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MG MGF Technical - running lean

my vvc is apparently running lean due to its breathing mods. Is it possible to adjust this without remapping the chip? Presumably Im losing a bit of power if it is running lean?
marc hanson

What mods have you done Marc? An adjustable fuel regulator might be what you need. If the engine is running lean it will lose some power but more importantly it will create more heat in the cylinder head probably not recomended.
Blue Pocket Rocket

How do you know its running lean?
Steve Ratledge

And how lean is 'lean'?

If you're looking for a sprint championship friendly modification Marc, I may have just the thing for you - but I'd recommend that the car is put back onto a RR for a repeat Lambda check once it is fitted :o)
Rob Bell

thanks rob. the last rr test i did allegedly showed it running lean at "4%" (whatever the hell that means!)could i boost the fuel pressure to compensate for the bigger filter / TB?
marc hanson

Do you have the air fuel mixture data printed out Marc? If so, show me next time I see you. As it happens, I have a FPR that has been squeezed a little to increase the rating from 3.0 to 3.3 bar. This is a little rich for my car, so is sitting in a box in a cupboard somewhere gathering dust... ;o)But it may be too much for your too: from Davbe's, Paul's and Thierry's experience, you need to seriously increase head breathing before uprating the FPR brings any serious benefits...
Rob Bell

hmm thanks r. Im going to get the car rerun on the southern carburettor rr shortly and i'll see what they come up with. doesnt sound like theres much i can do. i'll bring the data when I next see you. first mgcc event im doing is longcross in april. are you going? my first event is at north weald this sunday. bit early in the year so hope it stays nice!
marc hanson

I have Longcross pencilled in in my diary Marc - but not yet recieved the regs - have you?
Rob Bell

>the last rr test i did allegedly showed it running lean at "4%"

Compared with? 14:1 max economy or 12:1 max power? (numbers from memory may be out by 1)
Will Munns

rob - got the regs for longcross a while ago as im in the sutton and cheam motor club. you should be able to get them via their website. last i heard they had over 100 entries already so i fear you may be too late.

will, i have no idea!
marc hanson

Around 13:1 is the figure that seems to give the best results for the K-series. I wonder what figures Southern Carbs will show?

Regarding Longcross - thanks for the heads up there - I'll see what can be sorted!
Rob Bell

I've never seen or worked on an mgf, but if you are simply looking at a scanner data, that 4% most likely means fuel compensation %, not fuel mixture. As your engine wears or changes from new, your computer will adjust and compensate as much as it can in order to maintain the correct fuel ratio. In, other words, if you made some changes that make your engine need more fuel the ecm will add a certain % by opening your injector longer. Usually, +- 20% is the most computers are designed to compensate before turning on a warning lamp. At least that's how it works here. Good luck.
joaquin

This thread was discussed between 11/03/2005 and 16/03/2005

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