MAT table starting place?

6040solder · Post by **6040solder** » Tue Mar 04, 2008 10:59 am

If you are using less fuel than ms thinks you are by a fixed amount, that would exhibit this behaviour. i.e. opening time set shorter than it really is. That would be more obvious at lower pulsewidths, i.e. with more percentage error. There may be other config issues that could cause that too I guess, but I can't think of any right now, and typing this post with one hand is going rather slowly :-)

hassmaschine · Post by **hassmaschine** » Tue Mar 04, 2008 11:30 am

yeah, I don't have a scope so I'm going off the specs I've seen and playing around between simultaneous and alternating - the specs called for 1.14ms opening time, and I found it to be about the same with this method.

I think it's pretty close, but I have another problem in that my idle PW is close to the opening time - so my idle is really sensitive to PW changes (I'm using rather large injectors on an N/A motor). it probably magnifies the issue some but I can still wish for negative correction factors. :p

ol boy · Post by **ol boy** » Tue Mar 04, 2008 1:13 pm

How much of a change are you guys talking about here? Fully warmed up when it 30*F outside your AF goes from 13.8 down to 13.3 and when it's 110*F it leans from normal 13.8 to 14.2? Sounds like simple math should give you some idea of how much VE change to make and recurve the MAT correction starting from 0*F(15%) and ending around 140*F(-10%). Once the MAT slope is close small changes in VE should dial it in.

Just an idea.. Later Ryan

hassmaschine · Post by **hassmaschine** » Tue Mar 04, 2008 2:32 pm

ol boy wrote:How much of a change are you guys talking about here? Fully warmed up when it 30*F outside your AF goes from 13.8 down to 13.3 and when it's 110*F it leans from normal 13.8 to 14.2? Sounds like simple math should give you some idea of how much VE change to make and recurve the MAT correction starting from 0*F(15%) and ending around 140*F(-10%). Once the MAT slope is close small changes in VE should dial it in.

Just an idea.. Later Ryan

at around 0c it will be ~13:1, at 30c it will be ~16:1 (with MAT correction set flat).

and -10% wont' work, you can't enter in negative values :p

md95 · Post by **md95** » Tue Mar 04, 2008 3:19 pm

I've never really used MAT correction for cold temps, although I could use it as well. I know MS1 Extra used 100% value as "no change", and for example, 110% would be 10% more fuel, and 90% would be 10% less fuel. How hard would it be to modify this for MS2 Extra? You would have more adjustability that way.

mops · Post by **mops** » Tue Mar 04, 2008 4:32 pm

yes, i have spend alot of time on that subject myself.

temp sensor placement is crucial.
those temp sensors behavior is far from ideal.

You want the sensor is with lowest thermal mass (read: small) inserted into the center of airflow, away from any walls/other things that can radiate heat to get any accurate reading, and how fast it updates is questionable... so you cannot really 100% believe your MAT sensor, rather use it as a 'rough guide', except in certain conditions (ie. long highway cruise will stabilize under bonnet temps and everything else and there, so after 15 minutes of steady cruise the actual reading is pretty accurate)
Ideally i would like to see 2 temp sensors, one would be MAT and other would be 'outside air temp sensor', therefore ecu can estimate how heatsoaked things are....

Ideal gas law is ideal gas law and you cant change the laws of physics. The problem here is accurately measuring the actual air temp. It is easier to measure in high flow conditions (eg. wot), than in slow moving city traffic where things are bound to get... out of bound...

[edited to correct spelling]

ol boy · Post by **ol boy** » Tue Mar 04, 2008 10:47 pm

and -10% wont' work, you can't enter in negative values :p

sure you can. I can in MT with the 20071020 beta. I had to double check when someone mentioned there wasn't any negitive values. The center line on the graph is 0 with negitive low and possitive on the high side. I had entered the values of 100, 115, 120% and the line was at the top of the graph. gave a temp range of 0*F to 160*F with a %change startig at 10 and ending at -10 which gave no % change at 80*F inthe middel of the lines slope.

AbeFM · Post by **AbeFM** » Wed Mar 05, 2008 12:01 am

I checked it while plugged in, and I could swear the values were all 100%, and I could go up and down.

Later, in doubt, I checked it on my desk, and the values were all zero. I thought I was imagining it, but with other people's comments, I'm not so sure.

(b21)

Philip Lochner · Post by **Philip Lochner** » Wed Mar 05, 2008 2:23 am

AbeFM wrote:I checked it while plugged in, and I could swear the values were all 100%, and I could go up and down.

Later, in doubt, I checked it on my desk, and the values were all zero. I thought I was imagining it, but with other people's comments, I'm not so sure.

(b21)

AbeFM

Let's start where we should have started. Which version of the Extra FW are you running?

You posted on the MS2/Extra development forum which implies that you are using an MS2, and running either the released fw or a beta version.

6040solder · Post by **6040solder** » Wed Mar 05, 2008 2:25 am

AbeFM wrote:I checked it while ........... I'm not so sure.

(b21)

;-)

hassmaschine · Post by **hassmaschine** » Wed Mar 05, 2008 9:25 am

AbeFM wrote:I checked it while plugged in, and I could swear the values were all 100%, and I could go up and down.

Later, in doubt, I checked it on my desk, and the values were all zero. I thought I was imagining it, but with other people's comments, I'm not so sure.

(b21)

must have been added recently - I haven't used any of the newer betas yet. if it's true, then cool

spyro · Post by **spyro** » Wed Mar 05, 2008 10:11 am

its all 0 by default on rc1 with a max of 120%

ol boy · Post by **ol boy** » Wed Mar 05, 2008 11:38 am

I'm confussed... When you have the settings set to '0' across the hole temp rang does that disable the IAT correction? Seems that with these settings there is a defualt code you can't see which provides some correction. What is that correction% per temp increase or decrease? There has to be some slope line to work with thats allready there..? I'd look in the code but I have no idea what I'd be looking for. Thanks, Ryan

AbeFM · Post by **AbeFM** » Wed Mar 05, 2008 11:41 am

I haven't checked the code, but from what I gather this is merely a fudge factor on top of what's there to make the motor run. I guess you could unplug your sensor and see how it goes - my guess is terribly, then you'd know.

I'm home sick and my laptop's at work, so no luck making progress on this today....