As the power levels rise and turbos and inductions become larger it becomes more difficult to control fueling at low loads via a MAF. One option is a totally MAP based ECU although this can also give driveability issues and is subject to AFR offsets from changing exhaust gas temperatures.(unless you have a very expensive ECU which monitors this)

There are a few convertors available that will convert MAPxRPM into a basic MAF signal although there can be low throttle enrichment issues here.

It has been discussed in a previous thread that a combination system may be the answer.

Andrew Carr can make the interface microcontroller and John Banks is good with writing the code for it.
All we need to do is decide exactly what we want and when !

My first stab at a configuration would be -

Low load steady throttle fueling from TPS, perhaps then a combination of MAF spike and TPS based enrichment during increasing TPS, then map and TPS during decreasing TPS, finally MAF only at WOT on boost.

Andy

 

Interpolated 3D map (I have the code for an 8*8 with editing ) of DeltaTPS vs TPS with a lookup of proportion of input from TPS and the rest from MAF?

You need smooth transitions everywhere because no two load measurement methods will ever produce anything other than a step change when you switch between them.

 

I would dispense with the MAP altogether initially.

I have no issues above about 2000rpm, less at WOT.

I think you need to try initially with something that is 100% TPS from 0 to 1500rpm, the feathering to 100% maf by about 2500rpm, with a further increase in the MAF weighting dependant on MAP. But not actually use the MAP to calculate load.

Paul

 

That would be a lot simpler and quicker to try. Need a third ADC input for the MAF signal, but that is easy enough. We already of course have TPS, RPM, MAP inputs, and MAF output.

 

The link plus can actually be set to use the TPS for all load zones up to atmospheric, them MAP beyond that.

 

How would 'TPS only' cope with the ISCV, anti stall blips, air con load and cold start ? I think it would need some MAP input to identify this ?

Andy

 

Suppose so, but then not using MAF you'd have that dull off idle transition we had with MAP/TPS?

How about damping or filtering the MAF signal in certain situations?

How about designing a nice airflow pattern into your intake for the MAF to read with baffles to stop reverse flow through the MAF?

 

hmm, forgot about the ISCV. Turn off the whole system under idle conditions.

Paul

 

Baffled maf will help, I have plans for that
There's an issue as you come back to idle though Paul as the flow is tumbling around in the inducer area.

Andy