DW400 Fuel Pressure Dropping During WOT - Whipple Stage 2

[WildHorse]

I've seen pumps that'll try to suck the sock inside out, collapse fuel filters (yes I know there isn't one on a s550, just sayin), low quality fuel hoses collapse, a myriad of things.

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[NGOT8R]

Could really low fuel levels cause the low pressure readings at WOT if the fuel is sloshing around and the pump is sucking air?

 

[WildHorse]

Could really low fuel levels cause the low pressure readings at WOT if the fuel is sloshing around and the pump is sucking air?

Easiest way to would be to check the STFT in the logs.

 

[Vert]

Could really low fuel levels cause the low pressure readings at WOT if the fuel is sloshing around and the pump is sucking air?

If I was you, I wouldn't go WOT if you have low fuel. Low fuel levels can starve the fuel pump and you could go lean which can lead to motor destruction.

 

[Face]

I'm having a similar problem on my centri-boosted 2019, however I am still on the stock pump but with a BAP. My lift pump fuel pressure drops to about 52-55psi on 93. I waiting on the DW400 pump to arrive and install to see if it solves my issues. If not, I'll run the BAP with the DW400 as Engineer Mike has suggested.

Out of curiosity, are you seeing any codes associated with this issue? I'm getting two codes that I clear but they always return. A P2BEE (Bank 2) and P2BEC (Bank 1) which are fuel system (A) too lean. The car runs fine otherwise, STFT's are good as is afr's. Fuel pressure drops to 40psi on the hit, then recovers and drops again as rpm's climb.

I'm leaning towards just trying the BAP with the DW and seeing what happens. But to your second question, no issues, no codes, etc with the car at all- Lund actually was impressed with how 'happy' the car seems otherwise, go figure lol.

Are you having any startup issues? I have the stage 2 Whipple kit with the DW 400. The fuel pump works for me during wot and normal driving. But Lund told me there was no check valve so the car starts and sometime it shuts off before I have to try and start it again.

None, but then again the car has only seen a few dyno sessions after the install and no real street driving.

I've seen pumps that'll try to suck the sock inside out, collapse fuel filters (yes I know there isn't one on a s550, just sayin), low quality fuel hoses collapse, a myriad of things.

We're using the 'fluted' hard plastic lines that DW included with the kit- so no issues there.

 

[CJJon]

Prime example of going FI and thinking one can get away with a stock fuel set up. Sorry OP that you are having issues. IMO, the only solution is a return system.

Lean = Boom

 

[Face]

Prime example of going FI and thinking one can get away with a stock fuel set up. Sorry OP that you are having issues. IMO, the only solution is a return system.

Lean = Boom

LOL- its not a 'stock fuel setup' its the upgraded fueling components that Whipple deems safe to run their stage 2 setup- and hundreds, if not thousands do without issue. This case is an outlier, as Lund has pointed out and the reasoning behind this troubleshooting thread.

 

[CJJon]

LOL- its not a 'stock fuel setup' its the upgraded fueling components that Whipple deems safe to run their stage 2 setup- and hundreds, if not thousands do without issue. This case is an outlier, as Lund has pointed out and the reasoning behind this troubleshooting thread.

But you are the unlucky one with problems. When I wrote stock fuel set up I kinda felt someone would take exception there. Poorly worded on my part. I should have said single pump, non-return style.

Am I correct you are not using a BAP?

Again, be careful. Lean = Boom

 

[CJJon]

What injectors you running, OP?

 

[Face]

What injectors you running, OP?

56LB- but its not an issue with the injectors- the issue is with the HLFP which is causing a drop in pressure in the upper RPM range, also affecting the high pressure rail too.

But you are the unlucky one with problems. When I wrote stock fuel set up I kinda felt someone would take exception there. Poorly worded on my part. I should have said single pump, non-return style.

Am I correct you are not using a BAP?

Again, be careful. Lean = Boom

All good- no BAP, yet. But will probably try one.

 

[engineermike]

The gen3 fuel system is very "smart", if you will. Unlike the gen2, the gen 3 measures and controls the lift pump pressure to a pressure specified on a table. Lower loads and speeds command less pressure. You can monitor lift pump pressure desired, measured, and lift pump duty cycle. If you are achieving the commanded fuel pressure at a duty cycle less than 49% at max load, then your stock single pumps system is completely within bounds. This control system also works with the DW400 with no changes and boost-a-pump with tuning tweaks.

