MAP or TPS load scale

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Joined: Wed Sep 02, 2009 10:28 am
Location: Tasmania

MAP or TPS load scale

Postby Robbks » Thu Nov 04, 2010 11:31 am

I've been looking over some tuned interceptor maps lately for Turbo Subaru engines.

both tuners are well respected within the Subaru community but i struck one glaring difference.
Both cars were MY99 GT Foresters with similar modifications.
One tuner used MAP for the Load sites within the interceptor maps and the other used TPS.
Both cars stock ECU takes MAF readings as their primary load input (intercepted and modified by the interceptor)

any reason to use one over the other?
better control of the tune/ economy/ drivability with one or the other.

I use MAP based load sites on my own Subaru with interceptor installed, but wondering if TPS % may be a better option?

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Joined: Thu Sep 10, 2009 9:43 am

Re: MAP or TPS load scale

Postby vosadrian » Fri Nov 05, 2010 12:50 pm

TPS is not recommended on a turbo car. Depending on the boost control setup, 100% throttle could mean 10psi one day and 15psi the next. Therefore you apply the same correction at different boosts.

Map is nice because it get around above problem, but to tune is very easy as a certain boost level corresponds with a certain column in the maps.

You can also tun on maf, but more difficult to tune as a certain boost level will up diagnally in the maps.

Maps is th best compromise of ease of tuning and reacting to changes in boost.

-- Adrian

Posts: 96
Joined: Wed Sep 02, 2009 10:28 am
Location: Tasmania

Re: MAP or TPS load scale

Postby Robbks » Fri Nov 05, 2010 1:04 pm

Thanks again Adrian,
As above was your previous advice to me and as such i have chosen to use MAP load sites for my own purposes (being sequential twin-turbo also throws in a another variable given there are two very different airflows for each pressure... :shock: :shock: )

I just found it interesting that both tuners used very different approaches to achieve the same result on basically the same cars/ modifications

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Re: MAP or TPS load scale

Postby Blackjack » Thu Jun 14, 2018 7:31 pm

VE is a misleading term when used in mapping. The fuel quantity injected and resultant lambda reading are significantly affected by many factors beyond the amount of cylinder filling (volumetric efficiency represents a percentage of the swept cylinder volume, for those that don't know the lingo). Not getting at you Peter, I just hate the use of the term!
I'm not the only mapper in the world obviously and don't doubt there are people more capable than I am, but I personally find, if the TPS is well mounted and precise, it works best on its own as load reference for both fuel and ignition on an ITB N/A engine. I've been all around the houses using it separately or overlaying pressure correction on TPS load and in each case it caused more problems than it solved. The theory is sound of course and on standard-ish engines, where the fuel and ignition requirements are pretty predictable and linear, it's less of an issue, but with tuned engines, particularly N/A race engines (which is what I specialise in mapping), speed of response requires a certain amount of anticipation and a high degree of repeatability in the settings, to get what you need in transient conditions and MAP plays absolute f*** with that; ditto live closed loop lambda correction.

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Location: NY

Re: MAP or TPS load scale

Postby Nanosa » Thu Jul 12, 2018 9:26 pm

On my car there was such a problem 1.5 years ago. I used the same technique and it worked out.

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