ActiveMonkey
11-09-2023, 01:53 PM
Hey Folks,
I've been having intermittent power surging/hesitation under WOT while running IE Single Pulley E85 tune for ~10 months and would like to get your thoughts. I feel its worth noting, the power surging/hesitation issue is nonexistent on the 91 octane file. The 91 file runs great, the car is just slower than when I run the E85 file.
My understanding of the way the car handles fuel pressure is the following: The ECU requests a specific pressure low pressure fuel pressure. The ECU then ramps up the duty cycle of the LPFP making it pump more fuel and build pressure. The cars first layer of control is the fuel pressure regulator on the in tank fuel pump assembly which begins to open up at 5.5 bar and dumps excess fuel bank into the tank. If fuel pressure still gets too high according to the low pressure fuel pressure sensor located under the supercharger on the low pressure fuel rail, the ECU will reduce the LPFP duty cycle to bring down the low pressure fuel pressure. Aside from the below listed parts (which have all been replaced trying to trouble shoot the issue), what could cause a drop in the low pressure fuel pressure or intermittent power surging/hesitation under WOT?
LPFP
LPFP control module
Low pressure fuel pressure sensor
High pressure fuel pressure sensor
HPFP
Logs showing no issue
Log 1: https://datazap.me/u/activemonkey/e70-4th-gear-log?log=0&data=1-21
Log 2: https://datazap.me/u/activemonkey/e70-4th-gear-log-2?log=0&data=13-19
Logs showing issue
Log 3: https://datazap.me/u/activemonkey/e70-power-surging?log=0&data=10-16
Log 4: https://datazap.me/u/activemonkey/e70-power-surging-accidently-hit-kick-down?log=0&data=4-21
*Accidentally hit the kick down on log 4.
After a few file revision from IE, the power surging/hesitation is still intermittent and the only code that pops up is the P025b Fuel Pump Module 'A' Control Circuit Range/Performance.
BACKSTORY
TLDR; Replaced nearly all fuel components and the problem still persists.
LONG VERSION:
Below is a not so brief overview/history.
January 23 I am getting power surging and p310b, p0089 and p025b so I data log, see low pressure from the LPFP and replace LPFP with new pump assembly from Audi. Surging goes away for the most part, but codes are persistent. (New LPFP Pump #1)
April-May 23 Power surging returns. I submit logs to IE, they says the LPFP is bad and needs to be replaced. I replace with another new LPFP from audi. Surging goes away for the most part, but codes are persistent. (New LPFP Pump #2)
June 23 I replace HPFP with new from audi to see if this fixes the surging/hesitation issue or the p310b, p0089 and p025b codes. It does not.
June Sep 23 In an attempt to resolve the codes and power surging/hesitation issue I replace all coils twice, new upstream and downstream O2 sensors, bypass valve and LPFP control module. No change.
Oct 23 - I install an AutoTech HPFP Piston so see if that has any impact. Oh boy did it! Instead of just power surging the car would misfire, EPC light and hide a cylinder. It really seems like the LPFP just cannot keep up. I replace the upgraded HPFP with stock HPFP from Audi and Im back to power surging and p310b, p0089 and p025b. When it does run correctly it does run very will. IE makes revision to E85 File (V1.05) with new fuel set points. Codes p310b, p0089 go away but p025b remains along with intermittent surging/hesitation issue.
10/23/23 Seeing logs with low LPFP AV I buy another LPFP from audi and install it. No change. LPFP values intermittently in the ~3 bar range causing surging/hesitation. To rule out other hardware, I remove, test and clean the port injectors, replace the direct injectors, and the high pressure and low pressure fuel pressure sensors located under the supercharger. While everything is out, I blow out the fuel lines to confirm no debris or obstructions in the lines. No change, LPFP values intermittently in the ~3 bar range causing surging/hesitation. Dealer doesnt want to warranty the pump but accepts return. (New LPFP Pump #3)
10/28/23 I install another new LPFP from a different vendor though the pump is still Continental. No change. Power surging/hesitation still intermittent and code P025B pops up (New LPFP Pump #4)
11/8/23 - I replaced the LPFP yet again. No Change. Power surging/hesitation still intermittent and code P025B pops up (New LPFP Pump #5)
Parts installed attempting to resolve this issue.
5 LPFP
LPFP Control Module
HPFP
New ignition coils
AutoTech HPFP Piston
Upstream O2 Sensors
Downstream O2 Sensors
Low Pressure Fuel Pressure Sensor
High Pressure Fuel Pressure Sensor
Direct Injectors
Port Injectors (technically I only have them cleaned and tested)
When the car is running well, it feels great! The below dragy was with full interior + spare tire + ~450 lbs of passengers + 200 lbs of cargo in the trunk + full tank of E85. (driving from norcal to socal)
https://i.imgur.com/VhAhLs4.png
11/25/23 Update:
I spoke had a very productive call with IE and they added the ability to log the LPFP Duty % on the laptop tuning wizard. The issue is very intermittent, but I was able to capture part of it. It might present more in hot weather, I'm not sure.
