MalibuJack

iTrader: (5)

I mentioned this in passing.. But you guys need to check

1) Barometric Pressure Compensation Table
2) Air Temperature Compensation Table

As mentioned earlier, Air Density / Air Mass is calculated by the ECU, and my guess is one of those two tables needs tweaking now that the engine's VE has been altered.

C6C6CH3vo

iTrader: (9)

Were on it Boss

OK, I did a log at lunch air temp log is 60F - 68F.

A:F 11.7 from 5000rpm to 6500rpm

50 45u
77 41u
82 34u

I changed my air temp comp to the following:

50 41u
77 41u
82 41u

At same temps (60F - 68F) A:F dropped to 11.4 to where I like 'em

I assume tomarrow at 80F instead of 11.1, I'll perhaps be at 11.3, well see


I will tailor to climate later more sensibly later

MalibuJack

iTrader: (5)

Good stuff.. Yet one more mystery almost solved..

Jorge T

iTrader: (18)

Can it be that The lower the air temp the less chance of knock, the leaner the engine can run and that is why Mitsu set the temp comp like it is?

C6C6CH3vo

iTrader: (9)

Probably, but perhaps also used in conjunction with a change in altitude

It sure would be nice to have the chief engineer's logbook (in english) at Mitsu written 4 years ago

Here is how not only the effects of temp have on air volume but also how temp comp may play an indirect role by leaning at lower temps.

A WOT log this afternoon at higher temps with 41units will only confirm this

jfitzpat

The point was that when VE changes the calculation can become incorrect.

C6C6CH3vo: You mention a change in altitude.

This is a good point. It isn't the general density of free air that matters for combustion, but the partial pressure of O2. In barometric pressure, 1000' of altitude change equates to about 1" of pressure up to almost the troposphere, but O2 follows a different, less linear curve.

-jjf

MalibuJack

iTrader: (5)

FWIW, the charts you have done are in Fahrenheit, and the Tables are in Celcius.. Just make sure the alterations are done in the right place..

32 degrees Fahrenheit is 0 Celcius..

C6C6CH3vo

iTrader: (9)

I'm almost 78% certain the chart is mislabled as "celcius" and that the temp value corresponds to MAF temp in F. Also I am seeing real changes in WB from input in those areas - for now I will have to trust that it was just an overlooked mistake

-32 degrees Centigrate would be -57 degrees F an 84 degrees C would be 183F. I don't think intake temps reach those extreems.

Another thing they did was use the word Celcius for C, C is Centigrate and always has been. Celcius was an opium fiend and his name took credit for the unit of measure by mistake and still does today.


Anyhow, air temps reached 90 degrees today and my A:F has changed very little compared to last nights 60F log. However, there was nowhere near the power, but at least a little more than if A:F dipped into the 10's

Rob W.

iTrader: (8)

I appreciate the effort you're putting into this, but I do have to point out that -32C is definitely not equal to -57F!

-32C == -25.6F

C6C6CH3vo

iTrader: (9)

Ooops Sorry

Dyslexia. I'm alreight until negative values, but that stuff about Celcius is mostly true, I can assure.

(C*9/5)+32 = F
(F*5/9)-32 = C

My question now is wether or not that table supposed to be C (Centegrate) of F. If C then what in the world is it measuring?

Rob W.

iTrader: (8)

Personally, I'm betting it is indeed Celsius/Centigrade, not F. Of course the upper two values are very high, but if they were in F, they'd not really be high enough IMO. Also, keep in mind that this isn't ambient temp the ECU is measuring, it's intake air temp. It is very feasible (and likely) for the underhood intake temp to get into the mid 100's (F).

Also, I work at a Japanese company. Trust me, they don't know F. They don't work in F. I hate to stereotype, but there's no way a Japanese-made ECU has anything F in it.

I'm excited to see that you saw a difference by tweaking the values. I'd like my AFR to stay more stable with our wide-ranging MI weather. (and I'm very jealous about your 85F comments as I sit here in northern Ontario doing cold-weather vehicle testing!!)

klatinn

Just a little correction:

(F - 32) * 5/9 = C

I'm doing this everyday mentally because I am STILL not used to use somebodies armpit as temperature reference
According to legend, when Mr. Farenheit invented his thermometer, it was a cold winter. He put it outside and read it early in the morning. He thought it cannot possibly get colder than that. So he marked it there with 0. He then went inside, looking for a higher temperature reference. From working outside he developed a slight fever. He stuck the thermometer under his armpit to see if it reacted. It did nicely so he marked that temperature as 100. That's how the Farenheit scale got invented.

Regards,
Klaus

EVOllie

iTrader: (10)

There is a lot of post in this thread for something that is normal.

All you guys sound like scientist.

Rob W.

iTrader: (8)

Just because it's normal doesn't mean that it can't be improved upon.

EVOllie

iTrader: (10)

yea....u adjust your tune for temp, boost and oct.

the question was "does anyone else have a change in A/F with change in temp"

the answer is yes...its normal.