Holley efi fpr regulator question.
On The Tree
Joined: Jun 2014
Posts: 118
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From: Winchester Virginia
Does a stock LS vacuum reference the fuel pressure?
I just don't like FP messing with my tune when there is no need to
Last edited by T.Fiddler; Nov 9, 2015 at 09:09 PM.
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I can't tell you how many blown/turbo cars I've helped tune and the first thing I see is the line on the regulator is missing. I ask about it and they look at me like I'm the crazy one. I had one guy tell me that he uses the BAP instead of a vac/boost reference cause it's better. I walked away from that one.
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On The Tree
Joined: Jun 2014
Posts: 118
Likes: 0
From: Winchester Virginia
My car is 5 bar (71 psi) FP with no reference.
Thanks for the input
Last edited by T.Fiddler; Nov 10, 2015 at 11:02 AM.
In some cases they do. 97-98 Corvettes for instance. Some LS trucks do as well.
Not sure why GM changed in that respect. Perhaps cost?
Not sure about the GM supercharged stuff. But in the case of the Hellcat for instance, Dodge uses a PWM fuel pump.
Ron
Not sure why GM changed in that respect. Perhaps cost?
Not sure about the GM supercharged stuff. But in the case of the Hellcat for instance, Dodge uses a PWM fuel pump.
Ron
I started with my fpr referenced to both vacuum and boost(to the manifold pressure), but ended up only referencing to boost.
with the vacuum connected, the low rpm fueling was all over the place, I assume the lopey cam I run caused fluctuations in fuel flow that made it hard to tune idle and off idle. Once I removed the vacuum reference, and tuned accordingly, all was good.
with the vacuum connected, the low rpm fueling was all over the place, I assume the lopey cam I run caused fluctuations in fuel flow that made it hard to tune idle and off idle. Once I removed the vacuum reference, and tuned accordingly, all was good.
Last edited by 3pedals; Nov 10, 2015 at 10:02 AM.
On The Tree
Joined: Jun 2014
Posts: 118
Likes: 0
From: Winchester Virginia
I started with my fpr referenced to both vacuum and boost(to the manifold pressure), but ended up only referencing to boost.
with the vacuum connected, the low rpm fueling was all over the place, I assume the lopey cam I run caused fluctuations in fuel flow that made it hard to tune idle and off idle. Once I removed the vacuum reference, and tuned accordingly, all was good.
with the vacuum connected, the low rpm fueling was all over the place, I assume the lopey cam I run caused fluctuations in fuel flow that made it hard to tune idle and off idle. Once I removed the vacuum reference, and tuned accordingly, all was good.
WHEW! at least I am not the only one !
I only run a boost line-with vac. also it pulled down the FP from 43 to around 36, kind of ads to the tuning
Nascar used to use the vac to lean out the engines on caution laps to get a clean restart, but I just never saw any advantage otherwise-not sure if they use it on FI now
Nascar used to use the vac to lean out the engines on caution laps to get a clean restart, but I just never saw any advantage otherwise-not sure if they use it on FI now