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-   -   Need help...29DC Injector Cutoff....HPFP? See log! (https://www.n54tech.com/forums/showthread.php?t=66454)

iqraceworks 09-12-2021 11:24 AM

Need help...29DC Injector Cutoff....HPFP? See log!
On the way home from work yesterday I was cruising on the highway around 70mph....as I rolled on the gas a little bit to get around a car, the car fell on it's face (no power) and started shaking pretty bad. I pulled over where I could, and shut the car off....started it back up, and it ran just fine. I took it easy on the way home.

When I got home I scanned for codes...29DC injector cutoff, 2FCA Fuel High Pressures, and 29F1 fuel possibility. I let the car sit overnight, and fired it up again in the morning...it only idled for a couple of seconds before it choked out and died. Unfortunately I didn't have MHD hooked up so I could see what was going on with the fuel pressures. So I hooked it up, started a log, and then fired up the car again....ran great, smooth idle, fuel pressures all looked great??

So then I took the car for a drive while pulling a log. As you can see, as soon as I started rolling onto the throttle, the HPFP pressure starts to build and then up around 2,600psi...it just falls on it's face down to 400psi....and then the car started running rough again (29DC Injector Cutout).

Is that what happens when a HPFP starts going bad? Starts to build pressure fine...and then just tanks? I wish I could get it to fire up and idle really rough while pulling a log.....but so far, I can't get it to repeat that again.

Check out this log...Do I need to replace the HPFP? Or could it be a sensor issue??

(LPFP is pretty new...Walbro 450. I'm running a custom 93 octane tune wit RB TWO's. A few weeks ago I was running my e40 tune at 26psi...and the logs showed the HPFP pressures to be great....no indication of issues.


Steve @ BMS/Fuel-It! 09-13-2021 10:06 AM

For us to look at a JB4 log, you'll need to post the CSV file.

iqraceworks 09-13-2021 06:48 PM

So...I went out tonight after work and tried to get a nice clean log showing what's going on. I slowly rolled onto the throttle in 3rd gear.

As I'm rolling into the gas in 3rd gear, at around 3,000rpms with only 4psi of boost the HPDP pressure just tanked...it dropped from around 1,200psi down to 215psi. As soon as I let off the throttle, it bounced back up to 2,800rpms.

Both banks STFT jumped up to 34% (trying to correct a lean condition). If this was a stuck injector, I don't think both banks would be equal...one would be way rich or way lean....right?

At this point........I'm pretty sure it's a HPFP issue. What am I missing here?


Steve @ BMS/Fuel-It! 09-14-2021 10:54 AM

You're missing the CSV file. ;)

iqraceworks 09-14-2021 11:09 AM

1 Attachment(s)
Here you go ;)

iqraceworks 09-14-2021 06:10 PM

1 Attachment(s)
Well....I gave it one more shot before I ordered a new HPFP. First, I checked all the plugs after the car sat all day...all dry and look fine (no leaky injectors). Then I hooked up MHD, got a log running, and fired up the car.

This time the HPFP never got above 50psi...the motor sputtered and coughed as it attempted to idle. After doing that for around 10 seconds, the HPFP came to life and the pressure sprung up to around 2,600psi and the motor started to idle normal.

At this point....I'm 110% sure it's a HPFP problem. I think something is jacked up with the built in fuel pressure regulator. I'm going to order a new one off of FCP Euro tonight, along with a new rail pressure sensor.

I will report back after the parts show up and I get to take the car for a test drive. :thumbsup:


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