29 replies to this topic

[Ruckus]

not neccessarily, its depends how your engines runnning, mine seems to be running slightly lean from my maniflow system...which means a fuel pressure regulator will work well, go to minisport minispares and type in power boost valve(goochy name for fuel pressure regulator) the gauge can be bought seperate.

None of them look adjustable, just a fixed unknown presure?

[jamesmpi]

not neccessarily, its depends how your engines runnning, mine seems to be running slightly lean from my maniflow system...which means a fuel pressure regulator will work well, go to minisport minispares and type in power boost valve(goochy name for fuel pressure regulator) the gauge can be bought seperate.

None of them look adjustable, just a fixed unknown presure?

Have a read of this. Maybe helpful??

http://www.mgf.ultim...l_regulator.htm

[Ruckus]

 

 

not neccessarily, its depends how your engines runnning, mine seems to be running slightly lean from my maniflow system...which means a fuel pressure regulator will work well, go to minisport minispares and type in power boost valve(goochy name for fuel pressure regulator) the gauge can be bought seperate.

None of them look adjustable, just a fixed unknown presure?

Have a read of this. Maybe helpful??

http://www.mgf.ultim...l_regulator.htm

 

You ledge mate, none of the mini part site's that sell these say they are adjustable :)

 

cheers

 

Ruckus=skooled

Edited by Ruckus, 16 August 2014 - 10:24 PM.

[jamesmpi]

:) no problems

[jamesmpi]

I've got mine set to 3.2 bar which is a constant pressure. Looking at the info on link it is simply not the case of wanging up the pressure to give better performance. Ideally you need it setup on a RR but somewhere around 3.2 bar should be ok

[Ruckus]

I've got mine set to 3.2 bar which is a constant pressure. Looking at the info on link it is simply not the case of wanging up the pressure to give better performance. Ideally you need it setup on a RR but somewhere around 3.2 bar should be ok

 

Does it not say that at idle its only 0.5 then moves up as the vacuum rises?

Edited by Ruckus, 16 August 2014 - 10:26 PM.

[jamesmpi]

Yes that's right. I meant that when driving under load it will reach a set pressure.

Some people think it works a boost valve for a turbo where you can quickly increase/decrease the pressure.
With the FPR once you find the optimum pressure you just leave it at that pressure

[Ruckus]

But its not full pressure all the time only under load. does that mean in the lower rev where there is less vacuum the pressure is not the full 3.2 (if that's whats its set to).

 

I still worry that it will be over rich down low, where currently its perfect.

[jamesmpi]

I believe so. There must be a vacuum for it to work correctly, and the pressure varies between 0 and set limit (e.g. 3.2 bar) but it won't exceed the limit no matter how hard you push the throttle.

I'm not an expert with this, the knowledge I have is based on the info that I have read and from trial and error

There seems to be wide acknowledgement that modified mpis (both minis and MGs) suffer with lean fueling at top end and this seems to be the only option to help stabilise and even out the flow rate across the rev range.

I haven't noticed any major draw backs regarding mpg. Although I did plumb it in round the wrong way once meaning unused fuel wasn't being returned to tank. This was causing black spots to be blown out my exhaust from over fueling. Don't think my CAT or lambda liked that either but I've corrected it now and all seems well

Edited by jamesmpi, 17 August 2014 - 04:07 PM.

[jamesmpi]

Extract from my link above

Typically, the regulator (here they are referring to the standard regulator on your fuel rail) is not adjustable (it isn't on the MG Rover fuel rail found on MPi K-series engines) and is pre-set to a 3.0 bar maximum pressure - with a tolerance of 0.2 bar. This is not, however, a fixed pressure, as there is also control of fuel pressure dictated by inlet manifold vacuum (inlet manifold vacuum increases when the throttle is opened and the engine speed accelerates, and is practically zero at engine idle). Thus, at idle, the FPR opens at a value 0.5 bar lower at approximately 2.5 bar. When accelerating quickly from standstill (increased inlet manifold vacuum), the fuel pressure increases at a proportional rate - retaining a relatively lean fuel mixture strength as required by E.E.C. emission regulations for new vehicles

Edited by jamesmpi, 17 August 2014 - 04:14 PM.

