[SoCalM235iR]

Yeah I know it sounds crazy to run it on the track with these issues, but as I wrote earlier, I was ready to swap the stock tune back in, but I ran some logs and saw no timing corrections or spark knock and the fuel pressure dropped only 200 psi in the worst case.

IAT's on track were 140-150. Not sure why they were so high in those posted logs Hmm... Am I correct that as IAT's rise timing and boost are reduced?


Normally I track a prepared ZO6, but the BMW had to fill in this time.

[thejeremyman9]

Originally Posted by SoCalE90

Yeah I know it sounds crazy to run it on the track with these issues, but as I wrote earlier, I was ready to swap the stock tune back in, but I ran some logs and saw no timing corrections or spark knock and the fuel pressure dropped only 200 psi in the worst case.

IAT's on track were 140-150. Not sure why they were so high in those posted logs Hmm... Am I correct that as IAT's rise timing and boost are reduced?


Normally I track a prepared ZO6, but the BMW had to fill in this time.

Yes, with high IATs the DME will pull timing. Typically boost target is not reduced, although it may be in a very extreme case if the DME goes into full protection mode and starts the close the throttle as well. However i highly doubt you saw no timing corrections with IATs that high... even with good IATs (well below 100F) timing corrections are almost inevitable. And in the log you posted (i looked at 2nd one) you had more and more timing being pulled as IATs increased later on in the pull and you were down to only ~2 degrees on some cylinders.

Anyways didn't mean to go off topic from the fuel pressure issue was just stating my recommendation for an IC, certainly if you are going to track. The DME is good at protecting the engine but tracking without a IC upgrade, especially when tuned, is crazy to me.

[SoCalM235iR]

Your comments are helpful and relevlent. Appreciated.

[n55david]

Originally Posted by thejeremyman9

That is strange if even the M2 tune has an issue... that makes me a little suspicious it could be software.

I use this kit: https://www.amazon.com/gp/product/B0...UTF8&psc=1

I would avoid the knock off ones and just get the fuel-it one.

I can't believe you tracked the car with this tune and no IC lol... did you check IATs? They rose 50F in that one pull you posted, i can't imagine what they were at the track.

oh god you're right.. yikes

[SoCalM235iR]

So when I add an upgraded IC won't that make the fuel pressure issues worse, since the colder, denser IA will require more fuel?

I'm likely going for an IC upgrade and considering my options for an upgraded HPFP, however, I don't want to add the FP and still have the same problems. Really would like to solve this problem short of throwing more parts at it.

I'm not trying to chase big HP/TQ numbers, just looking to run a stage 2 map on pump CA 91 and completely happy to run the appropriate CA fuel map to do it. Surely I can't be the only N55 guy in CA having trouble with these maps on a nearly stock car.

[n55david]

Originally Posted by SoCalE90

So when I add an upgraded IC won't that make the fuel pressure issues worse, since the colder, denser IA will require more fuel?

I'm likely going for an IC upgrade and considering my options for an upgraded HPFP, however, I don't want to add the FP and still have the same problems. Really would like to solve this problem short of throwing more parts at it.

I'm not trying to chase big HP/TQ numbers, just looking to run a stage 2 map on pump CA 91 and completely happy to run the appropriate CA fuel map to do it. Surely I can't be the only N55 guy in CA having trouble with these maps on a nearly stock car.

doesn't matter. your iats are nuts and you need an ic regardless

[thejeremyman9]

Originally Posted by SoCalE90

So when I add an upgraded IC won't that make the fuel pressure issues worse, since the colder, denser IA will require more fuel?

I'm likely going for an IC upgrade and considering my options for an upgraded HPFP, however, I don't want to add the FP and still have the same problems. Really would like to solve this problem short of throwing more parts at it.

I'm not trying to chase big HP/TQ numbers, just looking to run a stage 2 map on pump CA 91 and completely happy to run the appropriate CA fuel map to do it. Surely I can't be the only N55 guy in CA having trouble with these maps on a nearly stock car.

1. Technically yes, but that's not a reason not to upgrade the IC. The problem needs to be solved with or without an IC, and not running one is frankly kindof dangerous.

2. Generally yes the approach of solving the problem first makes sense, but i wouldnt drive the car hard before the IC upgrade.

3. 100% agree with not chasing big numbers, but if you plan to drive the car on track you need supporting mods. If you are going BM3 stage 2 that would be at a minimum IC, CP, and DP. If you go upgraded HPFP you can run ethanol and the 2+ map.

Actually, you the fueling issue you have is very rare. Maybe one other person had a similar issue i can recall in the past year and IIRC they needed a new HPFP. Not saying that is what you need, but your situation is an anomaly.

