ThomasV

Running a MSD stage 3 sapphire 2WD.

Measured fuel pressure with gauge and it was 2,8-3 bar on idle when warm at approx 900-950 rpms.
With hose off fuel pressure regulator it was approx 3,5 bar.

When driving on the road the fuel pressure rose to approx 4,5 bar with 1 bar of boost pressure and just under 5 bar with 1,4-1,5 bar of boost pressure.

Is this correct ??

Cheers
Thomas

James @ M Developments.

iTrader: (2)

yes pretty much spot on.

ThomasV

Fabolous! ... thanx James!

Cheers

ThomasV

Also had the car at a MOT station today to get the Co level set and I'm quite surprised as to how hard that actually is to set properly.

Car is set @ 900-1000 rpm idle and all electronics are switched off.
It then read between 2,2 and 2,8% .... is it normal that the measure differs up and down like that ? ...and when the radiator fans kick in, it drops way down!

I was afraid it would run a bit lean since MSD says 2,5-2,7% so I adjusted the screw so that it measured between 2,7-3.2% instead. Rather have it run a little bit rich than risk anything, when an actual precise measure was so hard.

I guess a rolling road session with AFR measure is only way to make sure, that it doesn't run lean at higher RPMS and when on full boost.

James @ M Developments.

iTrader: (2)

yes, you really need a on load fuelling check, as the idle has little relivance to it when its under load, your idle fuelling will be fine as it is.

ThomasV

Yes, that is definately the next step.

Thanks James.
And by the way ... can't fault the MSD chip. It really works great. Car drives nice and smooth off boost and pulls even and amazing on boost. Couldn't ask for more.

Cheers!

ThomasV

Now that we are on the subject ... I would actually like to know how the chip/ecu/fuel actually works.

The chip contains (among alot of other data) the fuelling information for the entire rev range and I am then able to adjust the fuelling a little bit by adjusting the Co screw clock/counter-clockwise, is this correct ?

In other words ... if I strap the car on rollers and it runs lean in the top-end of the rev range, it is down to the chip and not the Co screw adjustment ... correct ?

James @ M Developments.

iTrader: (2)

The co screw is a global modifier, and adds or subtracts a percentage to the whole fuel table,

but adding 10% at idle will be much more noticeable than adding 10% on the top line.

ThomasV

Ok ... that makes sense. I will leave it where it is now, and then I can adjust the Co screw on the rollers, should the car runs rich or lean further up the rpms .... but doubt it. It's a MSD chip.

Thanks alot James. Appreciate it, mate!

florent78

iTrader: (1)

this is true for partial throttle position
but when you've got full throttle, the CO value do not change the fuel injection value


is it correct ?