[tawfeeqh]

Hi guys

Few days ago I installed new HPFP, Index 12 injectors, NGK plugs and Eldor coils so thought it would be a good time log a pull from 3000rpm to redline in 3rd gear.

Logs below - In one of the logs, I'm finding a strange drop in LPFP to 50 psi accompanied with a drop in rail pressure to 800psi. Exactly 1min later I do another pull and in this one LPFP pressure remains steady between 70-80 psi and rail pressure remains stable and does not drop below 2000 psi (nice clean log).

I am running Fuelit stage 3 pumps, PI, AIC6 controller, hobb switch and 100% e85.

4/08/2017 at 2.03pm - Bad Log

http://www.datazap.me/u/tawfeeqh/lpf...=10&zoom=6-153

4/08/2017 at 2.04pm - Clean Log

http://www.datazap.me/u/tawfeeqh/lfp...13&zoom=25-178

Fuel trims in both look fine and there is zero timing corrections.

I am going to send steve@fuelit an e-mail to see what he says but thought I'd also post here in case anyone has any ideas. Maybe i'll begin by changing out the hobb switch

Tawfeeq

[vtl]

In the first log the boost drops and looks like it falls below the threshold of the hobbs switch, turning off your pump

Second log boost stays stable and all is good.

[MJ80.]

Dude ive been having similar thoughts myself, i took a log the other night to check my lpfp and hpfp values as im still on stock lpfp running e40 and they seemed just within spec. But then compared to another e40 log from a month or two ago and the hpfp is majorly down on psi.

This is the log from last night.

http://www.datazap.me/u/mj80/log-150...ata=3-12-20-21

And this is the month or so ago, both running the same tune.


http://www.datazap.me/u/mj80/log-149...a=3-5-12-20-21

[tawfeeqh]

Originally Posted by vtl

In the first log the boost drops and looks like it falls below the threshold of the hobbs switch, turning off your pump

Second log boost stays stable and all is good.

Thanks Vince - will log target boost and as you suggested look for any boost leaks

[tawfeeqh]

Originally Posted by MJ80.

Dude ive been having similar thoughts myself, i took a log the other night to check my lpfp and hpfp values as im still on stock lpfp running e40 and they seemed just within spec. But then compared to another e40 log from a month or two ago and the hpfp is majorly down on psi.

This is the log from last night.

http://www.datazap.me/u/mj80/log-150...ata=3-12-20-21

And this is the month or so ago, both running the same tune.


http://www.datazap.me/u/mj80/log-149...a=3-5-12-20-21

hey mate

are you running stage 2 pumps? im running stage 3 pumps which are the dual walbro setup and the secondary pump is engaged through a mechanical hobb switch. My rail pressure is dropping because my lpfp is dropping.

Your low fuel pressure is dropping to around 40 in the log your rail pressure drops to under 1000. If you dont have a stage 2 pump this is kind of expected, if you do than thats strange

[MJ80.]

It doesn't drop below 1200 during the pull. But anyway thats not the point, im aware that lower than 1500 is too low. Thats the point im making, why is the hpfp struggling in that old log, yet in the new log its within spec at 1600.

And like i said in my post on stock lpfp.

[vtl]

You should be running an upgraded LPFP with ethanol mixes. Sure some people say you can get away without it, but depending on the conditions you will need one. Certain conditions the fuel demand will be higher, not to mention you probably don't have an ethanol analyser so its definitely smarter to have a lot of margin in your fuel system.

[tawfeeqh]

Originally Posted by MJ80.

It doesn't drop below 1200 during the pull. But anyway thats not the point, im aware that lower than 1500 is too low. Thats the point im making, why is the hpfp struggling in that old log, yet in the new log its within spec at 1600.

And like i said in my post on stock lpfp.

Oh okay sorry didnt read your thread properly. If you're on stock pump then as Vince has said you should probably upgrade your lpfp if you are running ethanol blends.

