por9146gt

I changed the chip in my track car,and It ran real rich. hesitating and black smoke at 4000. on the dyno, it was rich off scale on the wide O2. i lowered the pressure to 24 psi to get the high end 45-6500 into the 12/1 ratio and gained 35 horsepower this was also the only way to read the mixture throughout the rpm range. I want to send the chips back with dyno results to reprogram. what is the best way to approach this. if I turn the press to 3 bar i cant get a good graph for them to look at. ahy help is appreciated.

fast951

Shouldn't be very hard.

You know your injector flow at a preset Fuel Pressure. You know the Fuel Pressure where your car got good AFR. They should be able to figure out the needed changes based on this...
My guess would be that they have to lean it 35-45%.

por9146gt

Great thanks for the info fast 951, just want to make sure it is done correctly so i can move on to something else.

Ski

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by por9146gt:
<strong>i lowered the pressure to 24 psi to get the high end 45-6500 into the 12/1 ratio and gained 35 horsepower</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Funny,,,when I cleaned up my A/F ratio I gained 32hp. Glad to see someone else got similar results!

Danno

The other thing you want to keep an eye on is the shape of the air-fuel curve. Especially at high-RPM, it should flat without getting leaner and leaner.

por9146gt

That was the interesting thing, there was a spike real rich at 3500 (more than 10/1), then at 4200 at my peak torque reading a spike to 17.5/1 after that is settled all the way to redline at 12.25/1...I am aiming to get those spikes out, and run the car at the 3 bar.

fast951

17.5:1 under load is a NO-NO-NO. Get it checked/fixed before you do any additional runs..

por9146gt

yup, took the chips out and sent them off already. Now if they reprogram them and do it for 3 bar, I will take it back and run it again..and probably have them fine tune them one more time.