Adjusting a fuel pressure regulator
Discussion
Hi and return greetings from England 
I have an fse on my 390, made a big difference to performance, really smoothed out the power curve too and the throttle response was much better
I have Steve Heath's maintenance manual and there is a really good description by Mark Adams on how you set the fse up.
Would you like me to scan the pages and e-mail you them separately ?
PM me your e-mail address and I will e-mail you before the end of the week.
Kind Regards
I have an fse on my 390, made a big difference to performance, really smoothed out the power curve too and the throttle response was much better
I have Steve Heath's maintenance manual and there is a really good description by Mark Adams on how you set the fse up.
Would you like me to scan the pages and e-mail you them separately ?
PM me your e-mail address and I will e-mail you before the end of the week.
Kind Regards
Hi,
thank you for your help. I have the manual from Steve Heath but I havn't really understood how the adjusting works. Now I tried it this way.
I've fitted a fuel pressure gauge at the regulator.
I remove the air cleaner to gain access to the flap, turn on the ignition an while make the fuel pump work adjust the regulator to 2.7 bar. Is this correct?
thank you for your help. I have the manual from Steve Heath but I havn't really understood how the adjusting works. Now I tried it this way.
I've fitted a fuel pressure gauge at the regulator.
I remove the air cleaner to gain access to the flap, turn on the ignition an while make the fuel pump work adjust the regulator to 2.7 bar. Is this correct?
SILICONEKID343HP said:
Bloody crude that ! I would rip the lot out and go after market . So the whole fuel table is stuck at 14.7 
Except 14.7:1 isn't the best for maximum power 
Or even the best for max economy on non cat equipped cars
Usually the fuel pressure reg is set with out a vacuum pipe attached. Then set to whatever the recommended pressure is and then see the pressure increase when the vacuum pipe is connected up again
SILICONEKID343HP said:
Bloody crude that ! I would rip the lot out and go after market . So the whole fuel table is stuck at 14.7
Except 14.7:1 isn't the best for maximum power Or even the best for max economy on non cat equipped cars
Usually the fuel pressure reg is set with out a vacuum pipe attached. Then set to whatever the recommended pressure is and then see the pressure increase when the vacuum pipe is connected up again
Fuel enrichment is provided by the ECU, as a result of inputs from the AFM and the TPS.
As per most EFI setups, it then adjusts the marked space ratio of the injector pulses to provide the necessary enrichment across the map.
My understanding, is that the rising rate FPR improves throttle response, and can provide up to 10BHP at the top end, thanks to additional enrichment.
It's quite a crude work around, but one that does seem to provide noted benefits for most people running the 4CU system.
I currently have a nasty flat-spot on mine, which I think may be a faulty FPR.
If so (I have a spare FPR to swap in) then I shall fit one the FSE 'power boost valves' and see how I get on.
As per most EFI setups, it then adjusts the marked space ratio of the injector pulses to provide the necessary enrichment across the map.
My understanding, is that the rising rate FPR improves throttle response, and can provide up to 10BHP at the top end, thanks to additional enrichment.
It's quite a crude work around, but one that does seem to provide noted benefits for most people running the 4CU system.
I currently have a nasty flat-spot on mine, which I think may be a faulty FPR.
If so (I have a spare FPR to swap in) then I shall fit one the FSE 'power boost valves' and see how I get on.
voltage_maxx said:
Fuel enrichment is provided by the ECU, as a result of inputs from the AFM and the TPS.
As per most EFI setups, it then adjusts the marked space ratio of the injector pulses to provide the necessary enrichment across the map.
My understanding, is that the rising rate FPR improves throttle response, and can provide up to 10BHP at the top end, thanks to additional enrichment.
It's quite a crude work around, but one that does seem to provide noted benefits for most people running the 4CU system.
I currently have a nasty flat-spot on mine, which I think may be a faulty FPR.
If so (I have a spare FPR to swap in) then I shall fit one the FSE 'power boost valves' and see how I get on.
So it`s throwing fuel in it does not need ,if the ECU is not doing it`s job it seems your just masking the problem . Would you be better to buy a 1:1 linea and not rising rate fuel regulator,thought he rising rate is more for forced induction .As per most EFI setups, it then adjusts the marked space ratio of the injector pulses to provide the necessary enrichment across the map.
My understanding, is that the rising rate FPR improves throttle response, and can provide up to 10BHP at the top end, thanks to additional enrichment.
It's quite a crude work around, but one that does seem to provide noted benefits for most people running the 4CU system.
I currently have a nasty flat-spot on mine, which I think may be a faulty FPR.
If so (I have a spare FPR to swap in) then I shall fit one the FSE 'power boost valves' and see how I get on.
Edited by SILICONEKID343HP on Tuesday 17th September 07:45
Daren if you think back twenty years, an aftermarket ECU was just a twinkle in the eye of some hobbyists, and those with the 4CU don't have much to play with regarding enrichmemnt, as there is no EPROM to reprogram.
So the next best thing to get more power was the rising rate regulator. This increases the relative rail pressure when the throttle is open wide, thereby improving on (working around) the original Lucas map. Rising rate regulators therefore became quite popular.
Even now, a rising rate regulator is what, 30 quid, whereas a decent emerald or likewise setup is the best part of a grand (more if you pay someone to install it).
