Information on IAT Heatsoak and shitty/lean/EBC fail when hot
 

As the title states, I'm looking for some info about stuff I keep reading about but can't find with the search button.


When my car gets hot in temps at and above 75* it starts to idle like a mother fucker, sometimes it will fight between where it should be...13.9-14.5 and 16.9+ Other times it just wont idle worth a damn and the AEM can even read it is lean. I had another board member with MS said that this can be caused my IAT heatsoak...wondering why...and wtf can I do about it.

Also.

Went driving the other day, it started doing this along with a weird ignition miss. (FANS would not come on either...ftl) and boost control would not work worth a shit either...intake temps weren't stupid high, ambient temp was around 80, intake temps were around 130 on hard runs (or so).



Is this IAT related, or is this something about my car not being tuned/run in hotter weather before? Highest it had seen prior to this is about 65 degrees.


Can you guys point me in the right direction with this?

Do you have IAT correction enabled?

I don't know?

Go to megatune. Go to Advanced. Then Coolant-Related Air Density. Go to settings and then Coolant-Related Air Density. Change Air density correction to Corrected. Change correction based on to IAT Corrected. Set the bins.

hey sam, come get your valve cover!

I think i have some similar issues, i've got another thread going which i think has finally been resolved to this point.

What are people running for their correction #s? Lower and upper rpm range? Mine's set to 105% at 50degrees to 155 at like 100 or something like that, and the rpms are 2000 and 3000...

Seems a little weird no?? I would imagine you want correction throughout the rpm range, and my temp range seems short too, as i hate 120+ iat and it wasn't even 90 out today.

I have 100% from 20 - 80 degrees and then it slowly gets to 150% from 90 - 130 degrees.

The correction is done between 900 and 1500 rpm.

interesting.. so let me ask, why so low on the RPMs? Wouldn't you want to correct throughout the full range?

Thanks sam. I'll check this in the AM.

because EGO takes care of it.

or you could move the AIT sensor somewhere where it doesn't heatsoak.

Don't forget you need to edit the ini to also read MAT, if you don't change the ini, not only does the guage show incorrectly on the dialogue box, it also doesn't correct properly.

Searce for [CurveEditor] and change all CLT stuff to MAT.

I pissed around with MAT correction for bastard ages before I realised this, now it finally works!

Where would you suggest...it is right before the throttle body...not a lot of room here.

I think i'm in the same boat as the OP...

I played around with the Advanced -> Coolant correction..

I know it's "supposed to be" set to IAT correction, but like the OP, my car was super high AFRs with that.. I tried playing aroudn with the offset%, didn't make a difference... If i set it to CLT correction then it was a lot better, AFRs came down a lot.

I assume there's a benefit to using IAT not CLT, but i'm not seeing it right now !

-Tomaj

might as well just turn them off completely then. CLT temps mean jack shit when your sensor is reporting +120*F but its only 70* out...


fwiw, I acutally remove fuel when it's hot like it should be, i have no heatsoak.

OK so I've got my car tuned fairly well, and I'm back on the subject of IAT related fuel conditions.. For a while i've had IAT/CLT correction disabled entirely, and it's worked fairly well.

I did notice though, that varying temps caused rich / lean conditions -- but in the opposite direction of what you may think.. One would imagine that in cooler environments your car would run more lean because of the increased air density relative to static fueling. However, i'm seeing that the car runs richer -- and i think i know why.

If you change one of the gauges (or go to real time display) you can see the "gamma enrichment", which in my case was less than 100, despite the IAT/CLT being turned off.

When checking under Megalogviewer, i see that GAIR correction corrseponded to the gammae that i was seeing (though annoyingly i can't find a gair gauge in megatune!).

Anyway -- i htink that the gAIR formula is a little off, because it's pulling significant amounts of fuel (5%), and the IATs were only reading mid 80s today...

SO -- has anyone verified that the formula is correct? Has anyone tweaked it? What wold happen if i just made it flat to avoid any correctiosn? (and alsso, how would i do this hehe)

[EDIT] -- i read this page:
http://www.bgsoflex.com/megasquirttherm.html

Based on that info, my initial idea seems to be correct... the airdenfactor.inc seems to be incorrect, in that it is overcompensating in both the rich & lean directions...

how can i verify that my IAT sensor is reading correctly? would dunking my sensor in various temperature glasses of water and then checking the resistance work?

-Tomaj

IAT in the End tank ftw.

I still have heat soak on hot starts, but that lasts only as long as it takes to get some air flowing past the IAT.

You can drill and tap your end tank using the same tools you used for your oil pan and screw the sensor in. bickity bam problem solved.

I'm swapping my IC this weekend and highly considering this. Just gotta find my tap.... My new IC is 7" longer and will eliminate the small pipe I currently have my AIT residing in.

Nothing really to consider unless the metal your IC is made out of is super thin, mine is an ebay IC and was thicker than my oil pan so its working great. Just spread some RTV on the threads when you thread it in :)

I have a love/hate relationship with RTV.

my problem is the lack of the 3/8npt tap floating around. I'm pretty sure I let someone borrow it.

ok so aside from getting the most 'up to date' temp readings, is there a real fix?

I googled airdenfactor and found some guy with a firebird who said his MS was overcorrecting so he just reduced the adjustments and burned it.




I guess i'm just looking for someone to tell me whether what i'm saying makes sense.

Is the "iat / clt correction" (forget the exact name) basically a bandaid to be able to manipulate the gAIR without having to re-burn each time? If so, I can live with that.. i'll just mimic the range in my airdenfactor and add corresponding but inverse adjustments at 50% of the correction value..

In other words, what i propose is this... In the airdenfactor file, i would say for temperature 100 degrees, 90T, so a 10% reduction. I could then add into my clt/iat table, an entry for 100 degrees, adding 5% fuel, so on so forth..

make sense?