pee vee

hi!

IF a cosworth has been Set to run 3.5% at idle, should it be correct right thru the range?
i am just reading something that does NOT appear to have been written
very well, and seems to suggest that if its right at idle, it would be fine
thru the whole load/rev range?

I guess this would depend on the mapper/chip used?

as the CO2 adjustment screw on the ECUs effects the 'global' fuel
rather than just the idle C02?

just trying to understand a bit more about it all really!

cheers!
P

PS: no im not about to start fookin about with mine lol

foreigneRS

no, not necessarily. you understanding is correct, it depends on the rest of the map

xurrita

I think that the cosworth co2 is 1,5% in all cosworth stage 1 stage 2 and the original! ?

pee vee

mine passed the MOT at 3.5% the other week i think?

thinking about it though, its obviously gonna be impossible for anyone
to say what it is!
some mappers might make it slightly rich at the top
for fear of a melt-down (in their name! lol)
others may not.

JjCoDeX75

I am pretty sure that the Co adjust on the ecu is only for idle speed, and has absolutely nothing to do with the rest of the map as far as I know.

If you are concerned about leaning off, you could either fit a lambda sensor and gauge, or else get on rollers. They will check the co always through the rev range.

Only slight word of warning - I put an air fuel ratio meter on mine, and it is completely useless after a good thrashing. I think the sensor overheats!

Hope this helps!!

Stu @ M Developments

iTrader: (12)

CO screw is a global multiplyer and adjusts the entire map.

The fact the co is correct at idle is entirely irrelevant to anything other than an idle emissions test and CERTIANLY is no indication of engine safety or efficiency,.

DazC

iTrader: (1)

Just to confuse matters, CO2 emissions should be around 16% ish at idle!

svony

iTrader: (3)

So although the CO2 has been set to the recommended level at idle it will most likely need to be further adjust on the rollers across the full RPM/load range? wont that affect the idle CO2? (higher?).

I've set my CO2 to 3% based on the mappers' recommendation but I have not being able to get to the rollers as yet. Looking at the spark plugs it looks like the car is running a bit rich at idle but seems fine under boost (14psi) with no sign of deonation.

sailorbob

Seems an odd thing to do, why didn't they ignore the input from the CO screw when going into open loop? Is it a quirk of the Weber Marelli system?

DazC

iTrader: (1)

Your car won't run at 3% CO2!!!

Stu @ M Developments

iTrader: (12)

95% of cars out there on Weber Marelli dont have any closed loop feedback. It wasnt available until late 91. The CO screw simply adds/subtracts from the base fuel map from its central point. It has an adjustment range of approx +-125. All mapping and development should be done with the screw centralised thus a car will need a slight trim either way to fuel perfectly.

The fact is, the data on the chip wont change, and if you have reputable software it will have been tested and developed to do what its supposed to do with an idle emissions figure of "X".

If she is lean on boost with the emissions set as per instructions, dont fook around with the co screw, find out whats acually wrong..

Fuel reg.
Pipework to regs and sensors.
Fuel Pump.
Fuel Pump wiring.
Fuel Filter.
ACT sensor.
Map sensor.
Engine spec change.
Some goon jacked her up on the fuel lines.
The list is endless... but the CO screw wont stop her melting down so stop looking for an easy fix and get her fixed properly.