1998 Z71 Build

[L31MaxExpress]

Don't hate me or step into that flex fuel sensor just yet with the 4x. I had flex working with 24x. When I swapped to 4x with the 383 I had been running straight gasoline. I had the flex fuel sensor on it but it was stuck at the prvious ethanol % once I enabled it so it appeared to be working. I topped off the tank and the sensor never moved the alcohol %. 4x crank sensor bit kicks my flex fuel sensor off. Tayto and I are trying to find a work around for it. The code is all enabled on the surface, something between throwing the switch for 24x and 4x is messing with it. Its a disappointment for me as well at the moment. The good news is I set the stoich up for the E85, gave it a timing bump above 0.48 gm/cyl and it has never run better than on the P59 so not all is lost.

Mine has not been lean on hot starts.if you are running the marine intake I can send you my latest transient fuel stuff. Its not exactly perfect but it is a heck of a lot better than it was.

 

[Awest623]

I believe the 2002 Tahoe flex fuel tune doesn't have a custom OS, so no 2 bar there.

It does with hp tuners, just downloaded to verify

You must be registered for see images attach

You must be registered for see images attach

 

[Supercharged111]

Well ain't that some shjt.

 

[Awest623]

Don't hate me or step into that flex fuel sensor just yet with the 4x. I had flex working with 24x. When I swapped to 4x with the 383 I had been running straight gasoline. I had the flex fuel sensor on it but it was stuck at the prvious ethanol % once I enabled it so it appeared to be working. I topped off the tank and the sensor never moved the alcohol %. 4x crank sensor bit kicks my flex fuel sensor off. Tayto and I are trying to find a work around for it. The code is all enabled on the surface, something between throwing the switch for 24x and 4x is messing with it. Its a disappointment for me as well at the moment. The good news is I set the stoich up for the E85, gave it a timing bump above 0.48 gm/cyl and it has never run better than on the P59 so not all is lost.

Mine has not been lean on hot starts.if you are running the marine intake I can send you my latest transient fuel stuff. Its not exactly perfect but it is a heck of a lot better than it was.

I wasn't aware of that, just ordered all the parts to install it today. No worries, I'll take a look into it too.

The lean hot starts are still happening, but I think I finally figured it out. My fuel lines run pretty close to my long tube headers, it might be heating up the fuel enough to cause the lean conditions. Makes sense because it would also go 5-10% lean just sitting in traffic.

I took some good logs today of the hot start, for now I'm gonna play with the enrichment tables using the info from my log. In the future, I'll try rerouting the fuel line away from the headers.

 

[Awest623]

Don't hate me or step into that flex fuel sensor just yet with the 4x. I had flex working with 24x. When I swapped to 4x with the 383 I had been running straight gasoline. I had the flex fuel sensor on it but it was stuck at the prvious ethanol % once I enabled it so it appeared to be working. I topped off the tank and the sensor never moved the alcohol %. 4x crank sensor bit kicks my flex fuel sensor off. Tayto and I are trying to find a work around for it. The code is all enabled on the surface, something between throwing the switch for 24x and 4x is messing with it. Its a disappointment for me as well at the moment. The good news is I set the stoich up for the E85, gave it a timing bump above 0.48 gm/cyl and it has never run better than on the P59 so not all is lost.

Mine has not been lean on hot starts.if you are running the marine intake I can send you my latest transient fuel stuff. Its not exactly perfect but it is a heck of a lot better than it was.

And I'm still running the factory intake with bigger injectors, but I'd appreciate the transients just to look at. They wouldn't line up for me anyways with my aluminum heads but I've never been good with tuning transients.

 

[Supercharged111]

Mine had issues with p!s$ warm restarts back in MI, but not nearly as bad here in CO.

 

[L31MaxExpress]

And I'm still running the factory intake with bigger injectors, but I'd appreciate the transients just to look at. They wouldn't line up for me anyways with my aluminum heads but I've never been good with tuning transients.

I have aluminum heads with ~210cc runners.

 

[Awest623]

I have aluminum heads with ~210cc runners.

Gotcha. I have 190cc runners on mine. Would be interested to look at your transients

 

[Awest623]

I should probably try adding some heat shielding to the fuel lines in addition to relocating them. The flex fuel stuff is coming Wednesday. I have to convert the pressure line to AN to fit the sensor anyways so the line relocation will be easy, I'll pick up some thin sheet metal to form into shielding.

 

[Awest623]

Mine had issues with p!s$ warm restarts back in MI, but not nearly as bad here in CO.

My newest thought is I'm overheating my fuel through the factory metal fuel lines, they run pretty close to my long tube headers. Since I have to run AN tubing anyways for the flex fuel sensor, I'm going to route it as far away from the exhaust as possible, with some heat shielding to boot. See if that fixes the problem