VR6 Fuel Pressure Regulator

[mnmv12 2]

I have been chasing a 00561 (Mixture Adaptation: Adaptation Limit (Add) Exceeded) error code for some time now and unable to clear it. The MAF is a new Bosch unit and I can’t find any air leaks in the intake system so my attention has turned to the fuel system. The car was in storage for many years so I am now thinking I have a faulty Fuel Pressure Regulator (FPR) or bad injector. I don’t currently have the means to test fuel pressure and as new Bosch FPR is cheap as chips I ordered one anyway. The new FPR which is listed on every website as being suitable for a 2.9 VR6 but has a different part number to the original and also has some visible differences. The most obvious is the return fuel port being considerably smaller in diameter.

Original

VW      078133534A

Bosch  0280160516

 

New

VW      078133534C

Bosch  0280160575

 

Both are rated a 4Bar but has anyone fitted this new Bosch part?  The original Bosch number doesn’t throw up anything on google except links to the new number or pre-owned ones.

To confuse things further Autodoc list a load of alternatives for 078133534A some of which look like the original some of which look like the new but they do not list a Bosch part. However, if you search the new 078133534c you do get the Bosch option and a load of different alternatives all of which are listed as being suitable for the VR6.

Would you fit the new one or buy a Pieburg equivalent (7.22017.50.0) of 078133534A which at least looks like the original.

Edited June 30, 2021 by mnmv12

[1xshaunx1 27]

I’m not sure but there is no guarantee the new maf is tiptop, can you borrow one off of a good running car and definitely cross that off of the list.

I think it’s called the erg valve that comes off of the top left of the cam cover and then joins into the air intake just before the throttle body. Basically a breather from the valve cover to the air intake, check this is ok and not spilling loads of oil into your intake and covering your maf and throttle body with oil rendering the maf useless

[fendervg 29]

For the FPR, once it's rated to the correct 4 bar, it should be fine - the outlet diameter shouldn't make a difference  as I think that's the return to the tank and the FPR's job is to maintain constant pressure in the fuel rail feeding the injectors and then dump excess fuel into the return, so the vacuum hose to the side is essential.

It's easy to test pressure using the small test nipple on the front left of the rail - as  simple pressure gauge is can be sourced pretty easily to attach to it, with a drain tap to release the pressure.

Are there any other symptoms apart from the 00561 (Mixture Adaptation: Adaptation Limit (Add) Exceeded) error? Engine fuelling seems to depend on a lot of sensors working together, such as the TPS, crank sensor, MAF and O2 and the blue temp sender in the thermostat housing.

[Bruno 4]

Agreed. The nozzle isnt going to make a difference. The same specific FPR is used on a Saab 9-5 in stage III, >300bhp, with no problems at all. Fendervg is right, this isnt a simple error. The 02 sensor feeds back the fuelling trim to the ECU. If the engine winds its idle speed up and down, or dies when dropping to idle, it could be that.  I'd start by having the injectors out and having them tested and cleaned. Any good motorbike tuning place should have that kit.  

[Dox 22]

http://wiki.ross-tech.com/wiki/index.php/00561
 

checking for vac / pcv air leaks would be the cheapest first option?

[mnmv12 2]

Thanks for the reply's. I have checked for any intake leaks including the evap operation and everything seems ok. The only real symptom of anything amiss is a lumpy idle. The inlet manifold is quite scruffy so when i pull that to clean it up it makes sense to have the injectors done. Mr injector is just down the road and at £17/ injector its not extortionate . The MAF, temp sensors, crank sensor, o2 sensor,coil, ignition leads, plugs, timing chains were all replaced 500 miles ago with genuine or branded parts when I re-commissioned the car. The throttle body is clean.

I have now fitted the new FPR but still have the 00561 code no other codes  are showing up, so more diagnostics required. Anything worth checking on VCDS?

Incidentally i purchased a new PCV valve from VW a month ago with next day delivery, Ford wanted £82 with a 2wk delivery, i thought it used to be the other way around?

[Dox 22]

Compression test, leak down even better