[SoCalM235iR]

I have a stepped IC on the way. Already have the CP and DP, and both fuel pumps, all injectors and pre cat O2 have been changed in the last 10K miles chasing this issue. I had two fuel injector failures back when I was running the JB4 so I'm considering the FI's as consumables like plugs and coils.

I'm okay with dropping $1100+ on an aftermarket FP if that will allow a stage 2 map safely on track. If I can blend in a bit of E85 that would be great as well.

I'm leaning towards the Dorch Stage 1 FP. Any feedback on that choice is appreciated. I have no plans for a big turbo or anything else.

Has anyone successfully used the HDP6 (Stock B58TU) on an N55?

[thejeremyman9]

Originally Posted by SoCalE90

I have a stepped IC on the way. Already have the CP and DP, and both fuel pumps, all injectors and pre cat O2 have been changed in the last 10K miles chasing this issue. I had two fuel injector failures back when I was running the JB4 so I'm considering the FI's as consumables like plugs and coils.

I'm okay with dropping $1100+ on an aftermarket FP if that will allow a stage 2 map safely on track. If I can blend in a bit of E85 that would be great as well.

I'm leaning towards the Dorch Stage 1 FP. Any feedback on that choice is appreciated. I have no plans for a big turbo or anything else.

Has anyone successfully used the HDP6 (Stock B58TU) on an N55?

Thing is, stock HPFP should be more than adequate for what you are doing. So something doesn't add up. Would suck to replace the HPFP and still have the issue. The only other piece of the puzzle that very little is known about is the HPFP pressure control system.

Dorch is the most common option now and probably the one i would say go with if you are going to do it. There are a couple of threads on retrofitting the B58 pump. IIRC one version will bolt in, but you are not supposed to run it because it doesn't fit correctly on the lobe or something (i would have to look up exact reason).

[SoCalM235iR]

Originally Posted by thejeremyman9

Thing is, stock HPFP should be more than adequate for what you are doing. So something doesn't add up. Would suck to replace the HPFP and still have the issue. The only other piece of the puzzle that very little is known about is the HPFP pressure control system...
.

This is EXACTLY my concern. What if the system adapts to the new pump and does the same thing and requests all this fuel and crashes the fuel pressure like it does now.

Recall that immediately after I flash a new or previous map, the car runs great and doesn't crash the fuel pressure for 70-150 miles. I assume adaptions occur and that is the problem.

With my latest BM3 map email:

Halim @BM3 commented:

Seems like it goes into some sort of open-loop where it just injects tons of fuel without correction.

I set minimal AFR now on this dynomap, let’s see if it helps.

[thejeremyman9]

Originally Posted by SoCalE90

This is EXACTLY my concern. What if the system adapts to the new pump and does the same thing and requests all this fuel and crashes the fuel pressure like it does now.

Recall that immediately after I flash a new or previous map, the car runs great and doesn't crash the fuel pressure for 70-150 miles. I assume adaptions occur and that is the problem.

With my latest BM3 map email:

Halim @BM3 commented:

Seems like it goes into some sort of open-loop where it just injects tons of fuel without correction.

I set minimal AFR now on this dynomap, let’s see if it helps.

Yeah, actually i see that now, AFRs going to the 10s. The other thing that stands out is LTFTs are +14%. That could be part of the problem and why clearing adapations fixes it.

[SoCalM235iR]

Yes I noticed the LTFT's going crazy as soon as I load the tune. As high as +17. They almost sit at 0 on the stock tune.

[thejeremyman9]

Originally Posted by SoCalE90

Yes I noticed the LTFT's going crazy as soon as I load the tune. As high as +17. They almost sit at 0 on the stock tune.

Hmm do you have any shadow codes on either bm3 tune or on stock? Its like the car is fighting LTFTs... the LTFTs are way positive then STFTs negative to compensate pulling all that fuel back out. Both shouldn be much closer to zero. I wish there was a way for you to try MHD and see if the same thing happens

Edit: Also i wonder if BM3 can jsut disable LTFTs in the tune? and see what happens

[SoCalM235iR]

I have the latest BM3 tune with just under 100 miles. I did a full scan of all 28 computers and found these codes. The ECU codes I assume are tuner codes and normal? However, this could account for the crazy LTFT's . I have no CEL.

I've too thought about trying another tuner just to confirm that it's not the car. I'm hesitant to drop the money on a fuel pump knowing that the car should not require that to run a stage 2 tune.

