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-   -   Temperature compensation? (https://www.miataturbo.net/megasquirt-18/temperature-compensation-12560/)

paul 09-13-2007 10:48 AM

Temperature compensation?
 
Is there a trim setting for temperature compensation in the MS? Here is my problem. I tune the car while it's 80 degrees out and it runs great achieving all my AFR targets. Then I drive the car when it's 70 degrees and it's rich all over the board. So I tune it at 70 degrees and it's rich when it drops to 60. 53 degrees last night was interesting.

Running the 94/95PNP with the IAT sensor, no MAF. The IAT sensor is mounted in the intake charge piping after the intercooler, about 8" from the throttlebody.


Also, should the various settings be on Speed Density not Alpha-N/Hybrid Alpha-N? From what I took from the manual I thought Alpha-N or Hybrid would be correct but when I chose it the program loaded with warnings of lots of errors so I set things back to Speed Density. When I flashed my MS a few weeks ago to remove the MAF various files were missing for the flashing to occur so I just copied said files from the "with MAF" folder.

Braineack 09-13-2007 10:54 AM

use clt related air-density, go under advanced and change clt to ait.

paul 09-13-2007 10:59 AM

Advanced > Coolant related ari-density > settings > coolant corrected air density ?

then change "Normal Correction" to "Corrected"
and Correction Based on to "IAT Corrected" ?

richyvrlimited 09-13-2007 11:02 AM


Originally Posted by paul (Post 150379)
Advanced > Coolant related ari-density > settings > coolant corrected air density ?

then change "Normal Correction" to "Corrected"
and Correction Based on to "IAT Corrected" ?

exactly, tho I don't get the issue you're having, you'll have to set the range of correction to span the whole revrange.

I use IAT based compensation between 500 - 1500rpm to cure a lean condition on hotstarts as the standard compensation is faaaaarr too agressive.

I initially nicked someone elses settings which worked okay, but I've since spent some time tuning them further, and I can honestly say I've never been happier with the way the car runs now :)

paul 09-13-2007 11:29 AM

I understand that air temp decreases it becomes more dense. so the colder the air is the more fuel you need to maintain the same AFR, correct? It seems that it's adding too much fuel as the air temp drops so when if I tune my car when it's warmer it runs richer when it's cooler.

So after changing it to IAT corrected should I be experimenting with the "Offset(%)" settings for each temp input?

richyvrlimited 09-13-2007 12:05 PM


Originally Posted by paul (Post 150385)
So after changing it to IAT corrected should I be experimenting with the "Offset(%)" settings for each temp input?

both, it's intorpolated into a curve tho, so use break points for the temp, and go from there.

Splitime 09-13-2007 12:45 PM

Its wierd that the car richened up when it got colder... typically it leans out...

Braineack 09-13-2007 12:47 PM

ive experience the same, leaner at high temps....

richyvrlimited 09-14-2007 04:05 AM


Originally Posted by Splitime (Post 150420)
Its wierd that the car richened up when it got colder... typically it leans out...

It happens because the default temp compensation curve is too agressive.

I can understand why though as it's far safer to be to rich than too lean :)


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