Fuel cuts

[flat tire]

I've been getting fuel cuts recently, first soft now hard. Have IE HPFP, 155 bar PRV.

From logs:

A) The good
--Low fuel pressure OK
--Battery voltage / alternator duty OK
--Great rail pressure tracking until fuel cut
--Relief valve works properly
--Cam follower visually confirmed good
--Brand new LPFP filter
--Brand new rail relief valve

B) The bad
--HPFP rail actual drops below requested, bottoming out somewhere in the double digits.

The car drives normally until put under moderate to heavy load and then actual rail pressure will dive from requested, now resulting in a hard fuel cut with throttle plate closing. Rail pressure will recover if the driver lets off and requests a low (stock) load. I suspect bad a N276.

Planning to buy a brand new HPFP w/ N276 and swap my IE internals. Good plan or should I consider something else?

 

[Red5pade]

The n276 is just a sensor on top. Just take it off and swap it.

 

[Red5pade]

What load was the lpfp under? I have no clue what you have in your car turbo wise.

 

[flat tire]

So, anyone live in Houston and want to temporarily swap N276?

I'd say it cuts out with any kind of sustained load around 150 or more. Just have a K04.

 

[Red5pade]

What was the load was the lpfp at? Is the n276 cracked.

 

[flat tire]

LPFP pressure remains high (between 4-5 bar) and duty cycle is not maxed when I have a cut.

Are you talking the valve status field in block 140? I haven't logged that during cuts, but will do so now.

 

[Red5pade]

LPFP pressure remains high (between 4-5 bar) and duty cycle is not maxed when I have a cut.

Are you talking the valve status field in block 140? I haven't logged that during cuts, but will do so now.

no, its 131 i want to say. if its higher than 70% then the lpfp is bad

also, try looking at the plugs and gapping them to 0.026 and switching to red tops. if the n26 isnt cracked then my guess is its not bad. just post your logs so people can take a look and possibly help.

 

[Red5pade]

sorry its 106. its been awhile

edit: whats your lambda. might advise against doing a log if youre running lean man

 

[flat tire]

I don't run lean until I actually get the fuel cut, and the ECU seems to be on top of instantly pulling load to avoid damage. It all happens within a fraction of a second. And 106 is good. Already logged.

In other news, I couldn't log today because my data blocks would go bad with the message "ERROR: GROUP ___ NOT AVAILABLE" randomly after less than a minute of being selected. I can reselect them and same deal. Guessing we have an issue with the can-bus. This has been an intermittent issue up to this point with blocks occasionally disappearing during long logs but today it was so bad I couldn't log at all.

I'll have to go thru my wiring and see what's up before drawing any conclusions.

 

[Red5pade]

Okay. Good luck figuring it out.

 

[taaj]

@flat_tire i have been living with this problem for quite a time now
my car got a k04 with s3 injectors apr hpfp, new fuel filter, new cam follower, new camshaft rev j, even bought the pcm heat sink and harness extension from @eurocars
swapped my apr hpfp with a new hpfp with IE internals, replaced my LPFP 3 times but in vain.

i thought replacing the pump from the lpfp would resolve the issue but still havent done or tried because i was hoping unitronic would resolve it with a revised tune