[thejeremyman9]

Air mass is a "tuner code" but i don't know what ZGM one is. If you never plan to mod the car enough to run a upgraded HPFP, maybe MHD is worth testing... worst case you can resell your BM3 to recoup most the cost? Just a thought

[SoCalM235iR]

I just shared those codes with BM3. We'll see if they have anything to add. I have considered what you suggest, getting the MHD tune to test, but if I end up at the same place I'll be back to looking at aftermarket HPFPs

Somehow I was expecting an easy solution...LOL

[thejeremyman9]

Originally Posted by SoCalE90

I just shared those codes with BM3. We'll see if they have anything to add. I have considered what you suggest, getting the MHD tune to test, but if I end up at the same place I'll be back to looking at aftermarket HPFPs

Somehow I was expecting an easy solution...LOL

After seeing what BM3 said and looking back at the logs i am pretty convinced upgrading the HPFP is a workaround and would not fix the actual problem. Sure, you might not lose fuel pressure, but the problem is with there being too much fuel commanded (which is why AFRs dip into the 10s). Even if upgrading the pump makes it not crash that is not good.

Two other things that come to mind are the MAF and primary O2. I believe both are used to derive LTFTs that are learned over time. So i wonder if your MAF or primary O2 are reading incorrectly contributing to such high LTFTs. Have you tried driving without the MAF plugged in to see if the problem still happens?

[SoCalM235iR]

Yeah just increasing the headroom in the fuel system is not going to address the AFR's going into the 10's , which is likely a programming issue and adding all the fuel when it's really not required will be another problem. Right now the fuel system can't deliver the requested fuel so the problem isn't what it could be if I upgrade the HPFP?

I have not tried running without the MAF. I did replace the primary O2 after replacing both pumps and all the injectors, so that is a new one.

I'm going to put some more miles on this new tune and send BM3 the logs as well as post them here. Right now this tune seems to be holding fuel pressure above 2000 psi, however, the max boost I'm seeing is only 14 or 15 PSI, which is disappointing.

After that, I will install the stage 2 ACN tune and try running it with the MAF disconnected. Thanks for the suggestion.

[LA1Z24]

I have a theory that BM3 is overdriving the HPFP regulator driver in the DME, and rather than smoking the circuit, the ECM goes into a safety mode by cutting down the command to the HPFP. Unfortunately the location of the HPFP makes it difficult to put an amp clamp on the wires to see if the actual command signal falls back, while the command in the datalog is still calling for 2400psi.

[thejeremyman9]

Originally Posted by LA1Z24

I have a theory that BM3 is overdriving the HPFP regulator driver in the DME, and rather than smoking the circuit, the ECM goes into a safety mode by cutting down the command to the HPFP. Unfortunately the location of the HPFP makes it difficult to put an amp clamp on the wires to see if the actual command signal falls back, while the command in the datalog is still calling for 2400psi.

If i understand what you are saying correctly, his problem is the opposite, because the car is actually delivering too much fuel. So it's not just that he has a fuel pressure drop when he shouldnt, but it looks like the fuel pressure drop is "real" in the sense that the pressure drops because the pump can't keep up with the actual amount of fuel supplied. The thing is we don't know why the tune is telling it to supply that much fuel (except for strange fuel trims)

It seems like you are saying the DME might be telling the HPFP to supply less even if the log says the target is still say 2400. But if that were true in his case, he wouldnt have the fuel trim issue and the super rich AFR that corresponds with the pressure drop.

[designatedposter]

fuel crash after gear shifts, which is when the STFT is not actively pulling back fuel (you can see STFT=1 for a few hundred RPM after each shift).

seems to me your fuel system is supplying more fuel than anticipated and relies on STFT to pull back approximately 15% fuel (STFT=.85).

maybe this can be fixed by simple adjustment to fuel scalar or recalibrate injector.

has ptf offered any help?

**just saw that halim did something with AFR to help... but i don't see how that can help. regardless of what the AFR target is set to, your fuel system is going to supply approx 15% more fuel than needed. the big question is why is your fuel system pushing more fuel than the normal, and the bandaid fix is to adjust fuel scalars.. my 2c

[thejeremyman9]

Originally Posted by designatedposter

fuel crash after gear shifts, which is when the STFT is not actively pulling back fuel (you can see STFT=1 for a few hundred RPM after each shift).

seems to me your fuel system is supplying more fuel than anticipated and relies on STFT to pull back approximately 15% fuel (STFT=.85).

maybe this can be fixed by simple adjustment to fuel scalar or recalibrate injector.

has ptf offered any help?

**just saw that halim did something with AFR to help... but i don't see how that can help. regardless of what the AFR target is set to, your fuel system is going to supply approx 15% more fuel than needed. the big question is why is your fuel system pushing more fuel than the normal, and the bandaid fix is to adjust fuel scalars.. my 2c

His LTFTs are +14%. So the problem seems to be fundamentally the LTFTs. Basically, he should have ~0% fuel trims, but for some reason LTFTs are going +14, which then makes the car super rich when STFTs are 0 (i.e., on shift, which is normal, as they take a second to respond), then STFTs need to correct by pulling ~15% fuel.

So his STFTs are basically fighting LTFTs, and car is rich when STFTs are not active.