Flex Fuel sensor readings drop when in boost - Page 2 - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

RyangAsh · 05-07-2020, 03:56 PM

Quote:

Originally Posted by dreksnot

I had it in the supply on my LS3 setup with LPE twin-fuel pump supplying. No issues. When the Triple Fore was installed we used the original supply fuel line as the new return line, keeping the FF sensor in place. Can't really think why that would be a problem.

I think it's possible to give a falsified ethanol percentage reading when flow isn't 100 percent across the sensor. This is purely speculation.

stevieturbo · 05-07-2020, 04:29 PM

I would definitely be investigating those huge fuel pressure drops.

Easiest first check, is with a full tank so any fuel surge etc can be ruled out.

Greenhornet2 · 05-07-2020, 06:37 PM

Quote:

Originally Posted by dreksnot

I start digging and looking and find other weird stuff. This time my E% dropped from my expected 65% to 58%, then 55%, then 50%, returning to the expected 65% after letting off crossing the end of the quarter.

Now, the weird stuff - my FP is dropping when launching. I'm doing my 2-step thing (mine only cuts ignition), building a little boost, easing out the clutch and see my FP tank to 30 (see 1st pic). It recovers. This happened 2 of out 11 runs. The other time was when I activated my anti-lag (timing retard) and while it built up boost, the FP dropped out (see 2nd pic). So, this looks boost/fuel pump related? That 2nd picture, however, did not have the E% drop the whole run.

How much fuel in the tank? Do the pumps have buckets?

eLeSthree · 05-07-2020, 06:44 PM

I had these issues when I had fuel pressure drop. Pulled the triples and found torn/mis-aligned o rings.

Im betting you’re return line is not full due to low fp and getting some air across the sensor.

Problem with ff sensor in feed is the bottle neck. But the bypass cures that.

dreksnot · 05-07-2020, 08:38 PM

Quote:

Originally Posted by Greenhornet2

How much fuel in the tank? Do the pumps have buckets?

1/2 to 3/4 tank full

dreksnot · 05-07-2020, 08:38 PM

Quote:

Originally Posted by eLeSthree

I had these issues when I had fuel pressure drop. Pulled the triples and found torn/mis-aligned o rings.

Im betting you’re return line is not full due to low fp and getting some air across the sensor.

Problem with ff sensor in feed is the bottle neck. But the bypass cures that.

One thing I do have it the FF sensor is up high

RyangAsh · 05-08-2020, 10:47 AM

Quote:

Originally Posted by eLeSthree

I had these issues when I had fuel pressure drop. Pulled the triples and found torn/mis-aligned o rings.

Im betting you’re return line is not full due to low fp and getting some air across the sensor.

Problem with ff sensor in feed is the bottle neck. But the bypass cures that.

This was what I was trying to say in short. Not sure the root of the problem but there is air going across the sensor.

Greenhornet2 · 05-08-2020, 11:28 AM

I agree with the above, sounds like you are sucking air from somewhere

Big Biscuits · 05-19-2020, 01:57 PM

Where are you getting power and ground from that supply the FF sensor?

dreksnot · 05-19-2020, 02:00 PM

Quote:

Originally Posted by Big Biscuits

Where are you getting power and ground from that supply the FF sensor?

If I remember correctly, I believe I made a harness and put it in either the injectors/ignition coil path.

Big Biscuits · 05-19-2020, 02:01 PM

I agree with flow across the sensor being an issue, but a sensor that close to the regulator? Could happen I guess. I keep a close eye on mine being so far back near the tank, but so far, so good.

Big Biscuits · 05-19-2020, 02:04 PM

Quote:

Originally Posted by dreksnot

If I remember correctly, I believe I made a harness and put it in either the injectors/ignition coil path.

I wonder if you are getting voltage drop from the shared source? I ran mine to an ignition power and used chassis ground to keep circuits separate. Just a thought. Would be an easy check.

stevieturbo · 05-19-2020, 04:43 PM

Quote:

Originally Posted by Big Biscuits

I wonder if you are getting voltage drop from the shared source? I ran mine to an ignition power and used chassis ground to keep circuits separate. Just a thought. Would be an easy check.

Unless it was a massive drop, voltage should not affect the output

I guess one cheap/easy thing to try would be to try and gently squeeze up any return line after the sensor bit by bit so there is a bit of resistance to flow after the sensor, but not so much it may affect pressure.

Big Biscuits · 05-19-2020, 06:46 PM

He is running hard line I do believe.

05-07-2020, 06:44 PM	#18
eLeSthree Drives: 2011 Camaro SS 6sp Join Date: Nov 2016 Location: Drivers Seat Posts: 1,904	I had these issues when I had fuel pressure drop. Pulled the triples and found torn/mis-aligned o rings. Im betting you’re return line is not full due to low fp and getting some air across the sensor. Problem with ff sensor in feed is the bottle neck. But the bypass cures that. __________________ 2011 Camaro SS---SOLD TMS Dart 427 FED M311s, ESS Tuning G4 Blower, DSX Triple FP Assembly, DSX FF, FIC1300, Mcleod RXT 1200HD, Edlebrock Pro Flo XT 1158whp 1017wtq. 2010 CTS-V A6 - "Stock" SOLD 630whp 658wtq 2024 F-150 RCSB 5.0 4x4 waiting for tunes...

05-08-2020, 11:28 AM	#22
Greenhornet2 Drives: 2011 Camaro 2SS LS3 Whipple Join Date: May 2019 Location: Connecticut Posts: 1,925	I agree with the above, sounds like you are sucking air from somewhere __________________ Whipple 2.9 CAI ID1050x injectors ZL1 Pump JRE FPCM JMS Voltage booster JRE Rough Idle blower cam BTR .660 springs CHE trunnion kit 1 7/8 Speed Engineering Borla Atak JRE scoop 1.5" lowering springs BMR trailing arms and toe links Cradle inserts 704WHP 603WTQ 93 octane

05-19-2020, 01:57 PM	#23
Big Biscuits Drives: 2010 1SS LS3 Join Date: Aug 2019 Location: Waxahachie, TX Posts: 276	Where are you getting power and ground from that supply the FF sensor? __________________ 2010 CGM 1SS 408/4L80E/ZL1 ESS G4

05-19-2020, 02:01 PM	#25
Big Biscuits Drives: 2010 1SS LS3 Join Date: Aug 2019 Location: Waxahachie, TX Posts: 276	I agree with flow across the sensor being an issue, but a sensor that close to the regulator? Could happen I guess. I keep a close eye on mine being so far back near the tank, but so far, so good. __________________ 2010 CGM 1SS 408/4L80E/ZL1 ESS G4

05-19-2020, 06:46 PM	#28
Big Biscuits Drives: 2010 1SS LS3 Join Date: Aug 2019 Location: Waxahachie, TX Posts: 276	He is running hard line I do believe. __________________ 2010 CGM 1SS 408/4L80E/ZL1 ESS G4

05-07-2020, 04:29 PM	#16
stevieturbo Drives: it changes Join Date: Nov 2010 Location: Norn Iron Posts: 1,126	I would definitely be investigating those huge fuel pressure drops. Easiest first check, is with a full tank so any fuel surge etc can be ruled out.