hector

I have a DIYPNP and ran across this thread and decided to check my settings. Im usind TS 1.006 MSextra 3.2.1 code. It has a mat non linear correction table and all the entries were at zero so I figured it was doing nothing. I then went and changed the mat correction value to 50% as recomended and my AFR readings all went rich. So I guess the correction value is in effect regardless of any values in the non linear correction table?

As an aside, my mat went down 7 degrees at highway speeds with the headlights up. I have a cone filter at the end of the stock MAF location with an aluminum heat shield. Dont know if this is news to anyone but it cant hurt to share.

aaronc7

iTrader: (8)

I found changing the correction value wasn't a good idea for MAT corrections when the car was actually running. On cold days it went lean, switched it back to 100 value and all was good. Sadly we have no way to taper off the non-linear MAT correction table with RPM like MS1 can.....that would solve our issues I think for hot starts.

Some of the latest firmware changes allows you to disable MAT corrections during ASE among other tweaks, which should help, but I haven't got to test them out yet.

hector

Im not having an issue with hot restart actually. I just started messing with the MS recently and have been doing lots of reading and figured why not try a suggestion. Honestly, it made a big difference that was not just noticeable in the AFR gauge but in AE as well. I havent gone back to see what the AFR is on cold start up so I cant say how much of a change it will make there. Of course cold start up is a relative term at this time of year around here since 80* is close to an overnight low. Also, dont know if my MAF's MAT sensor is properly calibrated. I used DIY autotunes resistance values so I would say theyd be as goos as any.

gslender

iTrader: (1)

I added the "disable MAT corrections during ASE" in the MS2 mod that has this functionality. I guess adding a "non-linear MAT correction table with RPM" would be doable and so if you can ellaborate further on how this would work, I'll take a look at it.

G

Braineack

iTrader: (62)

You gotta set that value and forget it. If you change the correction value to 50%, you're cutting the ideal gas law code in half. So whatever is currently in your MAT corrections table essentially doubles.

I would like to taper off MAT corrections both by RPM and maybe by Boost*, myself. But I'd also like to keep the MAT correciton value at 50% as I still think it's very aggressive -- even at 50%.

But what you really need to tune the MAT corrections Curve by negating any Gair addition.

for example, with a correction value of 50%, this is the table I use:



This completely negates the ideal gas law AIT enrichments and keeps Gair at 100% throughout the temperature range. This way, since I can't decay out the enrichments, it hot starts arent an issue and neither is my AFRs in boost. I guess honestly it's the best way to go about it.

*boost decay is probably not needed if the Gair stays at 100%, I had issues on the dyno once where my MAT corrections were keeping Gair above 100% and I was dumping in too much fuel in boost. I don't seem to have this issue anymore.


I'm the one that convinces James to add that feature. The problem is ASE only lasts for maybe 10 seconds on my car? And that's not enough time to get the temps back down at idle. My AIT sensor is located just aft of the IC...however my BOV, which leaks at idle, is located just pre-TB. That's my main source of air at idle, so air does not flow over-top of the ait sensor at idle...so when it does get a bit heated up, I have to wait until I'm actually driving before it drops back down.

Even in the current position, I can see a good 20-30°F delta, on a hot day, within 5-10mins of sitting with the engine off.

But one thing that's a bit shocking is, last summer I was doing a good deal of testing, using a second AIT sensor in various locations under the hood, is that the AITs are pretty much whatever my "heatsoaked" sensor was saying. I had an input switch a relay to my second AIT sensor at any rpm below 1200RPM, it was clever, and I had strapped a small 1" CPU fan to the element to ensure airflow. I tried it directly behind hte rad, under the headlight, in the cowl, and under the driver fender...all the temps would read within 10°F of the sensor in my IC pipes.

This lead me to belief that the ideal gas law code, while technically/logical/mathematically LAW, is flawed when it comes to how it's implemented in the MS code...because the air temps rising from 70°F to 85°F do NOT and should NOT require such an agressive amount of fuel (~6%) to be pulled as the code wants you to pull.

But like I said, I just use the above table and really have no issues anymore, at least I have bigger fish to fry and I'm tired of bring it up with Ken and James.

aaronc7

iTrader: (8)

Issue I had with the 50 percent correction value was.... tuned WOT for good AFRs on a 70 degree day (ish), then a few weeks later it was down in the 40s, and it ran lean consistently. Wasn't adding enough fuel. I set value back to 100 and it was pretty good, retuned and haven't observed any issues with temp fluctuations while in *driving conditions*. Idle is a different story. I almost wonder if IAT reads high in heatsoaked conditions due to small amount of air flow inside of pipe and lots of heat inside the metals all around the sensor, and that hot metal is having a larger impact on the sensor than it should. Anyone run IAT with the FM/all silicone piping? I'd be interested to see it performed in that.

I don't recall seeing anything crazy like 6 percent correction for a 15 degree F change in temps, but it's been awhile since I've drove the car.

I got to see the "Non linear MAT table correction decay with rpm" in action on a Reverant unit a week ago and it seemed to work great, never had any hot start issues while doing a bunch of idle troubleshooting...sitting inside a garage with hood open (it was getting hot). He uses 100 correction value as well.

Agreed that the ASE thing is a good step but really doesn't solve the issues that I've seen. My idle didn't "get better" until I started moving/increased load/rpm on the engine. and I dont have a leaky bov or anything at idle. My AIT/IAT whatever is on coldside IC piping, in front of radiator (over the radiator piping).

aaronc7

iTrader: (8)

PS I PMed GSlender about implementing the RPM based decay, referencing some other threads on here and on MSextra.com- I'll be stoked if it actually makes it into his latest firmware. I've considered going to Reverant DIYPNP just to get the RPM based decay stuff...

