Ethanol / Flex Fuel Sensor
Former Vendor
Joined: Feb 2010
Posts: 33
From: Houston, TX
Rep Power: 0
how much power is your car making that you are trying to use 4 fuel pumps and a stock FPR??
few things I see is that FP is not rising 1 to 1 and then in 3rd gear when it cuts boost the fuel pressure actually spikes even higher, that's because the regulator cant bypass all the fuel from all your pumps.
I would revisit the return side of your fuel system. either get new rails, or modify stock rails ( 2x driver side rails ), don't use stock regulator and get a nice Weldon one.
few things I see is that FP is not rising 1 to 1 and then in 3rd gear when it cuts boost the fuel pressure actually spikes even higher, that's because the regulator cant bypass all the fuel from all your pumps.
I would revisit the return side of your fuel system. either get new rails, or modify stock rails ( 2x driver side rails ), don't use stock regulator and get a nice Weldon one.
Running that much fuel through a stock FPR is asking a lot out of it. Along with 4 pumps which seems like a lot of work to stage, why not just run 2 Walbro pumps? Are the pumps staged to come on at the appropriate time on ethanol vs pump? This may not matter but just thinking.
Your ethanol content is dropping out in less than a second, which to me seems like wiring. Have you tried grabbing the wiring at the ethanol sensor (within an inch or so) at idle and wiggling it? See if the reading bounces. Then try at any connections you may have along the way and at the ECU.
Final thought, are you sure the reading is not cutting out on pump fuel? Or are you saying it just doesn’t enter limp mode? Going from E10 to E0 isn’t a big deal and the ECU can compensate. Going from E30 (or higher) to E0 is asking too much.
Registered User
Joined: Dec 2007
Posts: 635
From: Houston
Rep Power: 111
Sound like you need a bigger fuel system Aftermarket line, rails, and regulator. I would swap out the 4 pumps to a large single pump or dual brushless. I am running the SRM dual brushless and have plenty of fuel on e85 at 1300whp. 4 pumps is leaving you open for failure, Fuel system is nothing you want to skimp on.
Hey Guys,
First of all thank you all for such valuable input, It really helped alot.
Just an update, I Have been traveling alot since this thread, so car has been parked since.
I have dropped the car off to a reputable garage who has experience doing custom Porsche work. This is what we are planning to do:
I should hopefully have the car running sometime next week and will try take some pictures and update this thread with the results.
Once the fueling is sorted I am planning on reconnecting the aquamist and work on a pump + meth tune as summer is fast approaching here (50 degrees FML)
First of all thank you all for such valuable input, It really helped alot.
Just an update, I Have been traveling alot since this thread, so car has been parked since.
I have dropped the car off to a reputable garage who has experience doing custom Porsche work. This is what we are planning to do:
- Addtional feed line and stock feed line meet at a T and then each rail gets its own feed line.
- Each rail will have its own return line and meet at an aftermarket FPR then have 1 return line to the tank.
- The flex fuel sensor will be located on the return after the FPR
- Replace all fuel lines
- Custom billet fuel rails (They had a few on hand for the 991, they will test fit and see if it works, visual inspection showed it could work with a custom bracket)
- 6AN fittings
I should hopefully have the car running sometime next week and will try take some pictures and update this thread with the results.
Once the fueling is sorted I am planning on reconnecting the aquamist and work on a pump + meth tune as summer is fast approaching here (50 degrees FML)
Registered User
Joined: Oct 2015
Posts: 71
From: Delaware
Rep Power: 13
Sounds like a solid plan, however I'm surprised that you'd still maintain the meth injection since you'll have the flexfuel capabilities. Will this be used when only on pump gas and not on Ethanol? Once I switched my Supra to cornjuice I only ever go back to gasoline when in a long trip situation or to pickle the system for winter storage... Best of luck!
Sounds like a solid plan, however I'm surprised that you'd still maintain the meth injection since you'll have the flexfuel capabilities. Will this be used when only on pump gas and not on Ethanol? Once I switched my Supra to cornjuice I only ever go back to gasoline when in a long trip situation or to pickle the system for winter storage... Best of luck!
Unfortunately ethanol isn't available at the gas stations here, so we buy it in 200L drums, it is expensive but definitely still cheaper than race gas.
The temperatures here go crazy high in summer so meth will be used to keep things cool, it's currently 38 degrees celcius lol
Thread
Thread Starter
Forum
Replies
Last Post
Chinaski-NY
997
8
May 8, 2013 05:47 PM