[PabloK]

Sorry if this has been beaten to death.

N55 - EWG Pure stage 2 with strictly 93.
proper plugs and gap
Bootmod3 flash, many tune revisions - same issue (on new v5)
No desire for E85
running factory fuel pump that was recalled couple years back

Full throttle, car hits about 4-5,000 RPMs and will start cutting out/backfiring. I will literally get thrown forward in my seatbelt the backfire/engine cutting is so pronounced

I sent an older data log (stage2 -93 octane V1) to Steve at Fuel-it.

http://www.bootmod3.net/log?id=5a197cb2d10b435804b57440

His excellent response.

Your HPFP requested pressure is 2800psi but your rail pressures are dropping to 1200psi. Pretty common on the F-series N55 as the HPFP is pretty weak on those cars.

Adding port injection will resolve the HPFP limitations. If running just 93 you can stick with an Stage 2 LPFP as that will be sufficient. However on the F-series, we often recommend a Stage 3 LPFP because it retains the stock LPFP during normal driving conditions and then activates the secondary under highboost. That saves wear and tear on the EKP that controls the LPFP and prevents it from overheated due to additional current draw from the upgraded pump. That also eliminates possible iDrive errors for the additional current draw.

This stuff is pretty much over my head/new territory. Has anybody had similar issues and does this make sense? I've read many posts saying the fuel pump upgrade is not needed for 93 stage2 but i need another opinion.

Do i go with a stage 3 or Port injection?

[M-terkait]

I doubt you need it just for pure stage 2 on 93octane, I use PI with 93octane for my doc-race but when I had pure turbo I was already at the limit of octane anyway didn't need to use PI.

anyways i use stage 2 lpfp and PI. 450walbro should support up to 700hp on pump gas

Edit: Request tune update from PTF, if they could help even if you lose 10-20hp its not worth gaining 20hp and get PI + controller + Lpfp stage 2.

[PabloK]

So stage 3 might be overkill but I'm reading the stage 2 can sometimes cause I-drive errors.

Seems like the stage 3 is a more complete package without any potential issues down the road

Stage 2 can cause additional current draw on the EKP to run that pump.

That alone would push me to the stage 3...

[SeanWRT]

Did you just send the wrong log link? HPFP is fine from that one. Post the log with falling HPFP please.

Needing additional fueling or not depends on how hard and what range of RPM you push it. On pump gas, octane limit comes at the same time as, if not a little earlier than fueling one, if it's tuned properly.

[zinner]

Pablo you are at the end of the road on the N55 if you don't want to do E85. Just lower the boost target to around 16 and be happy :-D Assuming from your location it's really cold out, you can't hit the same boost targets in the colder air, just not enough fuel can be delivered.

[PabloK]

Originally Posted by SeanWRT

Did you just send the wrong log link? HPFP is fine from that one. Post the log with falling HPFP please.

Needing additional fueling or not depends on how hard and what range of RPM you push it. On pump gas, octane limit comes at the same time as, if not a little earlier than fueling one, if it's tuned properly.

I'll make a fresh map tomorrow

[PabloK]

Originally Posted by SeanWRT

Did you just send the wrong log link? HPFP is fine from that one. Post the log with falling HPFP please.

Needing additional fueling or not depends on how hard and what range of RPM you push it. On pump gas, octane limit comes at the same time as, if not a little earlier than fueling one, if it's tuned properly.

isn't this it?
Thats full throttle... and the drop in HPFP ACT. directly correlates to when I'm getting cutting out.

I'll do a new log tomorrow, I just flashed v6...

[PabloK]

Originally Posted by zinner

Pablo you are at the end of the road on the N55 if you don't want to do E85. Just lower the boost target to around 16 and be happy :-D Assuming from your location it's really cold out, you can't hit the same boost targets in the colder air, just not enough fuel can be delivered.

I believe I'm around 16.5 Boost. New log coming tomorrow, supposed to be in the 50s

[PabloK]

Originally Posted by M-terkait

I doubt you need it just for pure stage 2 on 93octane, I use PI with 93octane for my doc-race but when I had pure turbo I was already at the limit of octane anyway didn't need to use PI.

anyways i use stage 2 lpfp and PI. 450walbro should support up to 700hp on pump gas

Edit: Request tune update from PTF, if they could help even if you lose 10-20hp its not worth gaining 20hp and get PI + controller + Lpfp stage 2.

Could I theoretically just get stage 3 and be done with it? Why skimp I'm this deep in?

[JaredG_F30]

Buy nice or buy twice!! Go for it.

Originally Posted by PabloK

Could I theoretically just get stage 3 and be done with it? Why skimp I'm this deep in?

[SeanWRT]

It seems to be HPFP failing to keep rail pressure. But doesn't tell the whole story. Post the log link. It takes full data to know where and how. There're plenty of OTS users doing fine on stock fueling. Chances are you're an isolated case.

Originally Posted by PabloK

isn't this it?
Thats full throttle... and the drop in HPFP ACT. directly correlates to when I'm getting cutting out.

I'll do a new log tomorrow, I just flashed v6...

