2006 GT on3 turbo going lean under boost

RED09GT

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Yes, right out of the OBD2 port.
Too the best of my knowledge the FRP sensor reference is always after the blower where it will see vacuum or pressure. I don’t see how it could work in front of the blower.

I didn't think that would be the case but was looking for an explanation of why your fuel pressure increases. It is not easy to tell without being able to flip through your PID's but it looks like once your load reaches the max of 2.0, that is when your fuel pressure increases-that makes sense as it is sort of a work around for the processor not knowing the exact amount of air going through it. As long as the A/F is correct, it is not an issue, just a different approach.
 

Midlife Crises

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There must be something tuners do in the file configuration to make fuel pressure look like that. I don’t understand how the spray pattern could be maintained if fuel pressure does not rise and fall with manifold pressure.
 

Juice

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There must be something tuners do in the file configuration to make fuel pressure look like that. I don’t understand how the spray pattern could be maintained if fuel pressure does not rise and fall with manifold pressure.
Increase injector duty cycle OR increas pressure. Both methods will put more fuel in.
In the old days, like on my 91, the pcm had no way to know how much boost is going in the engine. So the boost sensitive regulator increases fuel pressure.
Like it has been said, different approach getting the same results.
 

Midlife Crises

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injector duty cycle
The injector duty cycle refers to the amount of time the injector is activated and will put in more or less fuel over time. Agreed. It has nothing to do with maintaining the correct Delta between the injector pressure and the manifold pressure. Simple; best spray pattern at 39psi and zero manifold pressure. Same spray pattern at 49psi and 10psi manifold pressure. Lame spray pattern at 39psi and 10psi manifold pressure.
Why is the fuel rail pressure sensor biased against the manifold pressure? So the fuel pressure can rise and fall with the manifold pressure automatically.
 

Beak O Boost

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I got back to looking at the car. I inspected the FRP and hoses all look ok. I got to thinking about what I could have done wrong and the only things I could think of were when I installed the engine I plugged my msd 2 step connectors in the wrong connector and I plugged the knock sensors into the plug for the imrc that I am not running anymore. Im thinking maybe I smoked the pcm somehow. So I ordered up a used pcm. I returned vehicle to stock and I plugged it in and programmed an additional key so it would start. Then I tried to program tune back in with my sct handheld and it said wrong vehicle. I started car and ran it. It seems to run pretty good. Then i took it out for a road test. now its reading 11 to 12:1 at wot. I think I shouldnt push my luck because it might have way too much timing. I still have the 5psi spring in it. I will update after putting a tune back into it. Thanks for all the help so far.
 

stkjock

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The strategy code certainly could have changed with the PCM swap
 

Beak O Boost

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So I got together with my tuner today with the new pcm installed. Everything is working normally now. We stopped at 10psi because traction was becoming an issue. Time to set up some time at the dyno and get it dialed in at higher boost ranges. Does anyone know what the limits of a gt500 fuel system with dw300 pumps? 93 octane and e85? I eventually plan to run e85 once I get it all dialed in. Thanks again for all the help.
 

JeremyH

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Around 700rwhp on e85 is where returnless physically starts not being able to keep up pulse get wider causing pressure fluctuation. (That's the volume of fuel close to 900rwhp potential on gasoline.) The dw300m pumps, 8awg wire upgrade, 8an line and filter and pprv delete on the gt500 fuel system can get you to that range. Just the dw pumps without supporting mods dont do too much over the gt500 pumps. They tend to run hot and cavitate.

Do you have an actual boost and power goal?
 

Beak O Boost

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I was hoping for around 700 on e85. I might just install a fuel system over the winter so it will be done right. My end goal is get the car to run as close to 10.0 as I can get.
 

Waakeeen

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Around 700rwhp on e85 is where returnless physically starts not being able to keep up pulse get wider causing pressure fluctuation. (That's the volume of fuel close to 900rwhp potential on gasoline.) The dw300m pumps, 8awg wire upgrade, 8an line and filter and pprv delete on the gt500 fuel system can get you to that range. Just the dw pumps without supporting mods dont do too much over the gt500 pumps. They tend to run hot and cavitate.

Do you have an actual boost and power goal?

I'm on the fence on how to give my car that extra fuel that it needs. I currently have dual gt500 pumps and was aiming for 700hp. I wanted to get this kit https://www.deatschwerks.com/9-305-1035 along with 80lb injectors. All this is in theory, it's up to the tuner to get the max hp safely but in your opinion is it a waste to swap out the pumps?
 

RED09GT

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If you are using E85and aiming for 700rwhp, you will be better off going to a return style system.
If you are sticking with gasoline, do the fuel line and wiring upgrades first, then do the DW pumps.
 

Waakeeen

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If you are using E85and aiming for 700rwhp, you will be better off going to a return style system.
If you are sticking with gasoline, do the fuel line and wiring upgrades first, then do the DW pumps.
Just looking at different options, what are thoughts on the VMP bap?
 

RED09GT

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I've never used a BAP but lots of people have used them with success.
With it being close to the same costs and with the fuel pumps being easy to get at in these cars, it comes down to personal preference as both can get you close to the end point of where you can go with a return-less fuel system. The plug 'n play version of the VMP BAP makes things very simple.
 

Waakeeen

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I've never used a BAP but lots of people have used them with success.
With it being close to the same costs and with the fuel pumps being easy to get at in these cars, it comes down to personal preference as both can get you close to the end point of where you can go with a return-less fuel system. The plug 'n play version of the VMP BAP makes things very simple.
Yeah I've heard the same thing too, might go that route and keep y'all posted on how it goes.
 

JeremyH

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You can always add bigger pumps or voltage booster to increase flow potential. The overlooked things are proper wiring to minimize current draw and heat in the pump.(Hotter the pump runs the less it flows both bigger pumps and voltage booster increase current draw). And next overlooked part of the fuel system is the system that moves the fuel from the pump outlets up to the rails and injectors. (Ie. Plumbing on hat, oem fuel line, filter and connection to rail). We are doubling or tripling flow while still powering the pumps and moving the fuel through equipment designed for a 300hp na car. Less than efficient to say the least. There are large gains to be had here. These gains scale with flow hence why I always reccommend doing them first before just adding bigger pumps or voltage booster. A wire upgrade direct from battery to relay and fpdm feed, removing the pprv on the hat and a 8an line and high flow filter upgrade on the gt500 fuel system extends range and on average lowers duty cycle around 30%. That is pretty substantial and these supporting mods are pretty budget friendly, I make and test these kind of upgrades. Well worth it and always reccommend doing them first or in conjunction with more flow when your trying to support more hp and move more fuel.
 
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JeremyH

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Here are some pics showing some of these restrictions in the OEM system. Inside of the pprv, oem rail connection line size etc.

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Waakeeen

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Here are some pics showing some of these restrictions in the OEM system. Inside of the pprv, oem rail connection line size etc.
Wow I’ve never seen them side by side like that! So let me ask you where can I buy such a kit, I’m about simplicity lol
 

Pentalab

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How big in diam is the oem fuel line from tank, filter..up to eng bay ? Is it 3/8" ? Would increasing it to 1/2" reduce some restriction ?
 

RED09GT

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It is 5/16. Switching to a -8AN (aka 1/2") from the hat to the rail makes a big difference.
 

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