Using MAP/RPM injection without TPS
Turbo Mini Forums

Hi,

I'm going to start developping an MPi injection for my 998 A+. I'll modify a stage 1 intake manifold to install one injector per port (and possibly a third common injector later).

As the volume of the intake is small I wonder if I need a TPS for the accel enrichment, or if I could use the MAP first derivative for this purpose. With a small intake volume there should not be delay between the MAP and the intake flow, so MAP should reflect the actual throttle position.

Did someone tried this setup ?

The goal is to run injection while keeping the carb. This would allow me to easily test the firmware and to map the engine step-by-step.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

MAP is directly related to TPS, the rate of change is almost identical.

I run AE on a MAP based input.

Great !
What's AE ?

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

sprocket,
if you are on an incline and open the throttle at a given rate would the map not be very different dependant on if you were going up or down the incline?
Regards
Dave

Edited by danboy on 19th Nov, 2007.

AE is Acceleration Enrichment

No, MAP is directly related to TPS, its rate of change will be almost the same. The point at which MAP reaches 100% in relation to TPS will differ with rpm, so, say at 2000rpm, TPS of 50%, MAP could be 100%, at 4500rpm and a TPS of 50%, MAP could be 50%, rate of change is the same. Where AE is concerned, its the rate of change that is of interest.

Thanks sprocket, so my guess was right.
I understand the throttle function, have been reading Heywood many times :) .

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm