HI!

After a few modifications, I wanted to set the Co value according
to the software specification (2,5% at idle, stage 3 with original
Turbocharger).
So I went to a garage waited until the engine was hot and started
to measuring the exhaust gases.
At idle the car had ~8% Co (Lambda ~0,75). When I made some
adjustments on the Co screw on the ECU there where just minor
changes but there was no chance to reach the needed 2,5%.

The car is a 4*4 Sierra green top with closed loop. Is it anyhow
possible to change the Co value on a car which is O2 sensor controlled?
I thought the o2 sensor will try everything to keep the value at
1 until you reach a defined level of boost...

Maybe someone can give me some support?

Thanks!!!

 

Exactly that is the point!!
The CO is lamda controlled so software(chip/setting) wil keep it at lamda 1.
tabetha

 

Hi Tabetha!

So there is no chance for me to adjust the CO Level?
How will I know that the car runs as it should on full boost
(Lambda ~0,85)?
Is it enough to check the color of the sparking plugs?

 

Forget about checking plug colour, best bet is to have it run on a rolling road to know for sure, that it is running right and not going to melt.
tabetha

 

the co will be able to be adjusted slightly at idle, but only slighly,

the main thing you want to check is the fuelling outside of the closed loop parameter. depending on software, remember when you adjust the global fuel adjuster, you are adjusting a percentage of the whole map, so it will also make changes to the top aswell as the botttom, so it needs wideband or dyno checking to make sure it doesnt run weak/rich at the top afterwards.

 

HI!

Okay so here is my summary:

1.) There is no possibility to make big modifcations
on the CO value on a Cosworth with closed loop lambda control.

2.) Lambda value has to be checked at full power (dyno or
with a wideband O2 sensor on the road.

So what shall I do if I make a wideband measurement and find
out that the car is running to lean?
Do I have to increase the fuel pressure because CO adjustment
is not possible?

 

if it is to lean at the top, make adjustments to the global modifier.

it shouldnt be to lean at idle, as the co should level out at between .5 and 1.0%, small adjutmants can be made via the global fuel adjuster, but it should be checked at the top before deciding it is ok.... im sure stu recommmends it sits at around .90% at idle, which for me was two turns rich.

the fuelling at top is more important than idle.

never adjust fuel pressure.

in reality ,if your runing MSD software ,you have some of the best there is ,so there shouldnt be a problem, any doubt ask MSD as they will guide you through the set up.

 

I´m running the MSD software and the car performs fantastic!

According to the setup guide, the CO value should be 2,5-2,7%
at idle so I was thinking I will be able to adjust the value with
the CO screw on the ECU.

 

2.5-2.7% is the setting for non closed loop cars ring msd give them your chip number and check mate, im sure its 0.90 for closed loop.

the adjuster on the ecu is the global modifier

 

i am not sure that the closed loop work at idle

stu where are you ?

 

HI!

What do you mean with "the adjuster on the ecu is the global modifier ".
What can be adjusted there?

 

on the ecu , you have a white screw, on the right. if you turn it, you change de CO, but not only at idle ....

Stu explain the settings on the paper with his chips

 

closed loop does work at idle depending on how stu has set it.

 

Yup it does - made a HUGE difference to my mates car that was running greys. I'd have closed loop in a flash if it fitted my super 8

 

The chip you have bought there is NOT closed loop mate, so 2.5 - 3% CO is fine.

 

does the closed loop run at idle ?

 

Yes pal. As long as engine is hot.

 

L8 ECU can use chip without closed loop?
At this case he can turn off lamda sensor?

 

Correct.

 

HI!

Are there any other disadvantages except the higher fuel consumption
on the non closed loop system?

 

so, what kind of AFR value should be show on the gauge at idle ????

14.7 ????

 

Lambda 1 = AFR 14,7 has to be shown when you are running
a closed loop system and the engine has finished with the warm up phase.

 

my question was at idle!!!

 

14,7 at idle.
The value will be AFR 14,7 from idle up to a defined boost and throttle angel.

 

on the paper with the chip, STU said something else if i remenber, i will check