Reverant

iTrader: (10)

Yup, I've never had a problem or complaints with my solution. AFRs stay the same in boost/vacuum whether it is winter or summer, and heatsoaking is no longer an issue on restarts.

Braineack

iTrader: (62)

sounds like you didnt have things tuned correctly. like i said, if you left the MAT corrections table untouched, but changed the MAT value it 50%, you'd have issues like the above.

probably a little better, but did oyu even read my schpeal about the dual AIT sensors?

Then you've never looked at Gair (the air temp based enrichments)

using a correction value of 100% is fine, just double the MAT corrections table I posted above. Get it?

I still worry about the ideal gas law code pulling too much fuel in boost with just this strategy implemented. I'd like to hear Reverant's take on it, but let's assume you have it decay out at 3000RPM, and you get into boost on a 90°F and get your intake temps up to 150°F. Once you decay off the corrections, the ideal gas law code will pull fuel an dyou'll be lean in boost...exactly where you DONT want to be lean.


I see the same thing. One that that helps extremely well is Seq. fueling...since you can still idle smooth at like 15-16:1

Braineack

iTrader: (62)

can you comment on my post about getting into boost with high AIT temps?

gslender

iTrader: (1)

Braineack, have you tried setting the MAT value to lower than 50% ?

It is just restricted by the ini and the ecu code will take lower values down to zero% effectively turning the ideal gas law off?

G

aaronc7

iTrader: (8)

My problem with the 50 percent correction value was it was not aggressive enough when temps dropped and Gair was going positive..and end result AFRs were lean. If I recall @50 percent, Gair was 101 and @100 percent, Gair was 103. The 103 value put my AFRs back where they should have been more or less. Forcing Gair to always be 100 thru the non-linear table would have made it be even leaner, right? I have not personally had issues on the high AIT side of things and 100 correction value being too aggressive and making things run lean. Maybe I have just not had high enough AITs...hard to say. This is all in boost/cruise conditions.

Bottom line I haven't seen issues with the 100 percent correction value for boost and cruise conditions...but that is just my experience, I'm not questioning yours. I also forced Gair to be a constant 100 like you showed above, but I saw it go lean/rich with temp changes, depending on if it was hotter/colder...as in I needed those Gair corrections for AFRs to be consistent.

My only issue is it going mega lean on hot starts in the Florida summer. Is it due to inaccurate MAT readings (your testing would indicate this is not the case), or due to code being overly aggressive.... IDK, but I think the RPM based decay would solve my issues (how Reverant approached it).

GSlender- what he's doing with the non-linear table vs being able to change correction value *should* be the exact same thing in the end.. which for ME....made hot starts not an issue, but threw off AFRs for everything outside of idle when temp corrections were needed (hot vs cold day). I basically would like a way to alter Gair at idle/below XYZ RPM independant of cruise/WOT.

Braineack

iTrader: (62)

I still don't think you quite understand the correlation between the MAT Correction Value and the MAT Correction Table.

What you are suggesting above it that your VE table was tuned incorrectly as it acutally needs MAT corrections in order to get the correct AFR. This is bad and will always lead to trouble when the temperature changes. You should tune your VE table when no enrichments are active, then you can fine tune the enrichment based on temperature condition and NOT the fuel table.

aaronc7

iTrader: (8)

For clarification... I had tuned the VE table weeks prior in moderate temps of 60-70 degrees, MAT corr value 50. Minimal MAT corrections applied, probably 1 percent at most in cruise at those conditions? I don't think the VE table was the issue. Anyways, then temps dropped down into 30-40s and that's when I ran into the issues and had to increase the Gair corrections for the now lower temps I was seeing...it was not being aggressive enough. Never touched the VE table.

Could MAT based timing retard be playing into boost/high MAT fueling as well too? Or does the code somehow adjust for any timing it's pulling as a result of high MATs.

Either way I don't want to get sidetracked on this, I just would like to see the RPM based MAT correction decay as discussed above in MS2.

Braineack

iTrader: (62)

but what was Gair when the temps dropped?

I run the same VE table with 0% ait corrections from JAN-DEC...

if the VE table didnt change, but the AFRs gotta shitty when cold, it was due to a poorly tuned mat corrections table. Changing the value back to 100% probably just correlated better to what you had/have plugged into your corrections table...but you could have the opposite problem when the intake temps get higher come summer.

sixshooter

iTrader: (12)

THIS sounds like the "high AIT - lean in boost" problem I am experiencing. Why don't I just set the enrichment to decay at 7200rpm and never need to worry about going lean and blowing up the engine in boost? 95 degree track days with 140 degree asphalt temps and then going into boost on top of it means lots of fuel being pulled when you need it most.

aaronc7

iTrader: (8)

IIRC around 101 Gair @50% MAT value, and then it went up to 103-104 @100% MAT Value. Might have been 103 to 106, but either way, after the switch, AFRs were back to what they were, pre 30-40 degree temp drop.

This is all with zeroed out non-linear MAT table. I had messed around with that in the past, but it wasn't a factor in all of this testing.

Very interesting that you run same VE table year around with no air temp corrections to fueling... that has just not been my (limited) experience at all for when outside air temp changes significantly.

Wish I had a running car at the moment to mess around with this stuff, but I'm stuck just trying to remember back several months or more.


You have MS1? If so then yeah, you should be able to do that so that table is being used all the time to get your AFRs where you want consistently in boost, at whatever temp.

gslender

iTrader: (1)

I think I've found a bug in the air correction calculations that might explain why it isn't working when it should.... stay tuned!!

aaronc7

iTrader: (8)

Staying tuned

aaronc7

iTrader: (8)

http://msextra.com/forums/viewtopic.php?f=91&t=45364