Friday, March 28, 2014

Tuning: Re-tuning with a Temporary MAP Sensor - Part 2

So after rewiring the AEM FIC and adjusted the maps, it's time to test the map.

Start up is fine, fuel trims seem to be normal. Conservatively, I added a bit more fuel in the transition and in the boost sections of the fuel map.

Now let's add some gas and see what she does!

Driving under vacuum shows nothing notable, which is perfect. Fuel trims again, remain as per normal.

I start to push the accelerator a little more deeper. The boost gauge breaks the 0 psi barrier and... Whoa! The Air/Fuel Ratio Gauge pegged rich! Now I can either adjust the Fuel cells with new values or adjust the Y-axis scale. I worked so hard to get the original tune with the on-board MAP sensor so I'll try to adjust the Y-axis scale.

Accelerating once more I identified the break point to which the first psi was seen and I found that it was already quite high in the fueling map. So I brought down the Y-axis by changing the values to a lower number. After a few runs of accelerating, checking AFR and adjusting the Y-axis I was able to (sort of) remap the fuel map to the new voltage values.

In the least, I have regained fueling control and can safely enter boost. So let's do a full WOT run.

I logged the run and from the log data I checked to see the voltage of 'MAF IN' at max boost. I expected to see the voltage at 1.56V (as I estimated previously) but I found that the max boost 'MAF IN' voltage was actually 1.655V. Time to re-adjust the Y-axis once more.

After a few iterations of driving and adjusting, I was able to get a somewhat stable tune. Wasn't perfect as I did feel a lot of hesitation during initial acceleration. Perhaps the boost sender didn't have a fast enough response time.

Well, I now have a temporary solution which should hold until I work out what I'll do with an AEM FIC with a dead MAP sensor.

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