09' Mustang, fuel pressure rises as vehicle runs longer???

[undergroundak]

Hello,


I'm currently working on a 2009 Mustang GT running a whipple and GT500 pumps/controllers. I tuned the vehicle in the spring with no issues. He returned for a re-tune for a different maf, headers and he added a VMP tuning duel fuel pump voltage booster. The VMP booster is the only fuel system change.
When I initially start the car I am running approx 30PSI at idle with a commanded 12% pump dc. The longer I run the car on the dyno the higher the pressure is at idle and part throttle. After about 20 minutes my commanded dc for the pump is 18% and the pressure is almost 50PSI at idle. I assume I'm missing something as I've never ran into this before but I have not run the VMP booster either.
Any input would be great.

Thanks!
NickUSE ME BASE-9.hpt

[jchambers]

Fuel pressure due to inferred rail temperature. There are tables to allow adjustment for this.

[undergroundak]

I do not have a "Fuel pressure due to inferred rail temperature". The closest table I have found is [ECM] 43010 - Ambient Rail Temp Time Constant vs. Fuel Flow:. The definition of the table was not clear on what adjustments would result in. Also the pressure increase parallels intake temp not ambient and there are no other tables within the fuel system to adjust dc based on intake temps or rail temps aside from 43010. I prefer HP's software but I'm used to SCT that has all pid's covered so I am limited o what I can see. I'll adjust 43010 and see if I can get steady rail pressure and may e-mail support to see if there are missing tables that I need.

Thanks!
Nick

[jchambers]

Fuel Pressure ACT.JPG

Don't have HPT open to see what its actually called in HPT, but would be in the returnless fuel system category.

[BNA]

43005 - Fuel Pump Injector Pressure Drop Adder vs. Ambient Temp: This adds to the injector pressure drop in relation to ambient air temperature.

What are IAT at? IAT sensor should be located after intercooler. The tune file is locked BTW

[BNA]

43005 - Fuel Pump Injector Pressure Drop Adder vs. Ambient Temp: This adds to the injector pressure drop in relation to ambient air temperature.

What are IAT's at? IAT sensor should be located after intercooler. The tune file is locked BTW

[undergroundak]

Looks like [ECM] 43010 - Ambient Rail Temp Time Constant vs. Fuel Flow is actually intake temp and not ambient. I adjusted this table and the pressure has stabilized. I guess even though it says "ambient" it appears to make changes based on intake temps as the pressure would rise as intake temps rose and actual ambient were steady according to logging info.
This had me chasing my tail for a while as my fueling would gradually go berserk. But it looks like its sorted now so I'll be back on the dyno soon.

Thanks for the input!
Nick

[BNA]

SCT shows this table as Rail Temp Time Constant. Does not say anything about Ambient temp. What did you set your values to?

[ElecTech]

Looks like [ECM] 43010 - Ambient Rail Temp Time Constant vs. Fuel Flow is actually intake temp and not ambient. I adjusted this table and the pressure has stabilized. I guess even though it says "ambient" it appears to make changes based on intake temps as the pressure would rise as intake temps rose and actual ambient were steady according to logging info.
This had me chasing my tail for a while as my fueling would gradually go berserk. But it looks like its sorted now so I'll be back on the dyno soon.

Thanks for the input!
Nick

The labeling would suggest that the ambient rail temp is affected by the intake manifold temp. Which makes sense in a heat transfer sort of way. It might be a little misleading, but not really because the table is accounting for the change in fuel rail ambient temps, they just happen to be related to the effect of the intake heat. That's how I see it.