[kevlarblue]

Cold starts are fine - fires right up and runs smooth. But if I start the car within 30-40 minutes after shutting down (still warm) it cranks for a long time and stumbles a bit when it does fire up. It will smooth out pretty quick but it's been driving me crazy.

I also have the shadow code 2FDB Fuel High Pressure nach freigabe der Einspritzung which apparently means pressure not building at start - almost exactly what I am experiencing but only during warm starts.

Through all my research and reading the forums my 2 leading theories are HPFP or leaking injectors. Since both are fairly expensive I don't want to throw either part at it without another opinion. So far I have done:

Coils and plugs last weekend
Walnut blasting ~3K miles ago
Crank position sensor 500 miles ago
The test with injectors out of the motor and cranking (none of them leaked)

The tips of my index 12 injectors were pretty black when I pulled them out (normal?) and I do smell fuel around the car occasionally. But I couldn't get any of them to show me a leak and none of the plugs smell like fuel when I pull them out.

Other than the hard start the car runs great - no fuel starvation symptoms and no active DME codes. I am FBO with stock turbos and JB4 at 112K miles. I'm either going to spend the money and get a new HPFP (out of extended warranty coverage) or swap my injectors for used index 12s.

I'm hoping to poll the crowd: which of the 2 expensive options will fix my hard starts? Thanks for reading - I appreciate any input.

[swellengear]

Sounds like you might have a small leak on an injector, although the code points towards a hpfp issue. Are you able to post a log?

If this only happens when warm, try pulling the plugs after 45mins and see if any of them are wet/damp with fuel. Leak may be small enough that the plug(s) dry out while it cools - so no cold start issue.

[kevlarblue]

Originally Posted by swellengear

Sounds like you might have a small leak on an injector, although the code points towards a hpfp issue. Are you able to post a log?

If this only happens when warm, try pulling the plugs after 45mins and see if any of them are wet/damp with fuel. Leak may be small enough that the plug(s) dry out while it cools - so no cold start issue.

I did the try the plugs while it was warm and it was inconclusive - I had just done the injector test and there was fuel everywhere.

I can definitely post a log from the JB4, would a warm start with issue be the most helpful? Or just a pull?

[kevlarblue]

Originally Posted by swellengear

Sounds like you might have a small leak on an injector, although the code points towards a hpfp issue. Are you able to post a log?

If this only happens when warm, try pulling the plugs after 45mins and see if any of them are wet/damp with fuel. Leak may be small enough that the plug(s) dry out while it cools - so no cold start issue.

Here is a 3rd gear pull from my JB4. I'm working on getting MHD installed in case this doesn't make sense to anybody else.

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[marcell1401]

Any news on this? I have exactly the same issue. Injectors dont leak. Stumble on hot start. Plugs and coils are new and gapped correctly. Maybe an air leak or bad o2? I habe read that cold start runs from ecu values and hot start ist based on map/maf and o2 afr.