Forcefed86

iTrader: (4)

Working with a turbo LS engine. (done several now with the MS3 now). I usually end up flat lining the IAT/MAT table because of this which causes some issues Id like to avoid. Main issue is at start up the sensor is around ambient, and as the engine warms up the IAT rises. If I’m sitting in traffic on an 80* day my IAT temps can jump up to 125+ Then when I accelerate they drop rapidly closer to ambient again. THis causes the tune to bounce all over.

Temp sensor is mounted to the OEM plastic intake manifold, so it isn’t getting “heat soaked”. Are the generic supplied MS3 settings for the MAT table geared towards reading ambient temps only? Seems like I’d have to place the IAT sensor in an isolated “cold air” intake tube to work properly.

That said since this is a turbo build I use the IAT charge temps to pull timing so installing the sensor externally isn’t really an option either. In this case would it be better to place another IAT outside the charge pipe for cruising SD calculations. And use a second IAT sensor in the charge pipe to pull timing?

The EGO and auto tune seems to take up the slack if I just zero the MAT table, but that seems like a half *** way of doing it.

What’s the solution here?

Nathaninwa

The stock, or correct air temp curve is wrong for real life I've found. I've got a curve in my street 2j car that works well and seems to well in my LS car. Give me your email and I'll send you a tune

subeone

iTrader: (5)

oh, it'll get heat soaked if its in the intake mani.

you have it set up as a MAT; manifold air temp.

Put the IAT immediately post I/C.

Regardless, if your transient tables & "fuel stuck to the wall" tables (evap, boiling) are correct, you shouldn't have any issues with fluctuating air temp. (i call them evap and boiling because im not sure what ms3 labels these tables as, but since its a standalone its safe to assume it can use either map or tps based transient enrichment)

It's very difficult to get it dialed in, you could do as you have said and use 2 IAT's. 1 for ambient, and one for the manifold, and use the proper multiplier for each IAT to adjust fuel accordingly.

Nathaninwa

We can blend mat and clt for fueling and blend tps and map for accel and transient fueling

Forcefed86

iTrader: (4)

Huh I couldn't see the plastic OEM intakes heat soaking much. Nothing like a cast manifold anyway. Mine always seem relatively cool to the touch.

I was under the impression there was a pretty general set calculation for SD temperature VS fueling based on ideal gas law. And this curve is what's loaded into the base tunes.

First image is the supplied curve. Second is what I have been using. The modified table results in a much more linear tune, but can't be "right". With the original table if I started racing on a hot day and ambient temps dropped racing into the night, my fuel correction would be maxing out. Now at least it stays pretty close to the VE table regardless of the inlet temps. I rarely see over 155*

Nathaninwa

Email sent. I know the gas law is scientifically correct, but I found it just didn't work for me. I created a curve that works in my neck of the woods I guess. With a tune that was close, a friend and I drove for about 2 hours in all sorts of conditions with the average temp being 60% and then let ve analyzer do its magic. That 60* point became my new 100% and everything hinges on that number. Then as the nights got colder or days got hotter I kept track of O2 correction. When it got a little to far I'd adjust the air temp table to bring it back. It took a year to get this working, but back when I drove the 2j car on a daily basis, corrections are within 5% year round

JoeNova

I've never had an IAT in the plastic intake heat soak much above ambient. Where in the intake did you put it?