[Steve220]

What the quote basically is saying is it isn't a very good system. An adjustable fuel pressure regulator HAS to be set up properly on a rolling road with an emissions probe attached to the inside of the exhaust pipe. You have no other way of knowing if your car is running lean unless you have a Exhaust temp gauge. I'm surprised MEMS doesn't fuel for your top end as it does on the K series. Seeing as they're the same basic modular programming i'm struggling to understand why it doesn't.

 

Never crush a fuel pressure regulator, you will never know how much pressure it will be supplying or whether or not you've crushed the internals so much that it stops working altogether and over fuels your car to the point it does this through over fuelling (taken from my old engine as the previous owner knew nothing about proper fuel management and set up)

 

 

You always measure a fuel pressure on an adjustable regulator with the vacuum feed detached on idle and adjust accordingly back to 3bar. On a naturally aspirated car i'd never go over the recommended fuel pressure as the increased fueling will cause bore wash during mid RPM range and will eventually kill the engine. You have to ask yourself - How many times do i go to the redline on my engine? If its utterly minimal (ie only when you're accelerating hard a few times) then getting the mixture to be right at high end Vs mid range, i'd rather it be lean at top end and the exhaust temp be hot for a few seconds before the engine cool for mid range work.

 

Just my 2p of course.

Steve

Edited by Steve220, 19 August 2014 - 10:39 AM.

[Ruckus]

What the quote basically is saying is it isn't a very good system. An adjustable fuel pressure regulator HAS to be set up properly on a rolling road with an emissions probe attached to the inside of the exhaust pipe. You have no other way of knowing if your car is running lean unless you have a Exhaust temp gauge. I'm surprised MEMS doesn't fuel for your top end as it does on the K series. Seeing as they're the same basic modular programming i'm struggling to understand why it doesn't.
 
Never crush a fuel pressure regulator, you will never know how much pressure it will be supplying or whether or not you've crushed the internals so much that it stops working altogether and over fuels your car to the point it does this through over fuelling (taken from my old engine as the previous owner knew nothing about proper fuel management and set up)
 

 
You always measure a fuel pressure on an adjustable regulator with the vacuum feed detached on idle and adjust accordingly back to 3bar. On a naturally aspirated car i'd never go over the recommended fuel pressure as the increased fueling will cause bore wash during mid RPM range and will eventually kill the engine. You have to ask yourself - How many times do i go to the redline on my engine? If its utterly minimal (ie only when you're accelerating hard a few times) then getting the mixture to be right at high end Vs mid range, i'd rather it be lean at top end and the exhaust temp be hot for a few seconds before the engine cool for mid range work.
 
Just my 2p of course.
Steve

This is how I saw it to be honest, but then they put one in the Cooper conversion kit. Would they really put something in that can over fuel so baddly it will wash the bores?

[Ruckus]

Oh and you can feel it hit the lean over 5k it just runs out of puff.
A guy on here with the same mods as mind posted RR plots and you could see it go to **** after 5k. He fitted the SC injection system which have him +20bhp and good pull all the way to the redline.

I think the problem is the window for the stock injectors and fueling system is too small to get enough fuel in in time.

I would like to think with a slightly higher fuel pressure the MEMS system would see the higher fuel rate and in the lower revs not fire the injectors for so long, but I don't know if the system is that clever?

[Steve220]

I'd have to see the A/F ratio throughout the rev range to get a full understanding of what mems is trying to do. Definitely an interesting subject!

[sirjakethebrit]

I have the kit waiting to go on my spi. Did your alarm and immobiliser still work when fitting sc kit?

No mate it doesn't, could do with sorting an aftermarket item really. But it never gets left anywhere so I'm not too fussed to be honest