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Old 05-25-2014, 11:07 PM   #1
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should i change fuel pressure regulator

So i have bored out the throttle body, did an evoms air intake, enlarged the intake pipe, and installed an ipd plenum
Engine is definatly breathing more air, i can actually hear it sucking in air.
Now i have found some sites suggesting that to take full advantage of the extra air that is being sucked in, its best to change the fuel pressure regulator to one with 4 bar. as far as i know, the standard is 3.8 bar.
My mechanic told me that he doesnt think it will make much difference since the ecu is already telling the injectors how much fuel they need to inject, according to the amount of air that is being sucked in.
any ideas please?
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Old 05-25-2014, 11:21 PM   #2
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Someone else should check me, but off the top of my head, increasing to a 4 bar regulator will probably only make an appreciable impact if the extra air is pushing your current setup to its max and leaning out your air/fuel mixture.

Also, a stronger fuel pressure regulator may overpower the fuel pumps ability to send gas through... Not sure if this is a valid concern when increasing only .2 bars
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Old 05-26-2014, 12:02 AM   #3
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You're mechanic might be spot on with that one. With modifications like that I would definitely look into a tune for the new amount of air coming into the engine. I'm not 100% positive but still pretty sure you should be able to compensate that air with the stock regulator and injectors though.
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Old 05-26-2014, 06:48 AM   #4
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^^^ As all_mota said;

I would suggest that your next step might be a custom ECU tune to balance the additional air with additional fuel. Yes, the stock ECU is trying to do this but there are limits to how far it can go with the stock maps. Through this process the tuner can easily determine if your engine would benefit from a higher pressure fuel regulator.
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Old 05-26-2014, 09:42 AM   #5
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Regardless of what mods you have done to your car there is a excellant chance your fuel injecters are not spraying like they should. 1st step is to have them removed & pressure cleaned & tested. My original fuel system feeds my 3.6L with Cayman air intake fine.
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Old 05-26-2014, 10:01 AM   #6
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to be completely honest, when your car is at WOT, you will have little indication of whether you are fueling adequately or not. At WOT you are open loop and the ecu no longer runs at stoichiometric so the 02 sensors are no longer providing feedback. you could be running lean (fuel system not keeping up) and not know it. especially since this is when the highest demand is placed on the fueling system. aftermarket tune will only help with this if it is in-person (ie, not an out of the box solution like softronic or pedro). perhaps track your timing at WOT to see if the ecu is pulling any time due to excessive detonation from hot running. otherwise, the only way you are going to know is with a wideband o2 sensor.
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Old 05-26-2014, 11:54 PM   #7
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thanks for the info guys.
I think ill start by cleaning my fuel injectors.
I forgot to mention that I had remapped the ecu with the air intake mods already in place.
is there something recommended I can use to put in the fuel tank to clean the injectors, or it wont be a match for actually taking the injectors out and cleaning them?
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Old 05-27-2014, 09:30 PM   #8
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More air can only come in if it can all go out.

Have you opened up your exhaust restrictions, secondary cats, hi flow primary cats etc?

It would be good to get a dyno baseline and then open things up, add ecu tune and make adjustments so you can see if your moving in the right direction.

I noticed Pelican has an adjustable fuel regulator.
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Old 06-06-2014, 11:26 AM   #9
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I have the 4.0 bar FPR, it pulls a bit harder in the mid range, I didn't notice any different towards the redline.
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