[dreptroman]

Hey guys. I have some issues with my 90k miles e93 n54 2007

When starting the idle is rough and sometimes even drops to 200-400 rpms. At wot i sometimes get limped and a 29DC code shows up.

I have not changed the HPFP nor the LPFP and I am trying to determine which I need replaced.

This is a log with cold start. The fuel pressure jumps up and down between 60 and 80

Any ideeas which one is going bad?

This is a log pulled with MHD

http://www.datazap.me/u/dreptroman/1-dec

Thx for any input

2FDB 2FCA 2FDA and

2DED are also present

[dreptroman]

http://www.datazap.me/u/dreptroman/9-nov

And this is a WOT log

[CarAbuser]

Sounds like HPFP to me.

From the WOT run they both look fine but those poor starting symptoms sound like what I went through with my HPFP.

When my LPFP went I was suffering from long cranks but once it fired up it was fine. No problems holding idle.

I'm not sure all failures are equal though. I think sometimes the pumps can't meet pressure requirement and other times they struggle holding fuel pressure when the engine is off which is what was causing my long cranks.
I think the logic for priming the fuel pumps assumes that the lines will be pressurised for a while so doesn't re-prime them on warm starts. That was my thinking anyway.

[Antetokounmpo]

Both look fine in the wot log. Rail pressure is well above 1000psi and the lpfp is well above 50psi.

[Jklad]

I was having occasional rough cold starts for over a year. Idle would dip below 400 and back up for about 3-7 seconds upon cold start in the morning. Symptoms were similar to injector issue, except in my case it was the hpfp.

[xcusem3]

Originally Posted by dreptroman

Hey guys. I have some issues with my 90k miles e93 n54 2007

When starting the idle is rough and sometimes even drops to 200-400 rpms. At wot i sometimes get limped and a 29DC code shows up.

I have not changed the HPFP nor the LPFP and I am trying to determine which I need replaced.

This is a log with cold start. The fuel pressure jumps up and down between 60 and 80

Any ideeas which one is going bad?

This is a log pulled with MHD

http://www.datazap.me/u/dreptroman/1-dec

Thx for any input

2FDB 2FCA 2FDA and

2DED are also present

I've got these same codes in the past but I had quite different symptoms than you are having. She fires up and idles with no issues what so ever, the problem starts when I get on the freeway and give it a little. It's almost as if the car builds fuel pressure, loses it momentarily, then instantly builds it back up again during mid-rpm high load situations. I replaced the hpfp last year so I would assume it hasn't crapped out again. I've been advised it could possibly be tune related, but I've been running the same map for over a year with no issues until recently. Tonight I'll flash back to stock and see if the problem persists.