The rising rate will give 10-15bhp, so £2-£3 per bhp. The ECU (as SportiJanne has shown) will give up to 50 bhp on a 350i. So £20-£40 per bhp depending on professional or homebrew installation.
Coupled with the fact that the rising rate can be installed and set up in about an hour, you can see why they are so attractive.
P.S. I set mine up with the engine running and vacuum pipe off and plugged, you have the correct pressure. be careful to depressurise the fuel lines before undoing any of them. Each time.
So the next best thing to get more power was the rising rate regulator. This increases the relative rail pressure when the throttle is open wide, thereby improving on (working around) the original Lucas map. Rising rate regulators therefore became quite popular.
Even now, a rising rate regulator is what, 30 quid, whereas a decent emerald or likewise setup is the best part of a grand (more if you pay someone to install it).
The rising rate will give 10-15bhp, so £2-£3 per bhp. The ECU (as SportiJanne has shown) will give up to 50 bhp on a 350i. So £20-£40 per bhp depending on professional or homebrew installation.
Coupled with the fact that the rising rate can be installed and set up in about an hour, you can see why they are so attractive.
P.S. I set mine up with the engine running and vacuum pipe off and plugged, you have the correct pressure. be careful to depressurise the fuel lines before undoing any of them. Each time.
Edited by adam quantrill on Tuesday 17th September 08:10
Surely the rising rate will knock the whole map out ,the way to do it is to use a 1:1 linear like the malpassi ,it works like the standard one but you can up the pressure slightly which will iron out the flat areas, .Rising rate regulators are for forced induction.
V8 Developments recommended this regulator.
http://www.demon-tweeks.co.uk/Product.do?method=vi...
Designed to suit modified road and competition fuel injected engines the Malpassi fuel pressure regulators operate with typical fuel enrichment as a standard regulator would. The benefit of the Malpassi regulators is that that they are adjustable and the fuel pressure at the injectors can be altered to suit the engines requirements
V8 Developments recommended this regulator.
http://www.demon-tweeks.co.uk/Product.do?method=vi...
Designed to suit modified road and competition fuel injected engines the Malpassi fuel pressure regulators operate with typical fuel enrichment as a standard regulator would. The benefit of the Malpassi regulators is that that they are adjustable and the fuel pressure at the injectors can be altered to suit the engines requirements
Edited by SILICONEKID343HP on Tuesday 17th September 17:34
Don't call me Surely!
Nah the low-end is fine, the rising rate only rises at higher manifold pressures associated with WOT (or, to be precise, lack of so much vacuum). So it works well too for the flapper system naturally aspirated.
Yes you're correct, it will work even better with a blower on there.
Nah the low-end is fine, the rising rate only rises at higher manifold pressures associated with WOT (or, to be precise, lack of so much vacuum). So it works well too for the flapper system naturally aspirated.
Yes you're correct, it will work even better with a blower on there.
adam quantrill said:
Don't call me Surely!
Nah the low-end is fine, the rising rate only rises at higher manifold pressures associated with WOT (or, to be precise, lack of so much vacuum). So it works well too for the flapper system naturally aspirated.
Yes you're correct, it will work even better with a blower on there.
Why does the 14cux work better with the adjustable 1:1 not rising rate.Nah the low-end is fine, the rising rate only rises at higher manifold pressures associated with WOT (or, to be precise, lack of so much vacuum). So it works well too for the flapper system naturally aspirated.
Yes you're correct, it will work even better with a blower on there.
Hi,
thank you Adam for your advice. I tried it this way and adjusted pressure to 2.7 bar at idle speed. When I reconnect the vakuum pipe I get about 1.9 bar system pressure. That´s exactly the value with the standard regulator. There is no effect. When I increase the value to 2.7 bar at idle speed with vakuum pipe connected (system pressure abou 3.2 bar) I get a significant better acceleration and throttle response. The question is how high can I increase pressure without damaging the engine?
Greetings
Bernd
thank you Adam for your advice. I tried it this way and adjusted pressure to 2.7 bar at idle speed. When I reconnect the vakuum pipe I get about 1.9 bar system pressure. That´s exactly the value with the standard regulator. There is no effect. When I increase the value to 2.7 bar at idle speed with vakuum pipe connected (system pressure abou 3.2 bar) I get a significant better acceleration and throttle response. The question is how high can I increase pressure without damaging the engine?
Greetings
Bernd
The engine cannae tak'it cap'n!!!!
Sounds like you are spot on so far (can you see how it's supposed to work now Darren?)
Well if you increase the pressure all round you'll be running more rich. I don't think you'll damage much but the plugs will start to soot up and and some point the optimum power AFR will be passed and you'll lose power. Some time before that the economy will suffer badly. So you'll go faster - to the next petrol station!
Also if you are on the rich side that leaves no room for manouver in case the engine temperature sensor isn't spot on and it'll run far too rich if the transducer reads the wrong temperature back.
Sounds like you are spot on so far (can you see how it's supposed to work now Darren?)
Well if you increase the pressure all round you'll be running more rich. I don't think you'll damage much but the plugs will start to soot up and and some point the optimum power AFR will be passed and you'll lose power. Some time before that the economy will suffer badly. So you'll go faster - to the next petrol station!
Also if you are on the rich side that leaves no room for manouver in case the engine temperature sensor isn't spot on and it'll run far too rich if the transducer reads the wrong temperature back.
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