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keyap keyap is offline
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Join Date: Jun 2012
Car: N55 135i
Default 10-13-2018, 04:13 PM

Trying to figure out why my HPFP keeps crashing.
I'm using E60 mix for the moment, PI is working fine, Fuel trims are set to 25 across the board, AFRs are around 12.9 and 13.0 on boost, but my HPFP is crashing to 7 and getting misfires due to this.
Should I raise Fuel Bias even if Fuel Trims are holding on 25 on boost?

Hey ganque,

Could be a few things but at the levels you're running it may be worth trying to eliminate false knock as a cause. In some instances, I have seen it result in what appears to be misfires due to HPFP fuelling issues!

What BEF are you running and what do the LCM tables show? False knock manifests more in high load BEFs and there have been a few threads recently which speculate how E N55 knock sensitivity may increase relative to DME load targets. (It's worth reading Jay's thread here: https://www.n54tech.com/forums/showthread.php?t=54932)

If the LCM in the BEF is >160, try lowering to 150 and re-running to see if the HPFP behaves better. If it does then it probably is false knock. Make sure you log though and keep an eye on other fuel related parameters to make sure they are OK as changing the LCM can have other effects.

I also would not recommend running a decreased load target longer term unless you are comfortable 'tweaking' other parameters, especially if you are a DCT as it is directly linked to plate pressure, with lower load meaning less pressure and more slip. Terry has done quite a lot of R&D with regard to BEFs and having a higher LCM does has advantages. If you aren't a DCT it may be worth dropping Jay a PM as, I believe, pre his current setup he didn't have a DCT and by further experimenting with load targets and other parameters got the car running quite sweet. I seem to remember there are some of his posts somewhere about this. If you are a DCT then things become more complicated and limited!

It may also be worthwhile posting or linking your question to a new post in the forum support section (https://www.n54tech.com/forums/forumdisplay.php?f=45) as it's likely to trigger more responses.

You may also want to quickly check out this thread (https://www.n54tech.com/forums/showthread.php?t=38430). It was when I first had my PS2 and pretty much shows some of the first logs I grabbed on my current setup where I had similar HPFP issues. I initially suspected the pump/fuel setup, to later find it was false knock. The thread is a little outdated now given it's pre MHD. Also, larger turbo R&D was in quite an early stage so some content was speculation however the principle applies.

UK 2011 - E82- 135i - N55 - DCT

JB4 | BMS OCC | N20 TMap | Fuel-It! PI | AIC6 PI Controller | Fuel-It! Fuel Lines | Fuel-It! Stage 2 LPFP | Continental In-line E Sensor | ER Charge Pipe | Pure Stage 2 Turbo | Pure High Flow Inlet | GFB DV+ | Richter C'less D/Pipe | Berk Race Full Exhaust | MFactory Pro Helical LSD (75% Bias Ratio) | eDiff Disabled Via Coding | MFactory Solid Diff Bushes | Diff Lockdown Bracket | Custom 98G0B BEF | NGK 5992s (0.020")

Last edited by keyap; 10-14-2018 at 04:37 AM..
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Phataxe Phataxe is offline
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Posts: 146
Join Date: Mar 2018
Car: 2014 435I
Default Bosch Injectors. - 10-19-2018, 01:20 PM

So im tring to track down a problem with my Port Injection system. When the Injectors are connected to the Controller the 12v power going to the injector is seen on the Hot wire and the Negative wire. Should the 12v supply stop at the injector or does it back feed to the ground side until that wire is grounded to fire the injector?

'14 435I RWD MHD/JB4 "Twisted Custom BEF" XHP Trans Tune GFB DV+ Rev9 FMIC VRSF CP BMS Intake HP Down pipe Borla ATAK Exhaust Stage 2 LPFP BMP PI BMS PI controller EWG Harness Upgrade e85 3.5 TMAP NGK 5992 Plugs "0.020"
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