Log 1 - Low Fuel Pressure: https://datazap.me/u/activemonkey/4th-gear-pull-low-lpfp-av?log=0&data=5-11-12&solo=5
https://i.imgur.com/DcdOGop.jpg
Based on this log and how inconsistent the issue seems to be, I cannot think of another part that would present so erratically. I bought and installed a new LPFP Control Module. While removing the old module I removed the fabric tape and thoroughly inspected the wiring harness but found nothing unusual. I then then retaped it and installed the new module.
Log 2 - New LPFP Control Module: https://datazap.me/u/activemonkey/4th-gear-pull-lpfp-duty-new-lpfp-control-module-normal?log=0&data=9-10-18&solo=18
https://i.imgur.com/3mNqmaO.jpg
After beating on the car for ~45 minutes i could not get the issue to manifest.
11/26/23 Update:
Issue is still there and still intermittent. I just ordered new low pressure injectors as it's the only part of the fueling system i have yet to replace. I'll install them tomorrow and see how it goes.
Short 4th Gear Log: https://datazap.me/u/activemonkey/short-4th-gear-pull?log=0&data=16-19-20&solo=16
https://i.imgur.com/FdN68kL.png
1/2/24 Update:
After replacing low pressure injectors the issue is still there. I even replaced the supercharger clutch incase that was slipping, but no luck. I basically gave up on E85 (more or less) and flashed the IE 93 octane tune but the issue was even present on the IE 93 octane file!! Admittedly not as severe. After replacing the entire fuel system and doing the back and forth with IE tech support to no avail, I switched to Jackal and poof, no more issues. I'm currently running Jackal Stage 2+ (187/57) on 93 with zero issues. I'm not saying it was the tune, but it's one hell of a coincidence...
In talking with people smarter than me, the leading theory is that the car was requesting too high of a LPFP duty cycle and it triggers some kind of fuel pump limp mode. If you pull over and turn off and on the car resets and you're good to go again until the issue comes back. I'm building a dual brushless LPFP setup and we'll see if that can flow enough for E85. fingers crossed.
I've been having intermittent power surging/hesitation under WOT while running IE Single Pulley E85 tune for ~10 months and would like to get your thoughts. I feel its worth noting, the power surging/hesitation issue is nonexistent on the 91 octane file. The 91 file runs great, the car is just slower than when I run the E85 file.
My understanding of the way the car handles fuel pressure is the following: The ECU requests a specific pressure low pressure fuel pressure. The ECU then ramps up the duty cycle of the LPFP making it pump more fuel and build pressure. The cars first layer of control is the fuel pressure regulator on the in tank fuel pump assembly which begins to open up at 5.5 bar and dumps excess fuel bank into the tank. If fuel pressure still gets too high according to the low pressure fuel pressure sensor located under the supercharger on the low pressure fuel rail, the ECU will reduce the LPFP duty cycle to bring down the low pressure fuel pressure. Aside from the below listed parts (which have all been replaced trying to trouble shoot the issue), what could cause a drop in the low pressure fuel pressure or intermittent power surging/hesitation under WOT?
LPFP
LPFP control module
Low pressure fuel pressure sensor
High pressure fuel pressure sensor
HPFP
Logs showing no issue
Log 1: https://datazap.me/u/activemonkey/e70-4th-gear-log?log=0&data=1-21
Log 2: https://datazap.me/u/activemonkey/e70-4th-gear-log-2?log=0&data=13-19
Logs showing issue
Log 3: https://datazap.me/u/activemonkey/e70-power-surging?log=0&data=10-16
Log 4: https://datazap.me/u/activemonkey/e70-power-surging-accidently-hit-kick-down?log=0&data=4-21
*Accidentally hit the kick down on log 4.
After a few file revision from IE, the power surging/hesitation is still intermittent and the only code that pops up is the P025b Fuel Pump Module 'A' Control Circuit Range/Performance.
BACKSTORY
TLDR; Replaced nearly all fuel components and the problem still persists.
LONG VERSION:
Below is a not so brief overview/history.
January 23 I am getting power surging and p310b, p0089 and p025b so I data log, see low pressure from the LPFP and replace LPFP with new pump assembly from Audi. Surging goes away for the most part, but codes are persistent. (New LPFP Pump #1)
April-May 23 Power surging returns. I submit logs to IE, they says the LPFP is bad and needs to be replaced. I replace with another new LPFP from audi. Surging goes away for the most part, but codes are persistent. (New LPFP Pump #2)
June 23 I replace HPFP with new from audi to see if this fixes the surging/hesitation issue or the p310b, p0089 and p025b codes. It does not.
