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Precison Raceworks Stage 3 LPFP DIY/Tips

iwannagofast

iwannagofast

Not a Newbie
Location
Severn, MD
Car(s)
'17 GTI
aaronc7 said:
Injection angle is related to injector timing which is based on exhaust cam position, ign timing, injector pulsewidth etc. Not really relevant here. Injector pw is. You normally see injector pw spike when high side fuel pressure drops etc. Positive STFT literally is commanding additional injector pw.
Click to expand...

So I was looking back through my old logs, and HPFP eff pump vol % wasn't maxed out on 93 octane. As soon as I got the base tune for E85, it's been pegged at 100 and there ever since.

It makes sense what you're saying about injector pulse width, but where is that on my logs?
 
aaronc7

aaronc7

Autocross Champion
Location
USA
Car(s)
17 S3
iwannagofast said:
So I was looking back through my old logs, and HPFP eff pump vol % wasn't maxed out on 93 octane. As soon as I got the base tune for E85, it's been pegged at 100 and there ever since.

It makes sense what you're saying about injector pulse width, but where is that on my logs?
Click to expand...

Well that explains that and the higher than normal fuel pressure, pushing the limits of the fuel system. I'm guessing he's logging all of that injector timing stuff because again you're right at the limits of what's possible. "SOI" is start of injection and "EOI" is end of injection.

Like you said if you changed something and saw that significant change in STFT then maybe it is good to go. I also notice in your first log it's actually a little lean at the top end. Only 0.2 off, but these cars tend to be dead nuts on stuff is working. 2nd and 3rd logs AFR is spot on.

It still seems strange for me to see HPFP eff volume in the 80s at low rpm/peak torque.....then increase and flatline at 100 for the rest of the pull. Maybe they are doing something with injection timing that makes the math wonky and not display correctly, IDK.

Either way I'm super paranoid about LPFP because of all these issues, lol. If I do it, I'm tempted to install an inline pressure sensor/fitting in the fuel line so I can monitor the low side.

https://datazap.me/u/ssjneko1/log-1590080913?log=2&data=6-15-19&solo=6-18-19-35
 
iwannagofast

iwannagofast

Not a Newbie
Location
Severn, MD
Car(s)
'17 GTI
Both of those are great ideas. I noticed the AFR too. I didn't know if .2 was "too lean", but if these cars are dead nuts, then it's definitely indicative of something going on. I think I'm not going to touch the lpfp and wait for EQT's response. I'm hoping I'm at the end of the tuning (currently on revision 9) and I've just hit a wall on fueling. Since I'm running full E85, they might even tell me to pull back to E60 or so.

I will add MPI eventually when I go hybrid turbo. I regret not doing any of that in the first place based off my lpfp issues.
 
iwannagofast

iwannagofast

Not a Newbie
Location
Severn, MD
Car(s)
'17 GTI
So EQT got back with me and said the way I'm reading the graphs is correct. Cylinder 1 Injector End Angle should never bottom out the way that it does at 6100rpms. That means that the data log with the new revision showed the fuel pump failing again.

Fuel pump failing: https://datazap.me/u/ssjneko1/log-1590592626?log=0&data=10-15

So I removed the LPFP for the 9th time and did some trimming around the top so the O-ring can seat all the way down. I then zip tied it into place. I've seen people do this with the green top hat, but not with the blue one. If anyone has advice to keep this sob in place, please let me know.
LPFP2.jpg

LPFP3.jpg


I then did some more logs:

O-ring fully seated and zip tied: https://datazap.me/u/ssjneko1/log-1590592626?log=2&data=10-15-35
You can see that the Injector End Angle never bottoms out and my STFT% never starts creeping up...fixed right?

I logged rowing through the gears and I noticed a slight hesitation at the end of 3rd gear...is it a fuel cut?
3rd and 4th gear: https://datazap.me/u/ssjneko1/log-1590592626?log=1&data=10-15-35
You can see right at the end of 3rd gear at 6400rpms, the Injector End Angle bottoms out and that's right when I got the fuel cut. 4th gear looks perfect though.

I'm at a loss. I've verified my basket isn't leaking at all...0 drips... the o-ring is fully seated and zip tied into place. What else could be failing? The venturi or the filter? A new O-ring perhaps? Does anyone know where I should go from here?

Sorry for the long posts, but I wanted to make sure all of this gets documented in case someone else goes through these same issues.
 
iwannagofast

iwannagofast

Not a Newbie
Location
Severn, MD
Car(s)
'17 GTI
Diggs24 said:
Why are you running it at 94% duty?
Click to expand...

Don't know, it's part of the tune I suppose. What should it be at? Looking at my logs, it was pegged at 92 up until the 5th revision and it's been at 94 for the past 3 revisions. EQT told me to take some time and drive the car for a while and get my LPFP straightened out before they send their next revision.

Edit: Also EQT told me that last 4th gear pull looked great btw.
 
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iwannagofast

iwannagofast

Not a Newbie
Location
Severn, MD
Car(s)
'17 GTI
Diggs24 said:
Unless you have a PM4 I didn't think you could run a 450 out past 82% duty. The controller will overheat and die.
Click to expand...

Don't know, I asked this question on 2 separate occasions on the EQT Facebook group and to my tuner himself and they all said it's fine without PM4 and they account for the controller duty in other ways, but didn't get into details. 🤷‍♂️ I asked if I needed to change anything via VCDS or add a larger ground and I was told no.
 
aaronc7

aaronc7

Autocross Champion
Location
USA
Car(s)
17 S3
Are we absolutely certain it's a LPFP issue? High side pressure is rock solid, if the low side was not supplying enough fuel, I would think we'd see something weird going on with high side fuel pressure..a few big dips...something.

I did a little more digging / math with the injection timing stuff to see if anything looked out of place. My hunch here is that you may be running out of injection window up top. Combination of DI and high rpm means you have a very very small time period to get all the fuel you need in, and with straight E85 that becomes more challenging.

I created a new column in the datalog that computes the injector pulsewidth based off the logged SOI and EOI crank angles... If you do SOI - EOI that equals the degrees of crank rotation that cyl 1 is firing the injector. I then converted crank angle in degrees to time in ms, based on engine RPM at that particular point. This should closely match the logged injector pulsewidth param.

The logged injector pw and calculated injector pw params line up very close during the whole pull, except after 6100 rpm. To me it looks like injector pulsewidth commanded > injector pulsewidth allowed by ECU limits or whatever. This would indicate you're running out of injector or 'injector window'.

What's interesting to me is AFR is still spot on. But again to me all these issues seem to point to running out of injector, not LPFP.

Let me know what you guys think.

https://datazap.me/u/aaronc7/e85-injector-pw-data?log=0&data=5-6-10

inj pw - logged injector pulsewidth param
pw comp - calculated injector pw based off logged SOI and EOI params.
 
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aaronc7

aaronc7

Autocross Champion
Location
USA
Car(s)
17 S3
Up top he's injecting for like 330-350* of crank rotation.... I don't know exactly when the exhaust valve is closing, but he is running 15* of ign advance. It's hard to imagine he isn't spraying fuel when the exhaust valve is open and getting very very close to the spark event. Very much so pushing the limits of the fuel system and I fear what's going to happen when the temps get in the 30s or whatever. Based on what I can see, either way probably too close to the limits for comfort for me personally. This kinda data shows me that MPI is definitely the way to go for straight E85 on IS38 even. Might be smarter overall to run E50 or so. My 2 cents anyways.

1590616118530.png
 
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