Acceleration compensation

["Graydon D. Stuckey" <graydon@apollo.kettering.edu>]

On Wed, 17 Jun 1998 QSHIPQ@aol.com wrote:

> "When the throttle valve opens suddenly, the air-fuel mixture responds by
> leaning out briefly.  This is due to the fuels restricted vaporization
> potential at higher manifold vacuum levels (increased tendency to form fuel
> layers on intake tract walls)  To obtain good transition response, the mixture
> must be enriched by an amount which varies according to engine temperature.
> This enrichment privides good acceleration response."

This is why my (and most other) efi system has an acceleration 
compensation routine that is calibratable from my laptop.   I can adjust 
how much additional fuel the engine gets under any combination of rpm and 
load.   Its also temp dependent within the ECU's own calculations.

That's also why 4-barrels have an accelerator pump that shoots extra fuel 
into the carb when you floor it.

> Hmmm, if I insert an EGT temp sensor to do the "vary according to engine temp"
> would I be accomplishing a better rich mixture and transition response?

I doubt that the EGT sensor could react fast enough.  An IR egt sensor or 
a laser EGT sensor might do the trick though.

> Certainly better than how audi does it now?  Would a better O2 do the same
> thing?  

Even a current O2 sensor does just fine at detecting this transient 
response.  Ford's EEC-IV has the capability of detecting each individual 
puff of exhaust and calculating which cylinder it originated from with 
current O2 sensors, one in each bank.  Those O2 sensors react _very_ fast.

Later,
Graydon D. Stuckey

"There's alot more to Jazz than just wrong notes"