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R34 GTR fuel delivery issue

Deza3000

By Deza3000,
in Engines & Forced Induction

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Deza3000 Proficient

Deza3000

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R34 GTR fuel delivery issue

Hi Guys,

Got a bit of an issue with the fuel delivery on my car and was wondering if you can help me out...

Just a quick background on the car:

- Brand new 1000cc xspurt injectors with resistor pack removed
- Brand new walbro 460lph e85 fuel pump with relay
- Apexi powerfc
- 2860-5 turbos
- titanium turbo back exhaust
- ARC intake (stock afms)
- manual boost controller - set to 18psi


I got my car tuned today only to find out the car was only able to make 290awkw on e85 @18psi safely. I was aiming for 350-380awkw however my tuner said the car struggled to go above 290 due to the car leaning out. Apparently he had to trick the ecu into thinking the injectors were only 550cc in order to get the car running right, where as when they were set to 1000 it would just run lean. He was reluctant to up the boost for obvious reasons. Im taking the car back to one of the boys who used to work at racepace to do a check on Monday (he was the one who installed all the parts for me), however this is something ill definitely be losing sleep over during the weekend. Just wondering what everyones opinion on the issue would be? 

Only thing i could think of was that the injectors dont like the ecu or the fuel filter in the engine bay is dirt. 
 

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https://www.sau.com.au/forums/topic/469402-r34-gtr-fuel-delivery-issue/
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Deza3000 Proficient

Deza3000

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I dont quite remember what he said but apparently its wired through a relay and the earth wire is grounded so it doesnt vary the voltage or something along those lines... im not a sparky so i didnt quite understand what he meant haha. 

KiwiRS4T Grand Master

KiwiRS4T

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Pull the fuel line off the rail and hotwire the relay so the pump doesn't stop and measure how much it is actually pumping. FPR shouldn't be a factor at WOT unless its shagged. Sure your tuner knows what he is doing?

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Deza3000 Proficient

Deza3000

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17 hours ago, KiwiRS4T said:

Pull the fuel line off the rail and hotwire the relay so the pump doesn't stop and measure how much it is actually pumping. FPR shouldn't be a factor at WOT unless its shagged. Sure your tuner knows what he is doing?

Will give this a try. Im pretty sure he said it was leaning out as soon as it came on boost when it was set to 1000cc, maybe the FPR is shagged. Yea the tuner is well known, he's done quite a few GTRs on flex tune and straight e85. 

 

 

9 hours ago, morehp2go said:

How long have you been running e85 and have you changed out all the old rubber lines and is it a stock filter? If so piss it off to some thing a little more flowing

1 day... all the mods listed in the op were also installed at once during the week, before that the whole car was stock apart from a mbc. This was my first official tune for my GTR, for all i know it might be an underlying problem. 

admS15 Grand Master

admS15

Posted
Posted

I had a similar situation with the injector size change in the ecu settings, wouldn't run properly unless set to smaller size. Ended up being a tired fuel pump. In your case, pump is new, so as said above, change fuel filter and check fp wiring and for kinked or swollen fuel lines. Particularly in tank.

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Deza3000 Proficient

Deza3000

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Update:

So it turns out it was the fuel filter, it was old and clogged. 

The workshop also found that one of the airflow meters are reading a little funny, so they swapped that out. They said the car is still running a bit iffy (dont know what they meant by that), so they are swapping out the power fc with another one to see if it fixes the issue. The good news is they also did a compression test which was 175 across all 6 cylinders, pretty happy with that :D

Deza3000 Proficient

Deza3000

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Got the car back today, now its running super rich meaning its ready for a re-tune. A few things were changed:
- fuel hoses
- fuel pressure regulator
- injectors flow tested - all 100%
- fuel filter (absolute filth apparently)
- Fuel tank cleaned, very dirty from suspected fuel staying in the tank for long period, the e85 probably diluted it  (id imagine it was sitting at the auctions for more than a year)

Things to change:
Spark plugs - they still had the denso plugs in there, had white corrosion all over, looked crusty, either it was swapped using the oem parts or it was never changed in its life. 

Which leads me to my next question, what plugs and what gap do you recommend? I was thinking of getting  BCPR6ES gapped to 1.1 ?
It will be tuned to ~24psi on e85 hopefully...whatever the tuner thinks is safe 
Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

From my experience, with casual tuning experience I found with iridium plugs you're able to run a slightly bigger gap than coppers.

I only tried this out when Mark at MRC told me he combats misfires by throwing in iridium plugs. Funny enough I had a SR20 with big boost suffering from spark break down with about 1.8bar going through the motor. I had the plugs gapped to 0.5mm and it was still missing at peak torque.

2nd time round on the dyno, I told the owner to throw in iridums and gap them to 0.6mm, no misfires. 

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