[zinner]

Originally Posted by SeanWRT

It seems to be HPFP failing to keep rail pressure. But doesn't tell the whole story. Post the log link. It takes full data to know where and how. There're plenty of OTS users doing fine on stock fueling. Chances are you're an isolated case.

He already posted the link you just looked at the wrong part of the log.

[PabloK]

Originally Posted by JaredG_F30

Buy nice or buy twice!! Go for it.

Thanks for the help boys. It's much much appreciated.

I'll get a lot today!

[M-terkait]

Originally Posted by PabloK

Could I theoretically just get stage 3 and be done with it? Why skimp I'm this deep in?

I run stage 2 lpfp with PI on pump gas, walbro450 in this stage 2 can deliver alot for pump gas, and on ethanol thats enough, you can still upgrade to stage 3/4 later for the fraction of the price.

stage 3 runs sequential two-lpfp not sure how is it triggered, but stage 2 is much simpler and more than enough for your pure stage 2.

[IK6SPEED]

Originally Posted by PabloK

Sorry if this has been beaten to death.

N55 - EWG Pure stage 2 with strictly 93.
proper plugs and gap
Bootmod3 flash, many tune revisions - same issue (on new v5)
No desire for E85
running factory fuel pump that was recalled couple years back

Full throttle, car hits about 4-5,000 RPMs and will start cutting out/backfiring. I will literally get thrown forward in my seatbelt the backfire/engine cutting is so pronounced

I sent an older data log (stage2 -93 octane V1) to Steve at Fuel-it.

http://www.bootmod3.net/log?id=5a197cb2d10b435804b57440

His excellent response.

Your HPFP requested pressure is 2800psi but your rail pressures are dropping to 1200psi. Pretty common on the F-series N55 as the HPFP is pretty weak on those cars.

Adding port injection will resolve the HPFP limitations. If running just 93 you can stick with an Stage 2 LPFP as that will be sufficient. However on the F-series, we often recommend a Stage 3 LPFP because it retains the stock LPFP during normal driving conditions and then activates the secondary under highboost. That saves wear and tear on the EKP that controls the LPFP and prevents it from overheated due to additional current draw from the upgraded pump. That also eliminates possible iDrive errors for the additional current draw.

This stuff is pretty much over my head/new territory. Has anybody had similar issues and does this make sense? I've read many posts saying the fuel pump upgrade is not needed for 93 stage2 but i need another opinion.

Do i go with a stage 3 or Port injection?

So he is saying you need a $1k Stage 3 LPFP and a $1.5k port injection?

[PabloK]

Originally Posted by IK6SPEED

So he is saying you need a $1k Stage 3 LPFP and a $1.5k port injection?

his message was confusing... I initially thought the same thing.

I'm going with the stage 3 to avoid idrive errors.

[PabloK]

Originally Posted by M-terkait

I run stage 2 lpfp with PI on pump gas, walbro450 in this stage 2 can deliver alot for pump gas, and on ethanol thats enough, you can still upgrade to stage 3/4 later for the fraction of the price.

stage 3 runs sequential two-lpfp not sure how is it triggered, but stage 2 is much simpler and more than enough for your pure stage 2.

its triggered with some electrical switch, it's fully automatic.

I'm sure stage 2 is sufficient, but I don't want to fuck with i-drive errors. thats a deal breaker for stage 2

stage 3- overkill but better overall package with less potential issues down the road. I want the car to run properly, I'm not going to decrease boost if the issue can be fixed for $900.

[ronanz]

Originally Posted by PabloK

its triggered with some electrical switch, it's fully automatic.

I'm sure stage 2 is sufficient, but I don't want to fuck with i-drive errors. thats a deal breaker for stage 2

stage 3- overkill but better overall package with less potential issues down the road. I want the car to run properly, I'm not going to decrease boost if the issue can be fixed for $900.

I've never experienced iDrive errors...

.

[SeanWRT]

OP, your map isn't aggressive at all. Need to fix boost control on gear shift. All in the tune. You don't need additional fueling.

[PabloK]

Originally Posted by SeanWRT

OP, your map isn't aggressive at all. Need to fix boost control on gear shift. All in the tune. You don't need additional fueling.

Does BM3 do flash revisions on the ots maps?

Thanks for the help guys......

[PabloK]

Originally Posted by ronanz

I've never experienced iDrive errors...

.

Maybe just some isolated cases? Just the info I got from fuel it. Thanks for the input.

[M248]

Hey man did you ever figure this out? I’m having the same issues with my F33 N55 using any variant of the it’s stage 2 MHD tune. My stft’s are super positive around +20%. I’ve also had the lpfp recall. I notice when my stft’s are positive and I enter high boost, my HPFP dips from requested and I get throttle and boost cut as a result. I get the same stuttering symptoms too, just not backfires and heavy lurches.

A forum member who also custom tunes was king enough to send me a stft fix map, but running e20 my stft’s are still very positive, and HPFP issues remain.

I ended up purchasing stage 3 lpfp for the same reasons you cited. I also ordered EOS PI with jb4. I’ll be upgrading to ps2 and want to run full e85 which is plentiful in Michigan, with minimum ethanol contents of 70%.