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Webinar #317. ITB Tuning.

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Ask questions about webinar lessons here. To see the Previous Webinars for a complete list of archives tuning webinars. 

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Fuel trimming via MAP with a TPS load axis. Is this in addition to BARO comp?

Why would this be necessary at all since, using Andre's example of transitioning from level to a slight incline, the increased load under a constant throttle opening would cause the engine speed to decrease therefore operating in a different cell in the fuel table? Albeit very slight, but 'intercell' interpolation would still come into play.

I was also a bit puzzled by that, too, for the same reasoning. There may, indeed, be very good reasons for it, and it may work perfectly well - as Andre explained - but the benefits (if real) seem small, and the chance of the average person compounding setup problems high.

Barometric correction, from a pressure sensor in the airbox or plenum, would be a good idea to counter changes in elevation, air pressure changes from weather, possible 'ram' affect from ducted air feed, dirty air filters (might be possible to have a warning for excessively low pressure in the manifold/plenum, especially if there's an option to compare to ambient), etc.

No one else wants to chime in?

Just finished the Webinar so now I can pipe in.

I am running a set of Borla ITB's on a Ford Big Block. Performance Electronics ECU which incorporates both the MAP sensor and the additional Baro sensor. I chose to add the Baro sensor since it gives you real time adjustments to compensate for altitude changes. I've done a fair amount of mountain cruising and if you use just the single MAP sensor, it sets the Baro reading at engine start and maintains it til the next key start. I felt it would just make for a better compensated engine having each sensor doing its job rather than sampling for a Baro pressure then running with this for the next hour or 6,000 ft elevation change.

Not sure if this adds or confuses the question, much of this is way above my paygrade.

Thanks for your input Paul. My ecu (Motec gold box), does continuous BARO compensation. Does your setup use MAP or TPS for the load axis on the fuel and ignition tables?


I run with an Alpha-N setup on all tables. TPS is the load indicator. My ECU allows MAP compensation which then fine-tunes the setup.

I've had two of these setups. The first one, I ran to the top of Pikes Peak here in the States. 8,000ft elevation change and the car ran like a champ. Others were struggling with an overly rich system and mine ran as if it were at sea level.

Not sure of your geography but if you're doing any runs with a great elevation change, I recommend the additional Baro Sensor.


OK, so let's assume for the moment that drivability improvements can be realised by having some MAP compensation when using TPS as the load axis independant of BARO compensation.

What methodology would be used to calibrate this?

The Baro is pretty simple, a basic 1 to 1 ratio is what I was told. (pressure drops 10%, drop the fuel 10%)

For the MAP sensor, you're going to need a dyno. Andre speaks to how engine load can vary while the TPS stays relatively constant in the webinar. If it is a MAJOR (coarse) adjustment, you might notice it while driving but the fine tuning, you'll only find it on the Dyno. Or at least, this is how I understand it.

OK, so digging up an old thread here. Using both TPS and MAP for engine load reference. The main fuel table would be TPS based with MAP as a fourth axis set to 'double pressure/double fuel'?


Yes, that’s exactly how you do it!

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