Stock 2016 Z06 fuel issue. Stock tune/lemon?

[Mikejr89]

Car is a 2016 Z06 I bought second hand with 5k miles. Car is bone stock. For last several months ever since I got it, it would hesitate and would accelerate slower at WOT at higher rpm in 3rd and 4th gear, usually around 120mph.

One time it went into limp mode and cel p228c.

Had it data logged and it was indeed losing pressure on the high side at 5000 plus rpm. Throttle body even started to close a bit too.

Since then, the fuel pressure regulator sensor and high pressure fuel pump were replaced and it did not solve the issue.

Further data logging showed the low side pump also losing pressure at during that same timeframe.

Car runs perfectly normal aside from 3rd and 4th gear in the upper rpm range at wot.

I found other posts on here where other members talking about a similar issue which some believed to be related to Cat Over Temp on the stock tune. Has anyone else had any experience with this? I find it hard to believe the low side fuel pump could be the problem. My tuner is scratching his head too.

Here’s a link to one of the previous threads.
https://forum.hptuners.com/showthrea...525#post556525

[Joshinator99]

Car is a 2016 Z06 I bought second hand with 5k miles. Car is bone stock. For last several months ever since I got it, it would hesitate and would accelerate slower at WOT at higher rpm in 3rd and 4th gear, usually around 120mph.

One time it went into limp mode and cel p228c.

Had it data logged and it was indeed losing pressure on the high side at 5000 plus rpm. Throttle body even started to close a bit too.

Since then, the fuel pressure regulator sensor and high pressure fuel pump were replaced and it did not solve the issue.

Further data logging showed the low side pump also losing pressure at during that same timeframe.

Car runs perfectly normal aside from 3rd and 4th gear in the upper rpm range at wot.

I found other posts on here where other members talking about a similar issue which some believed to be related to Cat Over Temp on the stock tune. Has anyone else had any experience with this? I find it hard to believe the low side fuel pump could be the problem. My tuner is scratching his head too.

Here’s a link to one of the previous threads.
https://forum.hptuners.com/showthrea...525#post556525

Not sure why your tuner is stumped…?!? If you have a bad low side pump you will not have enough pressure to feed the high side pump. That will in turn drop its output pressure leading to excessive injector pulse width and running lean under heavy load. If the low side pressure is not keeping up on a stock car, I would start there.

[pisces_0]

The low-side pump is definitely suspect. Dropping pressure at high load and high RPM will only continue to get worse as the pump degrades.

Joshinator99 is spot-on. The HPFP can't feed the injectors if the low side pressure isn't there.

I hit this wall after installing a flex fuel sensor and converting to E85. First hard pull on E85, the low side pressure tanked, high side pressure dropped, IPW shot up and the engine went dead-lean. A Walbro 465 went in shortly after and low side pressure holds steady at 72 PSI.

[TriPinTaZ]

Your high side shouldn't be tanking like that even if the low side is in the 50-60psi range. Assuming the car is bone stock. Stock intake. No mods. Even if the low side reaches 50psi, the high side should be able to maintain 2000psi or higher if bone stock. Have you inspected or replaced the fuel filter? I don't think that is the issue but it wouldn't hurt to look.

Have you checked or replaced the fuel hose under the blower that feeds the high side pump? There is a check valve in that hose that has been known to fail and cause high side pressure issues on the 2015-2016 models. GM Corrected this for 2017+.

[albertoasuncionroig@gmail]

It happens exactly the same. I'm in Spain and nobody knows anything. I'm a bit desperate. Does anyone know what the solution is? YEAR 2015

[TriPinTaZ]

It happens exactly the same. I'm in Spain and nobody knows anything. I'm a bit desperate. Does anyone know what the solution is? YEAR 2015

Check/replace the fuel line with the check valve as I said above.

[albertoasuncionroig@gmail]

Check/replace the fuel line with the check valve as I said above.

. OK thank you. I will try. I will tell news

[Mikejr89]

Car has been “fixed”.

I say fixed because the solution was turning off Cat Over Temp protection it stopped sucking the pumps dry. Low pressure side never dropped below 70 psi. Put in AFE cat deletes to go with it. From what I’ve read and from my own experience several people have had this issue.

[TriPinTaZ]

what was the high side pressure at after the "fix"?

[albertoasuncionroig@gmail]

thank you man