I have an lbz pump on my lb7, tony tunes it. The pump was right from the dealer 2 weeks ago. I know that doesnt mean its always good. Injectors are brand new as well. The rail pressure is great just driving around normal and at wide open throttle but when I let off to slow down, from 50mph until I stop, the truck has a lope. Tony is aware of the lbz pump and the tune is set up for it. I had the lift pump pressure turned up slightly but just turned it down to 10psi. I read the lb7 ficms dont like a lot of fuel pressure which is why I turned it down. When you are coasting to a stop, the rail pressure builds up to 80-90mpa when it is only commanding 35mpa. Any other ideas if maybe the regulator is sticking or if anything else can cause it? Thanks in advance...
rail pressure builds as i slow down with lope
- Thread starter onebaddmaxxx
- Start date
well I just unplugged the airdog completely and it stopped and sounds good slowing down, and is down at 35-40mpa slowing down. My next question is, if my airdog pressure is down at 10psi at idle, which i think is the preset pressure, why is it doing it? Iv installed many trucks that had the same set up and never loped. Im not going to turn my lift pump down to the point where its not functional. It defys the purpose of having it. If there is no fix for why it does it, then I guess I will put it on a switch and only power it when im racing.
On a side note, iv heard the lb7 ficms dont like pressure and some can be jumpy. But i dont feel like relocatting it to run it dry just to fix this prob. Is there any other reason it will do it or is a switch my only option?
On a side note, iv heard the lb7 ficms dont like pressure and some can be jumpy. But i dont feel like relocatting it to run it dry just to fix this prob. Is there any other reason it will do it or is a switch my only option?
Mine does this after it's warmed up and I've bypassed the ficm a long time ago. I have no idea how long it's done it as I never noticed it till driving around without the radio one day and never really looked into it. Be interested to see what you find.
The LB7's have no problem with high lift pump pressures if you tune for it. Tell your tuner what is happening, and that you have a lift pump above default pressure, and they should be able to dial it out.
Mine did the same thing when I cranked the pressure up. You go into the regulator current table and add 50-200 mA to the bottom few cells. The exact amount will depend on your tune, lift pump pressure, etc. That will keep your rail where it should be. :thumb:
Mine did the same thing when I cranked the pressure up. You go into the regulator current table and add 50-200 mA to the bottom few cells. The exact amount will depend on your tune, lift pump pressure, etc. That will keep your rail where it should be. :thumb:
Sorry, totally forgot about this until this morning 
You will want to add current to the bottom 2 to 4 cells of {B1010}, depending on what the main fuel flow rate is when you run over the desired rail pressure. You can log FUELQ_MAIN_DMA with EFILive to see exactly where you need to change the table.
I attached a screenshot of my table so you can see what I mean. Notice the bottom 4 values (0 - 3000 mm3 per second) are at a steeper angle than the main part? That is what I mean.
I wouldn't copy my table exactly. Mine is set up for a LBZ regulator on a LB7 pump with 60% over injectors. You just want to add some current to your current values to get rid of the overpressure.
Kappa9012 makes a good point: have you put a fuel pressure gauge on the airdog? It could be malfunctioning.
You will want to add current to the bottom 2 to 4 cells of {B1010}, depending on what the main fuel flow rate is when you run over the desired rail pressure. You can log FUELQ_MAIN_DMA with EFILive to see exactly where you need to change the table.
I attached a screenshot of my table so you can see what I mean. Notice the bottom 4 values (0 - 3000 mm3 per second) are at a steeper angle than the main part? That is what I mean.
I wouldn't copy my table exactly. Mine is set up for a LBZ regulator on a LB7 pump with 60% over injectors. You just want to add some current to your current values to get rid of the overpressure.
Kappa9012 makes a good point: have you put a fuel pressure gauge on the airdog? It could be malfunctioning.
Attachments
honestly, i lowered my airdog down to 6-7psi at idle and the truck is running its balls off right now with no lope slowing down. If i turned the airdog back up to 10-12 and have this table adjusted will i pick up and power/time at track? If so ill log it and adjust, if not, ill leave it alone
If it runs fine and holds rail at WOT, leave the pressure alone. No need for more.