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Discussion Starter #1
I've got a greddy fuel pressure gauge and I'm a little lost with setting up the fuel pressure on my car.

Yes this should be on a dyno, blah blah blah, but I can only do this on the road.

I've got a walbro high pressure fuel pump, nismo fpr and a godo tune map for around 400 - 420 maybe more as it was never dyno'd to full potential and the pump died.

Anyway, I've been told to idle the car, remove vac pipe on FPR, tweak until the greddy gauge reads 3.0 (100xkPa). As what I'm finding is that my idle is slightly high at 1,200rpm and when I accelerate hard its surging and missing slightly. When I accelerate it goes from 3.0 to nearly 4.0 and then when foot down it gets to 4.0 and then goes up to 5.0.

I'm guessing that this is just a simple tweak of the FPR.
 

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2.5 bar at idle 900rpm, 3 bar with vacumn off, pressure is base plus boost. 1 bar boost is 3bar + 1 bar is 4 bar minimum pressure on boost
 

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I've got a greddy fuel pressure gauge and I'm a little lost with setting up the fuel pressure on my car.

Yes this should be on a dyno, blah blah blah, but I can only do this on the road.

I've got a walbro high pressure fuel pump, nismo fpr and a godo tune map for around 400 - 420 maybe more as it was never dyno'd to full potential and the pump died.

Anyway, I've been told to idle the car, remove vac pipe on FPR, tweak until the greddy gauge reads 3.0 (100xkPa). As what I'm finding is that my idle is slightly high at 1,200rpm and when I accelerate hard its surging and missing slightly. When I accelerate it goes from 3.0 to nearly 4.0 and then when foot down it gets to 4.0 and then goes up to 5.0.

I'm guessing that this is just a simple tweak of the FPR.
fix the idle, more then likely a split vac line somewhere
 

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Discussion Starter #4
2.5 bar at idle 900rpm, 3 bar with vacumn off, pressure is base plus boost. 1 bar boost is 3bar + 1 bar is 4 bar minimum pressure on boost
I'm running 1.1 bar boost when I put the foot down controlled with an electronic boost controller.

So would that be 2.5 idle and 3.5 with boost? I can only set the FPR so do I get it to the right level on the idle and then it will be fine. Or do I get it to idle, drive and then adjust?
 

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Discussion Starter #5
I've read this on another forum.

Start your car, take the vac line off of the FPR and set it for 42-43psi. Put vac line back on.
 

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as above start car get it warmed up and set it for 3bar with the vac off to the fpr, then sort your high idle out and re-adjust if necessary

fuel pressure will rise with boost
 

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Discussion Starter #7
I tried to sort it out again today and I put 3bar on with the vac off. Then put the vac on and it dropped to around 2.25 and didn't sound healthy. So now with the vac on and idling its around 2.85. It seemed ok, I went from Darlington to Middlesbrough as the Shell here has no unleaded. Then as soon as I started on my way back, it bogged and the fuel pressure went a bit nuts, I had to drop into second and hammer it to regain it from stalling. Then it was fine. It was nearly empty and I've got a walbro uprated pump so what I'm going to do is do an earthing mod to see if that helps the pump keep up with my recent tune. Fuel pressure goes up to nearly 5bar at 1.15 bar boost on full throttle. For pump mod I'm going to cut the earth from near the right hand side of the boot and then ground it to a nearby chassis bolt this should reduce the resistance and maybe solve the problem. Would an aftermarket fuel rail help? Could this be battery related as I'm running splitfires and have had it remapped, battery is 14.2v when running does it need to be higher?
 
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get it on a dyno again for a quick run and get the fpr set up properly or at least maybe they could diagnose the problem, otherwise if you buy the rail and it does nothing youve wasted the cash as the std one is good for a hell of alot more than your asking it too same with the fpr for your state of tune its really not needed. you could end up chucking money at it buying loads of different bits that aint the problem take it to a pro mate,
 

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Discussion Starter #9
get it on a dyno again for a quick run and get the fpr set up properly or at least maybe they could diagnose the problem, otherwise if you buy the rail and it does nothing youve wasted the cash as the std one is good for a hell of alot more than your asking it too same with the fpr for your state of tune its really not needed. you could end up chucking money at it buying loads of different bits that aint the problem take it to a pro mate,
Cheers I'm going to see if local spot will run it for an hour and tweak it. I'm going to do the fuel pump earth mod and get a better battery in. FPR is just a case of turning the bolt and I can see the pressure with the greddy gauge. I just keep getting mixed levels to set it to. The a while ago had some timing changes done but since then it was tuned at the Hypertech day the other week so I can't see it being timing but who knows :) as no one seems to so far. It's just there's no Skyline places in Scarborough so will be Motoscope in Northallerton or any others that people recommend in North Yorkshire. Or Durham areas.
 
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pd tuning in boldon are good guys, not been too motorscope but there dyno has mixed reviews as far as power outputs, there used to be autosaurus in north yorks but not sure if there still in bussiness. hopefully youll get it sorted soon mate, id hate to see you chuck money at it chasing a fault and replacing things that aint broken/needed, plus another set of eyes cant help they usually see summat you may have missed.
 

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Discussion Starter #11
I'm not fused about the power out put so might just take it to which ever I can get it booked into first :)
 
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