Fuel delivery issues, 2018 Z06

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Jan 3, 2024 | 12:44 AM

Nite RNR

Thread Starter

Heel & Toe

Joined: May 2022

Posts: 21

Likes: 2

Fuel delivery issues, 2018 Z06

Hello- I have an 18 I recently picked up. I went ahead and set it up for E85, basically right away. I was under the advisement of my tuner, who had said that the fuel system should have no issues keeping up.

The car is currently stock, but does have Flex fuel and tune, as well as a car less x pipe.

when getting into the higher rpm’s the fuel pressure dropped to around 1100psi in the rail, and it started missing. This was happening even on E45 mix. I have have plans to start making more power- but need to get this sorted out before I get to work! I am assuming it’s the low side pump, but is there a higher performing setup? Or should I go DSX auxiliary? What has worked for you guys?

I plan to at minimum run a CAI, upper pulley, and maybe port the blower for starters. I would like to be able to support those mods, but the fuel system is going to be my limiting factor.

thanks in advance!

Jan 5, 2024 | 05:31 PM

C7&7

Le Mans Master

Joined: Mar 2010

Posts: 7,050

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From: DFW TX

A stock z06 should be able to handle flex fuel, your tune isn't right. The moment you pulley it you'll have issues though.

Jan 5, 2024 | 06:16 PM

Nite RNR

Thread Starter

Heel & Toe

Joined: May 2022

Posts: 21

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Quote:

Originally Posted by C7&7

A stock z06 should be able to handle flex fuel, your tune isn't right. The moment you pulley it you'll have issues though.

Right? That’s why I’m sort of confused. Everything I read is that I should be just fine. I discovered the issue on a run at the drag strip and when she got up into the high Rpm and mph, just started missing. Still ran an 11.0 on Michelin pilots though.

I knew I would have issues with a pulley involved, but am not happy about it happening from the jump on a basically stock car. I guess I would like to get it squared away of figured out before I dump money into parts. So I pulled a log from the track, and when it started missing the rail pressure had dropped to 1800 with a demand of 2900psi. Here is a snapshot of that occurring, but it last until throttle was pulled.

Last edited by Nite RNR; Jan 5, 2024 at 07:42 PM.

Jan 5, 2024 | 07:26 PM

Eli-Z06

Pro

Joined: Apr 2018

Posts: 731

Likes: 90

From: Eastern Pa

Fuel system

I have the DSX low side pump, those guys are Great to deal with...! Customer support is Excellent...! The fuel side of the Tune is a little tricky to set up, and there are some nuisance-codes that Must be turned off to avoid the check engine light to come on. They were nice enough to send my tuner the Correct fuel log to download into my tune..! My car put 825 HP and 880 TQ to the tire on the flex fuel setup, custom cam with the extra fuel lobe, ported stock blower, 103 throttle body, and an upper pulley.

Jan 5, 2024 | 07:48 PM

Nite RNR

Thread Starter

Heel & Toe

Joined: May 2022

Posts: 21

Likes: 2

Quote:

Originally Posted by Eli-Z06

ELI-

hey! Those are stout numbers! That sounds like exactly the setup I’m looking for, parts wise. Though I hadn’t intended on swapping cams. For your setup, with the aux pump, are you getting ample fuel? I was hoping to run the DSX kit, then port the blower and run a pulley also. Would that cam you’re running be required? Also- are you able to run pump E85, or do you dilute it? Thank you for your help!

also, who did you use for the porting??

Jan 5, 2024 | 09:51 PM

Eli-Z06

Pro

Joined: Apr 2018

Posts: 731

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From: Eastern Pa

The stock blower and 103 throttle body is ported by Kong out here in PA. Not sure if the cam lobe is necessary, that probably be a good question for DSX. But if you're putting a cam in the motor, you might as well get the fuel lobe, I would definitely upgrade the stock lifters to the set of Johnson's with the t-bar...! I had four stock lifters going bad with less than 30,000 mi on the car...! I also upgraded the exhaust valves to a good strong incandel valves, the stock has a hollow stem valves which is garbage. While I had the heads off I had them ported, I also got rid of the heavy weight of the VVT on the end of the camshaft, LME sells a nice setup and timing cover for that. I run E85 straight out of the pump, I installed all the parts and had to remeasure for push rod length... I really enjoyed rebuilding it myself here are my place, but I really enjoy the power that this thing makes.. the stock clutch holds the power just fine... 👍🏻🇺🇸🏁🏁🏁

Jan 9, 2024 | 02:43 PM

Nite RNR

Thread Starter

Heel & Toe

Joined: May 2022

Posts: 21

Likes: 2

Quote:

Originally Posted by C7&7

A stock z06 should be able to handle flex fuel, your tune isn't right. The moment you pulley it you'll have issues though.

I'm glad you mentioned this- thank you. My tuner was telling me it was a bad HPFP. So I reviewed the logs myself and found the injector pulse width to be 7.3-7.5ms when this drop in pressure was occurring. I compared that to my original logs prior to the tuning adjustments (when there was plenty of fuel pressure), and the pulse widths were around 6ms. I’m thinking the rail was being trained with the time length the injectors were open.

Jan 10, 2024 | 08:23 AM

Internets_Ninja

Safety Car

Joined: Mar 2004

Posts: 4,048

Likes: 1,476

From: South Florida

You should be able to get a little more out of it than that, especially stock. You want the low side to maintain 70-80PSI to get the best performance out of the high side. But in your log screenshot, the low side didn't tank, the high side did. I suspect the car is tuned way too rich for E and you're just wasting fuel.

Do you have a wideband in the car?