The stock strategy also uses the actual fuel pressure to calculate actual injector flow, unlike prior generation coyotes. If the pressure goes low, it automatically modifies injector PW to achieve the desired flow. Note the OP's flow should have dropped 20% at the measured fuel pressure, but lambda was still good. Furthermore, if activated in the tune, when the PCM senses that the fuel system just can't keep up, even at max lift pump DC and max injector PW, it will cut the throttle to keep lambda in check. Ford implemented some of the ecoboost PCM strategy to make it really hard to run this one lean.

The Roush Phase 2 cars run 12 psi boost on the stock pump with no BAP. Some of them trigger "insufficient fuel flow" codes and require new pumps, yet very few if any have had failures due to lean running.

 

[NGOT8R]

If I was you, I wouldn't go WOT if you have low fuel. Low fuel levels can starve the fuel pump and you could go lean which can lead to motor destruction.

Oh, I hear ya. I don’t even trust going WOT on a 1/4 tank. I would rather carry the extra weight in fuel than risk sucking air and leaning out.

 

[TEXAS HEAT]

The gen3 fuel system is very "smart", if you will. Unlike the gen2, the gen 3 measures and controls the lift pump pressure to a pressure specified on a table. Lower loads and speeds command less pressure. You can monitor lift pump pressure desired, measured, and lift pump duty cycle. If you are achieving the commanded fuel pressure at a duty cycle less than 49% at max load, then your stock single pumps system is completely within bounds. This control system also works with the DW400 with no changes and boost-a-pump with tuning tweaks.

What are the tuning changes required when running the BAP?

The stock strategy also uses the actual fuel pressure to calculate actual injector flow, unlike prior generation coyotes. If the pressure goes low, it automatically modifies injector PW to achieve the desired flow. Note the OP's flow should have dropped 20% at the measured fuel pressure, but lambda was still good. Furthermore, if activated in the tune, when the PCM senses that the fuel system just can't keep up, even at max lift pump DC and max injector PW, it will cut the throttle to keep lambda in check. Ford implemented some of the ecoboost PCM strategy to make it really hard to run this one lean.

The Roush Phase 2 cars run 12 psi boost on the stock pump with no BAP. Some of them trigger "insufficient fuel flow" codes and require new pumps, yet very few if any have had failures due to lean running.

So it seems that my P2BEE and P2BEC codes are unrelated to the lift pump pressure drop issues that I am experiencing.

 

[engineermike]

What are the tuning changes required when running the BAP?

The lift pressure is supposed to drop to 55 psi at idle iirc. I found that with an 18v bap and no tuning changes it would run at 73 psi all the time because the needed dc was below the min dc. Reducing min dc in the tune made no difference. Changing the pump voltage table made no difference. I am told that most tuners say don’t worry and let it run at 73 psi all the time. Btw, the in-tank relief valve is set at 73. I finally found success in modifying the fuel pump pwm slope. I think more time spent adjusting slope AND offset could improve control further. It is on a PID control loop but the slope (and offset) has to be modified to get it within control bounds.

 

[Face]

The gen3 fuel system is very "smart", if you will. Unlike the gen2, the gen 3 measures and controls the lift pump pressure to a pressure specified on a table. Lower loads and speeds command less pressure. You can monitor lift pump pressure desired, measured, and lift pump duty cycle. If you are achieving the commanded fuel pressure at a duty cycle less than 49% at max load, then your stock single pumps system is completely within bounds. This control system also works with the DW400 with no changes and boost-a-pump with tuning tweaks.

The stock strategy also uses the actual fuel pressure to calculate actual injector flow, unlike prior generation coyotes. If the pressure goes low, it automatically modifies injector PW to achieve the desired flow. Note the OP's flow should have dropped 20% at the measured fuel pressure, but lambda was still good. Furthermore, if activated in the tune, when the PCM senses that the fuel system just can't keep up, even at max lift pump DC and max injector PW, it will cut the throttle to keep lambda in check. Ford implemented some of the ecoboost PCM strategy to make it really hard to run this one lean.

The Roush Phase 2 cars run 12 psi boost on the stock pump with no BAP. Some of them trigger "insufficient fuel flow" codes and require new pumps, yet very few if any have had failures due to lean running.

The lift pressure is supposed to drop to 55 psi at idle iirc. I found that with an 18v bap and no tuning changes it would run at 73 psi all the time because the needed dc was below the min dc. Reducing min dc in the tune made no difference. Changing the pump voltage table made no difference. I am told that most tuners say don’t worry and let it run at 73 psi all the time. Btw, the in-tank relief valve is set at 73. I finally found success in modifying the fuel pump pwm slope. I think more time spent adjusting slope AND offset could improve control further. It is on a PID control loop but the slope (and offset) has to be modified to get it within control bounds.

Thanks for the knowledge here Mike, greatly appreciated.

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