MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - Power boost valve adjustment

Hi
I recently fitted a FSE Power Boost Valve (PBV) to my MGF VVC. So far I have not adjusted the valve but I'm wondering whether I should try and increase the fuel pressure by adjusting the PBV. Has anybody done this before and what did you experience?

Regards
Beat Fischer, Switzerland
Beat

Having read the instructions for one of these (thats all the experience i have, not fitted yet) it says not to increase it to much or the increased pressure will put strain on the fuel lines and not a lot else.
Matt

The fuel pipes should be able to deal with many times more pressure than the fuel pump is capable of generating.

Simply winding up the fuel pressure will result in lower economy, a knackered catalytic converter, rough idle and less power.

Mike
Mike Bees

I fited a FSE Power Boost valve to my F about 5 months ago and left the valve as it was as I was happy with the performance. Unfortunately I've had to take my car in to Rover last weekend with suspected head gasket problem only to find out that the valve liner on one pot had cracked (new engine job...gulp).My car is not yet 3 years old and only 23k. Rover have not mentioned anything about the PBV and I am not going to bring there attention to it. I am unaware if the PBV could cause this kind of damage. Any Tech Heads out there with coments would be appreciated.
Rob Marsh

Rob,

That sort of damage is not something that an over rich mixture would cause. Bore wash (excess petrol washing the oil film from the bore walls) is a possibility and this results in wipe out piston rings in double quick time and a sump full of petrol/oil mixture.

This adds to Mike Bees observations.

Rog
Roger Parker

So, I wonder what the correct answer to Beat's question is then- ie how to correctly adjust the PBV to provide optimum performance without any of the detrimental effects that Mike and Roger mention?

Sounds to me like a rolling road session in a facility that also has an exhaust gas analyser...
Rob Bell


Hi all,

the way I did it was as follows : Due to the fact that the MEMS unit when out of lamda-loop put in a preset voltage my ordinary lamda-sensor tappoint was of no use. So one has to use a second free-standing unit that measures the actual lambda number. This will be a bit akward if the cat is fitted during the test as there is no access . Of course this can be fixed by drilling for a second lambda-sonde and after the test blind this outlet. (Same thread as ordinary spark plugs !) So a cat-bypass and a heated lambdasonde in the exhhaust where the outer casing still can see free air is the way to go. I had at that time no access to a rolling road so I made the test when doing ordinary driving.. To my surprise the FSE-valve seemed perfectly well calibrated. Quick on/off readings centered around lambda 1 at any "normal" driving and quickly changing to fatter mixture at any acceleration. Lambda voltage then around 1,27 V and fuel/air around 13,5. Unfortunatly no test was made on the old bog standard system but my impression is that the slight hesitation at lower revs was totally gone.
As I now have the big-bore throttle I think it is time for another check to see if the valve needs re-adjusting. But this has to wait until spring as the "Green Frog" is on stands for the winter.


Regards , Carl.
Carl

Beat,
just found, who you are :))....
Recommend to foreward and discuss Carls explanation with Nikolaj at the german Forum (MGF Technik) as well if he doesn' appear here.
Nikolaj has the same setup as Carl now at his car with the GM throttle body.

Cheers
Dieter
Dieter

Beat/Rob Marsh,
what type of hose did your PBV come with? I ordered form Moss. From their website they show the PBV together with a steel-braided hose but on delivery, they supply it with a rubber hose. On enquiry, they say they don't have the s-b hose in stock.
Jason

Jason

The PBV came with rubber hoses, I also ordered from Moss. No problem for me or even better. I wouldn't like to shorten steel braided hoses...

Regards
Beat
Beat Fischer

Beat,
have a feel at the rubber hose to the PBV with the engine started. Then rev the engine. You can feel the rubber hose expanding/hardens as fuel flows thru it. In time, the rubber hose could get soft. I'm afraid the hose may leak 1 of these days.

Jason

This thread was discussed between 16/10/2001 and 24/10/2001

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.