MicroSquirt.com read only forum (Jan.15,2018)

having read through the manual, it seems that tps input is only used for accel/decel fuelling?

On my car, in a high gear i can apply small amounts of throttle and see a bar of boost. I can also floor thr throttle, with the car pulling much harder, and not have any increase in MAP if the boost is limited to a bar.

The point i am making, is how would MS know to give less fuel on part throttle for the same boost, as on full throttle?

Rick.

see http://www.msefi.com/viewtopic.php?t=16087&highlight=

AW

Thanks for the link, interesting reading.

However, that seems to be dealing in transient fuelling. What i'm talking about isn't really transient - the throttle position essentially effects the VE of the engine, for a good few seconds at a time if not more - longer if the turbo is smaller and spools up quickly.

I would have thought, u could apply a throttle multiplier to the VE map to get round this issue.

Are you using MS yet? It works the way it does because as the MAP rises, MS adds fuel to compensate, regardless of throttle. I'm running a turbo car well over the factory output with stock driveability. The latest code in -extra is the best yet with RPM Accel.

MSI v2.2 -extra029i 2.25MT

Hi there.

No, i haven't yet, but i defo will be. I am very demmanding of my setup, so am just doing as much reserach as possible.

The car runs boost of upto 36psi, but with vey nice off boost manners. I have no doubt that i will be able to acheive good driveability with MS - i have done in past with far less capable setups.

The question is more about fundamentals - ie it seems that a TPS multiplier would be a very good idea?

Rick

MegaSquirt responds to changes in Manifold Absolute Pressure in order to calculate fueling requirements. As you stated above, there are times when an increase in throttle position makes no change in manifold pressure. In these cases, of course you still want more fuel, and that's where AE (acceleration enrichment) comes into play.

Acceleration enrichment adds fuel based on throttle travel. Take a good long look at the tuning section of the megamanual.. it will all fall into place.

-Brian

This is why I intend to use boost table switching, so when im pootling around or doing motorway journeys I can stick to actuator pressure and not waste fuel/turbo wear.

78Spit1500Fed wrote:MegaSquirt responds to changes in Manifold Absolute Pressure in order to calculate fueling requirements. As you stated above, there are times when an increase in throttle position makes no change in manifold pressure. In these cases, of course you still want more fuel, and that's where AE (acceleration enrichment) comes into play.

Acceleration enrichment adds fuel based on throttle travel. Take a good long look at the tuning section of the megamanual.. it will all fall into place.

-Brian

This means that you rely on TPSdot, which it seems is less capable than MAPdot?

RickRST,

MegaSquirt-II (and MS-I with MSnS-E code, I believe) has both MAPdot and TPSdot code, and you can choose either, or a mix of the two.

However, your assertion that "the throttle position essentially effects the VE of the engine, for a good few seconds at a time if not more - longer if the turbo is smaller and spools up quickly" is not right, at least not the way MegaSquirt defines VE.

The cylinders have no idea about the position of the throttle. Throttle position is reflected in the manifold pressure, of course, which does affect the VE, and which MegaSquirt accounts for.

Perhaps you are talking about the operating point of the turbo in the compressor map moving, but as long as you are measuring the MAP near the cylinders and the IAT in a similar location, you should be okay.

Lance.

RickRST wrote:having read through the manual, it seems that tps input is only used for accel/decel fuelling?

On my car, in a high gear i can apply small amounts of throttle and see a bar of boost. I can also floor thr throttle, with the car pulling much harder, and not have any increase in MAP if the boost is limited to a bar.

The point i am making, is how would MS know to give less fuel on part throttle for the same boost, as on full throttle?

Rick.

Hi,
perhaps you can use "Boost Controll" in MSN-Extra to get this behaviour
http://megasquirt.sourceforge.net/extra/boost.html