='330' height='300' border=0 style='border:none;'> on February 13, 2017, 5:47 pm, in reply to "Audi A3 stalls, low fuel pressure"
Andrew Young

This may be completely off target,but I would check to make sure the pipes to the fuel filter housing are located on the correct locations.Easy to get them wrong if they have been removed after a filter change.

Re: Audi A3 stalls, low fuel pressure

Posted by Jon Morgan <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3190' width='330' height='300' border=0 style='border:none;'> on February 13, 2017, 9:47 pm, in reply to "Re: Audi A3 stalls, low fuel pressure"
Jon Morgan

I seem to recall there is a test in ELSA for the DRV on a CBAB which involves checking the rail return for flow quantity.

Have you looked in ELSA for this test, I may be getting confused as i've done a few recently.

Is it hunting at idle, or will it not idle at all?

Re: Audi A3 stalls, low fuel pressure

Posted by John Corrigan <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3173' width='330' height='300' border=0 style='border:none;'> on February 13, 2017, 11:13 pm, in reply to "Audi A3 stalls, low fuel pressure"

Hi Chris, on your A3 cutting out, Wthat type High Pressure pump have you got,I assume its a Bosch CP3 without the gear pump fitted to the back of the H/P pump, 4 bar would be about normal.do you have live data and check the rail pressure before it cuts out, normally about 200 > 400 bar, if no live data check the voltage reading from H/P sensor, 3 wires, 5v feed,earth,and signal wire, normally centre wire(ign on.5v )( start.98 > 1.2v ) full throttle 4.5v. my moneys on the Regulator on pump mechinically sticking,2 wire elect connection.Remove from pump,3 bolts,SPECIAL Tool required (6 mm woodscrew)you'll see what looks like a washer pump end of reg,screw woodscrew into washer, catch screw in vice and tap reg and washer , remove piston and spring, clean piston and bore until free, reassemble and test. John

Re: Audi A3 stalls, low fuel pressure

Posted by Chris Angus <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat5111' width='330' height='300' border=0 style='border:none;'> on February 14, 2017, 10:49 am, in reply to "Re: Audi A3 stalls, low fuel pressure"

Thanks Andrew, it was the first thing I checked

Re: Audi A3 stalls, low fuel pressure

Posted by Chris Angus <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat5111' width='330' height='300' border=0 style='border:none;'> on February 14, 2017, 10:52 am, in reply to "Re: Audi A3 stalls, low fuel pressure"

Think it's cp4, the reg on the pump is an IMV and I did remove it to check for swarf, didn't want to try take it apart, it's not available separately.
The pressure reg is on the rail.

Re: Audi A3 stalls, low fuel pressure

Posted by Chris Angus <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat5111' width='330' height='300' border=0 style='border:none;'> on February 14, 2017, 11:07 am, in reply to "Re: Audi A3 stalls, low fuel pressure"

Had a look on elsa but strangely couldn't see anything for fuel pressure or rates, had to ring autologic for that.

It runs fine, just stalls sometimes when you let off accelerator

Re: Audi A3 stalls, low fuel pressure

Posted by Jon Morgan <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3190' width='330' height='300' border=0 style='border:none;'> on February 14, 2017, 11:16 am, in reply to "Re: Audi A3 stalls, low fuel pressure"

Hi Chris, the test for Fuel Pressure Regulating Valve N276 is in ELSA, I just looked.

Go into ELSA Workshop Repair Guide and type N276 in the search box top right, it takes you straight to the test plan.

Jon.

Re: Audi A3 stalls, low fuel pressure

Posted by Chris Angus <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat5111' width='330' height='300' border=0 style='border:none;'> on February 14, 2017, 11:18 am, in reply to "Re: Audi A3 stalls, low fuel pressure"

Which section?

Re: Audi A3 stalls, low fuel pressure

Posted by Jon Morgan <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3190' width='330' height='300' border=0 style='border:none;'> on February 14, 2017, 11:19 am, in reply to "Re: Audi A3 stalls, low fuel pressure"
Jon Morgan

See my reply above which I just edited.

Re: Audi A3 stalls, low fuel pressure

Posted by Chris Angus <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat5111' width='330' height='300' border=0 style='border:none;'> on February 14, 2017, 11:24 am, in reply to "Re: Audi A3 stalls, low fuel pressure"

Yep found it, was looking in the wrong place, will try and get car back and test again.

Re: Audi A3 stalls, low fuel pressure

Posted by John Corrigan <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3173' width='330' height='300' border=0 style='border:none;'> on February 14, 2017, 12:32 pm, in reply to "Re: Audi A3 stalls, low fuel pressure"

Chris, If the pump is a CP4 be very very careful as they have a history of breaking up. My understanding of the CP4 system is the reg ( - control) on the pump controls the basic H/P but the one on the rail fine tunes it and also acts as a pressure limiter. With - control regs if theirs no current to the reg the rail pressure increases and the reg on the rail takes over and gets you home in limp mode.The + control doesn't have a limiter on the rail.The first thing we do in workshop is check what pump is fitted,if it's + or - regulator as all regs look the same, if its a CP4 we treat with kid gloves.

Unresolved #

Posted by Chris Angus on April 26, 2017, 2:31 pm, in reply to "Audi A3 2.0 CBAB 2009 - Stalls, low fuel pressure, code P0087 #"
Edited by board administrator April 27, 2017, 11:31 am

customer didn't want to pay for testing, so sent him away

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