I was just eye balling and thought it was dipping to 1000, but yeh its still over 1000 at around 1200

[tawfeeqh]

vtl

I plotted both logs together and based on this looks like maybe the secondary LPFP pump is turning on at 20 psi boost as the LPFP spikes to over 90 PSI. In the bad log the boost drops under 20 psi and then moments after the LPFP drops drastically to 50 psi.

If I run the mechanical hobb switch I could adjust the on/off threshold to perhaps keep it ON over 18 psi not 20. But in any case this is hardly accurate

But the route of the problem is boost dropping off quickly. Could be a boost leak causing it.

Points to what you were saying above

[MJ80.]

Originally Posted by vtl

You should be running an upgraded LPFP with ethanol mixes. Sure some people say you can get away without it, but depending on the conditions you will need one. Certain conditions the fuel demand will be higher, not to mention you probably don't have an ethanol analyser so its definitely smarter to have a lot of margin in your fuel system.

Yeah i know it would be nice to have one and its next on the list, i was logging to see if it wasnt coping and if so i would have ordered a pump, but everything is above board atm, just and if it aint broke ? Using the united 107 which is pretty much bang on its % so shouldn't be an issue, trims arent hitting 34 so seems to be loads of margin left.

But you certainly can get away with it, this is e40 so its as far as id reccomend pushing stock setup and everyones cars different, some wont handle it some will.

Stage 2 pump is on the list.

[Coupes33]

Originally Posted by tawfeeqh

vtl

I plotted both logs together and based on this looks like maybe the secondary LPFP pump is turning on at 20 psi boost as the LPFP spikes to over 90 PSI. In the bad log the boost drops under 20 psi and then moments after the LPFP drops drastically to 50 psi.

If I run the mechanical hobb switch I could adjust the on/off threshold to perhaps keep it ON over 18 psi not 20. But in any case this is hardly accurate

But the route of the problem is boost dropping off quickly. Could be a boost leak causing it.

Points to what you were saying above

If it was a boost leak, you would think it would have shown up in the second log. I had a similar thing happen to me when I did a datalog of a tune with higher boost levels which required installing a BMS Maxboost onto the TMAP sensor. We put it down to the PI not cutting in which overloaded the HPFP. I wasn't logging the LPFP so I can't see what it was doing. Removal of the maxboost and changing the tuned fixed the issue for me. Steve (Fuel-it) said the PI software would need tuning to correct the issue related to the other high boost tune. With regards the Hobb switch for the Stage3 LPFP, I have mine set at 15psi.

http://www.datazap.me/u/coupes44/dat...0&data=2-21-22

[tawfeeqh]

Originally Posted by Coupes33

If it was a boost leak, you would think it would have shown up in the second log. I had a similar thing happen to me when I did a datalog of a tune with higher boost levels which required installing a BMS Maxboost onto the TMAP sensor. We put it down to the PI not cutting in which overloaded the HPFP. I wasn't logging the LPFP so I can't see what it was doing. Removal of the maxboost and changing the tuned fixed the issue for me. Steve (Fuel-it) said the PI software would need tuning to correct the issue related to the other high boost tune. With regards the Hobb switch for the Stage3 LPFP, I have mine set at 15psi.

http://www.datazap.me/u/coupes44/dat...0&data=2-21-22

Yeh its a bit of a confusing one because as you can see i did two logs 1min apart and it one the lpfp and rail pressure stay in check and in the other the lpfp drops and this also causes the rail pressure to drop as the secondary pump supplying fuel to the PI has switched off.

Thats the only way I can comprehend whats going on. Its hard to diagnose because it doesn't happen all the time, but its clear it happens when boost peaks over 20 psi then drops below it. Perhaps I need to lower hobb switch trigger for secondary lpfp to 15-17 psi

In terms software setup for PI im running MHD maxboost and the hobb switch. Will do a bit more reading on the forums to see what i can find

[tawfeeqh]

Edit: Looking at my logs again and I think the secondary pumps do turn on at 15psi because thats when the volatility of the LPFP pressure increases. I wonder why then the secondary pump turns off pre-maturely given that even on the bad log above, the boost remains over 15 psi.

I have sent steve@fuelit an email to see what he says. I just want to know what the issue is whether its the stage 3 pump, hob switch, tune etc