Flex Fuel Conversion

JONBLARC7 · June 5, 2020

Confirmed at lunch that the line was causing a restriction. I removed it and just plug the fuel lines back into there stock spot and my fuel trims went back to the way it was before.

I'm going to go with the DXS fitting that is straight instead. I never had a restriction with the Russell fitting that where straight. So I'm going to go back to something like that.

SinisterZ71 · June 5, 2020

8 hours ago, JONBLARC7 said:

Have you logged you fuel trims after adding this fuel line. After my Russell fittings failed I decided to use this line. But I didn't from memory remember you flipped the fitting coming from the tank. So my sensor it hanging out over the drive shaft. But it shouldn't flow much different than how you have it set up.

I've been dialing in my spark since I already had my MAF and VE fueling dialed in pretty good.

After the only thing I did to the truck last night was I added that fuel line. Now under WOT my fuel trims read much leaner. At idol and cruising it's fine but I think it's causing a bottle neck at WOT. My MAF error went from -1 to -2 to 8 to 10 and the wideband confirms it. I'm usually around .86 lambda and before I noticed it was lean I was at .95. Not good for WOT

I'm going to go out and take it off a log again and see if it goes back to the way it was be for.

No, I haven't logged my fuel trims. But this fuel line is the factory part for flex fuel trucks - if it is causing a bottleneck to fuel flow at WOT, wouldn't it do so on all factory flex fuel trucks equipped with this same fuel line???

JONBLARC7 · June 6, 2020

You could be 100% right. Because like I said the way I bent the line wasn’t quite like yours. I didn’t realize you spun the line from the tank around 180 degrees.

just wanted to let you know. Mine was being pinched or blocked somewhere.

SinisterZ71 · June 8, 2020

On 6/5/2020 at 9:45 PM, JONBLARC7 said:

You could be 100% right. Because like I said the way I bent the line wasn’t quite like yours. I didn’t realize you spun the line from the tank around 180 degrees.

just wanted to let you know. Mine was being pinched or blocked somewhere.

I might have some time to do some datalogging on my truck later today, if I do, I'll get back to you with my findings.

Please let us know what you come up with on your suspected fuel line kink issue.

JONBLARC7 · June 8, 2020

Here is how I had the line bent. If it’s not the new fuel line I guess I could of been punching the flexible fuel line coming off the fuel tank. But don’t believe that’s it. If you logs come back fine. I’ll dig into it deeper.

SinisterZ71 · June 9, 2020

I recorded a log yesterday. Flex fuel sensor was reporting 72.5% ethanol in fuel content, ambient (outside) air temp was 91 deg F. WOT narrow band o2 voltage was 868mv on B1S1 and 880mv on B2S1 (plenty rich). STFT on both banks was 0% at WOT and LTFT on B1 was -7.8% while LTFT on B2 was -9.4%. So it wasn't running lean at WOT in my case. If anything, the tune could stand to have a little fuel pulled out to correct for the negative fuel trim numbers.

Edited June 9, 2020 by SinisterZ71

JONBLARC7 · June 9, 2020

Thanks

I was thinking about it last night and maybe one of the clips on the top of the fuel tank that hold the soft line in place was pinching that line. I'll hook it up again and spin the soft fuel line around like you have it and log again.

M H · June 23, 2020

edit***This line makes the sensor have to be directly above the driveshaft. I used plastic to to make a mount/shelf, I'll change the line orientation later, don't recommend this though***edit

https://www.rockauto.com/en/moreinfo.php?pk=10359092&jsn=14898

Hey CC guys, I found this. Same line but straight, and few cents cheaper.

AC Delco part #20967834

Edited July 8, 2020 by M H

JONBLARC7 · July 31, 2020

I tired the line post earlier again but I spun around the top fitting so the tank line came in from the drivers side door.

Something must be pinched or it shrunk when I heated it up to straighten it out. With the line added it makes my WOT go lean. Around .91 to .93 lambda, Then I can come right back home take the line off and go for a log again and it goes right back to where it should be around .87 lambda.

This is all checked with my wideband. So be careful.

The Russell fitting didn't have this problem but they failed on my after two years. So I'm going to go back to that style and just use the more expensive DSX fitting.

You can't go by your STFT or LTFT because it doesn't reference those during WOT pulls. That's why the STFT go to 0% as soon as the truck goes into PE.

SinisterZ71 · July 31, 2020

6 minutes ago, JONBLARC7 said:

You can't go by your STFT or LTFT because it doesn't reference those during WOT pulls. That's why the STFT go to 0% as soon as the truck goes into PE.

True, but I wasn't looking at my fuel trims at WOT. I was watching my narrow band B1S1 and B2S1 o2 sensor readings - and both were above 900mv during the WOT pulls (which would generally indicate richer than 12:1 AFR).

JONBLARC7 · July 31, 2020

Good deal I just want people to know and double check by logging before you go ripping around. Obviously something when wrong with my line when I heated it up and bent it out straight.

.93 lambda might hurt something

SinisterZ71 · July 31, 2020

1 hour ago, JONBLARC7 said:

Good deal I just want people to know and double check by logging before you go ripping around. Obviously something when wrong with my line when I heated it up and bent it out straight.

.93 lambda might hurt something

.93 lambda equates to about 13.7:1 AFR which is still a bit lean for an N/A engine at WOT for my liking (I would prefer no leaner than 13.0:1 AFR), but not as terrible as 1.00 lambda (14.7:1) would be.

Edited July 31, 2020 by SinisterZ71

JONBLARC7 · July 31, 2020

Yea I'm tuning it my self so I'm targeting 1.135 in PE which is .88 Lambda. I usually hang right around .87 to .88 in a pull. I still need to clean up my VE table alittle.

Edited July 31, 2020 by JONBLARC7

lucas287 · August 4, 2020

On 6/23/2020 at 12:06 PM, M H said:

Hey CC guys, I found this. Same line but straight, and few cents cheaper.

AC Delco part #20967834

Hey @M H did you end up using this part #? Looks like a good solution rather than boiling/bending the previously mentioned connector!

M H · August 6, 2020

I would not recommend. I will probably switch to hard line adapters or something different. I made a splash guard out of an old wheel liner, mounted the sensor to it, but its directly above the drive shaft (not optimal).