June Sep 23 In an attempt to resolve the codes and power surging/hesitation issue I replace all coils twice, new upstream and downstream O2 sensors, bypass valve and LPFP control module. No change.
Oct 23 - I install an AutoTech HPFP Piston so see if that has any impact. Oh boy did it! Instead of just power surging the car would misfire, EPC light and hide a cylinder. It really seems like the LPFP just cannot keep up. I replace the upgraded HPFP with stock HPFP from Audi and Im back to power surging and p310b, p0089 and p025b. When it does run correctly it does run very will. IE makes revision to E85 File (V1.05) with new fuel set points. Codes p310b, p0089 go away but p025b remains along with intermittent surging/hesitation issue.
10/23/23 Seeing logs with low LPFP AV I buy another LPFP from audi and install it. No change. LPFP values intermittently in the ~3 bar range causing surging/hesitation. To rule out other hardware, I remove, test and clean the port injectors, replace the direct injectors, and the high pressure and low pressure fuel pressure sensors located under the supercharger. While everything is out, I blow out the fuel lines to confirm no debris or obstructions in the lines. No change, LPFP values intermittently in the ~3 bar range causing surging/hesitation. Dealer doesnt want to warranty the pump but accepts return. (New LPFP Pump #3)
10/28/23 I install another new LPFP from a different vendor though the pump is still Continental. No change. Power surging/hesitation still intermittent and code P025B pops up (New LPFP Pump #4)
11/8/23 - I replaced the LPFP yet again. No Change. Power surging/hesitation still intermittent and code P025B pops up (New LPFP Pump #5)
Parts installed attempting to resolve this issue.
5 LPFP
LPFP Control Module
HPFP
New ignition coils
AutoTech HPFP Piston
Upstream O2 Sensors
Downstream O2 Sensors
Low Pressure Fuel Pressure Sensor
High Pressure Fuel Pressure Sensor
Direct Injectors
Port Injectors (technically I only have them cleaned and tested)
When the car is running well, it feels great! The below dragy was with full interior + spare tire + ~450 lbs of passengers + 200 lbs of cargo in the trunk + full tank of E85. (driving from norcal to socal)
https://i.imgur.com/VhAhLs4.png
11/25/23 Update:
I spoke had a very productive call with IE and they added the ability to log the LPFP Duty % on the laptop tuning wizard. The issue is very intermittent, but I was able to capture part of it. It might present more in hot weather, I'm not sure.
Log 1 - Low Fuel Pressure: https://datazap.me/u/activemonkey/4th-gear-pull-low-lpfp-av?log=0&data=5-11-12&solo=5
https://i.imgur.com/DcdOGop.jpg
Based on this log and how inconsistent the issue seems to be, I cannot think of another part that would present so erratically. I bought and installed a new LPFP Control Module. While removing the old module I removed the fabric tape and thoroughly inspected the wiring harness but found nothing unusual. I then then retaped it and installed the new module.
Log 2 - New LPFP Control Module: https://datazap.me/u/activemonkey/4th-gear-pull-lpfp-duty-new-lpfp-control-module-normal?log=0&data=9-10-18&solo=18
https://i.imgur.com/3mNqmaO.jpg
After beating on the car for ~45 minutes i could not get the issue to manifest.
11/26/23 Update:
Issue is still there and still intermittent. I just ordered new low pressure injectors as it's the only part of the fueling system i have yet to replace. I'll install them tomorrow and see how it goes.
Short 4th Gear Log: https://datazap.me/u/activemonkey/short-4th-gear-pull?log=0&data=16-19-20&solo=16
https://i.imgur.com/FdN68kL.png
1/2/24 Update:
After replacing low pressure injectors the issue is still there. I even replaced the supercharger clutch incase that was slipping, but no luck. I basically gave up on E85 (more or less) and flashed the IE 93 octane tune but the issue was even present on the IE 93 octane file!! Admittedly not as severe. After replacing the entire fuel system and doing the back and forth with IE tech support to no avail, I switched to Jackal and poof, no more issues. I'm currently running Jackal Stage 2+ (187/57) on 93 with zero issues. I'm not saying it was the tune, but it's one hell of a coincidence...
In talking with people smarter than me, the leading theory is that the car was requesting too high of a LPFP duty cycle and it triggers some kind of fuel pump limp mode. If you pull over and turn off and on the car resets and you're good to go again until the issue comes back. I'm building a dual brushless LPFP setup and we'll see if that can flow enough for E85. fingers crossed.