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      10-03-2012, 05:44 PM   #54
Mike Benvo
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Drives: Harrop SC M3 / E46 M3 / 7Turbo
Join Date: Apr 2008
Location: SoCal

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Quote:
Originally Posted by Sal@Evolve View Post
Benvo!

Love it when you get all technical!

Serious note - you are completely correct here with respect to the fuel factor table and lambda aims.

The lambda will aim to what ever you set it - but it can only aim so much.

If the fuel factor table (10x10 fuel side) map is not altered correctly and the fuel scaling factor is not calculated correctly with respect to the size of the injectors then the aim will always be aiming but never achieving because the deviation is simply too large.

Our own supercharged car has been tested in 0 degC, 5-8 degC and 25+ degC. Our aim is 12.2 AFR. We achieve very close to it what ever the ambient temperature is (there is a limit where physics will take over but they are big). The reason is because the fuel scaling and fuel factor table has been correctly set which is derived from continual testing and retesting.

Now, for the fueling to go leaner with colder denser air implies that the DME is infact not at all intelligent and is like that of a Bosch Motronic 1.1!
A denser cooler charge will actual require more fuel and if that did happen then the AFR will be maintained.... like we would hope.
An intelligent DME will not allow this unless the base calibration for fuel is too far out for the aim to reach as mentioned above.

It's all quite logical.

I am by the way not going to comment on if the AFR is lean or rich on any graphs. Who knows... could be down to placement of the probe. Could be a break in the pipe drawing in air? Who knows?

(opens packet of silk cut silver and begins to smoke)

100% Spot on sir. The days of Motronic are long gone. I actually have the Motronic 1.3 first adaptive Bosch ECU sitting behind me. It's an old school brick - particularly terrible when boost is introduced. It was fifty times harder to tune that DME for boost over something sophisticated like the MSS60 - this is a walk in the park!

And yes, if the fuel factor table ramp up is not set correctly on an S/C car, this can cause issues with inconsistent fueling. You're referring to the map at address 0x797xx I'm glad were on the same page.
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Last edited by Mike Benvo; 10-03-2012 at 05:50 PM.