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Cold start issues - LPFP, HPFP, Injectors replacement - Results

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ZoliWorks:
Update again. Replaced HPFP with a Hüco unit. It's basically a Hitachi pump but with the Hitachi name grinded off and assembled in germany. After moving over the uprated internals, the pump seems to be more noisy than the old one under load. Cam follower was replaced with an INA part. Old one wasn't really worn out but figured might as well do it.

Now the thing is, I cant tell if it's my pump that sounds different or if my turbo has developed enough play to make noise while under load.

Changing the pump changed absolutely nothing. Fuel is still draining out of the fuel rail after letting the car sit. I'm changing the injectors with brand new oem S3 ones and installing a new oem rs4 fprv before getting remapped. Hopefully this will sort my fuel leak issues.

Mekaniko:
I've been searching for the long cold start on AXX-BWA for years and never found the solution. I don't want to start changing parts without a clear pad... injectors? Who knows.

ZoliWorks:

--- Quote from: Mekaniko on February 10, 2025, 11:36:43 am ---I've been searching for the long cold start on AXX-BWA for years and never found the solution. I don't want to start changing parts without a clear pad... injectors? Who knows.

--- End quote ---

I'll update this post once I fit the injectors. Ordered them today and should arrive tomorrow, but will only be fitting next week when I'm also remapping for a proper k04 tune.

I have:

* New Continental LPFP
* New Hüco HPFP with VIS InternalsSoon:

* New S3 Injectors and a complete mounting kit (seals, baskets etc)
* New Fuel Pressure Release Valve
* New Bosch N80 Valve
It has to be something on the high pressure side of the HPFP/Fuel Rail. When I unbolted the high pressure side from the pump, nothing came out. Literally 0 fuel. When I did the low pressure side, some fuel came out. The LPFP relay was disconnected for an entire day at that point so it didn't pump any fuel when I opened the door.

mjmallia:
Changing my LPFP made a big difference for me, as the old pump must have been worn out at 120K miles.

I am taking out my injectors tomorrow to change the baskets, seals and generally clean/service them......as been seeing loads on basket failures recently.........every little bit helps and it is preventative maintenance in my eyes.

At the same time I am also going to check on the inlet valves while it is all off as cleaned them 20k miles ago, curious to there condition as they were really bad when I did them the first time.

All parts collected and have the day off to attack it  :scared: :grin:

ZoliWorks:
Another thing I've heard is that the fuel lines can develop cracks and air can get through them, into the fuel feed. If all else fails, this is also something I wanna look into. I'll replace certain parts of the fuel lines with transparent tubes just to see what's up while the engine is running.

Good luck with your injector stuff!

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