wintn

I fitted a high capacity fuel pump (Prodrive) to my UK 99MY and noticed a huge improvement in response and power. I have VF24, full decat and manual boost control set to 1.1/1.2.
Then within a few miles the performance fell off, the AFR showed weak fluctuating mixture, started getting a lot of Knocklink activity and fuel consumption improved (commuting, from 21 to 23).
Checked the fuel pressure at idle and it was 2.2 bar with vac pipe connected and 2.8 disconnected - bit high maybe. Could not check on-boost fuel pressure at that time.
Problem has got worse (occasional red/amber light on AFR, no green or blue).
Temporarily fitted the fuel pressure guage inside the car (long pipe) and the results now are:
idle 3.3bar with vac pipe on (-0.6 bar on boost guage), 3.6 with pipe off.
At 0.9 bar boost fuel pressure is 4.25 bar.
When the engine is turned off fuel pressure falls to 2.2 and remains there (residual pressure in system).

It seems to me that the regulator is knackered or possible overwhelmed by the pump.
From other threads on this forum idle fuel pressure should be 2.8 (pipe disconnected) rising with boost pressure, so at 0.9bar boost should be 3.7, a rise of 0.9bar.
Mine only seems to rise by about half of the boost pressure rise, but is already higher than normal.

I guess I need a new regulator?
What would be best, a replacement standard or an aftermarket adjustable, and which one?

jonny gav

iTrader: (1)

looks to me like you have found the problem, an SX regulator seems to be the best choice as the FSE ones seem to have a problem with holding pressure.

best place i have found for price is AS-PERFORMANCE.

give alyn a ring on 0191 4103770 he should be able to sort you out with what you need.

do you have any more info on the pump you have fitted???

wintn

Thanks Jonny,

I have tried 2 pumps (long story), firstly a Henko 255 l/min, then after the problems started a 'Prodrive uprated' (no more info - has soft rubber cover over body and came in Prodrive box) which the later pressure readings were taken with.

wintn

But if the pressure at 0.9bar boost was 4.25 and it should be 3.7 why was the engine running weak?

jonny gav

iTrader: (1)

good question, it shouldn't be showing lean if the pressure is above and holding.

i take it you have a dawes AFR???

i have had a few probs with afr's showing lean when in fact there was a fault with the lambda sensor.

have a check over the wiring of you AFR first to make sure there are no problems.

i have had 2 lamda sensors go like this, the first time i was lucky as i had a spare one in the garage, when i fitted it all was well.

P20SPD

iTrader: (1)

Surely if its 3.6 with the vacuum pipe off, ie atmospheric pressure, then at 0.9bar it should be at 4.5bar fuel pressure.

Have you altered the anything in the ecu to cover the change of turbo re fuelling?

SX reg is what i would use as a replacement, as the standard regs are prone to being overpowered by uprated pumps.

69WRX

wintn.

What problems did you have with the HENKO fuel pump ?

I have had one of these on the car for a couple of months now and all seems fine.

Andy

wintn

Thanks Jonny
Yes it is a Dawes. Seems to read 'normally' at idle/low speed, also apparent lean is acconpanied by knocklink activity I did not have before.
Still, I will check wiring, interesting you have had lambda failures - how did you suss out the problem?

wintn

Did not have a problem, happened to have a Prodrive so swopped to see if there was any difference.
Will probably refit the Henko when problem is sorted.

wintn

Agree it should go to 4.5bar, but it does not!

I have an SX on its way - lot of money, I hope it cures the problem.

I have an 2.5 ECU fitted which is now obviously not optimum. Waiting to fit new clutch (done today) and Gruppe s headers (waiting in the garage) before getting a remap.

jonny gav

iTrader: (1)

trial and error, i had the lambda and had heard of it happening before to others so thought i would swap it over to see.

what size injectors are you running???

wintn

440cc - standard MY99. Should be OK

wintn

Seem to be getting there, found 3 problems so far!

Replaced the reg with an SX and set idle pressure to recommended 2. with vac pipe on. Car ran OK but no AFR lights except occasionally at idle! Took Jonny gav's advice (thanks Jonny) and changed the Lambda sensor (universal, £41 from local factor). Sensor now working above idle but only got AFR lights up above 6500 rpm (Dawes AFR). Had to increase idle pressure to 2.6 to get green/blue lights across the whole boost range as I did from standard. 2.6 bar was what my original standard reg was set to before it went wrong, does the 99MY UK have a higher fuel pressure?

As this was going on I lost the Knocklink - no lights at all. Checked the LEDs and had to re-solder 3 which had come loose. Knocklink worked but took it apart again and now it does not work (started another thread on that).

Then felt confident enough to look into why I could get no higher than 0.9bar boost with the MBC despite keeping on turning it up. Found a piece of crud on the valve causing a leak. Cleaned the valve and put the MBC back on and now have 1.2bar and car goes well.

Still have to fix the Knocklink (not thrashing it till I do).

jonny gav

iTrader: (1)

glad you got to the bottom of it