Willie

Does anyone know what the stock setting for these two constants are?

Min. Cool. Temp for Closed Loop
Min. Cool. Temp for Closed Loop, Cold MAT

Mine is not the stock tune. I bought the car like this. Mine are set at 50.00 and 149.75 degrees Celsius, respectively. I believe this means I'll never go to closed loop? Am I right or completely off base?

Willie

Kevin Blown 95 TA

The ones I have from a couple different 95 files are 32.75C & 59.75C.

Your car will run hotter than 50C (122F coolant temp) so it should go into closed loop based on that, but I'm not sure why the other one is set the way it is or what it even does - MAT - manifold air temp and since we don't have a manifold temp sensor I'm not sure how it is used unless it is for a different car. Maybe someone else will be able to answer that one...

Injuneer

MAT = IAT ?????

This is what the LT1_Edit tuning guide indicates:

It would appear that as long as you are operating below the value entered for MAT, it will go into closed loop at 50*C = 122*F, but only of the LT1_Edit "below" condition has the same meaning as your tuning software's (Tunercat?) "Min. Cool. Temp for Closed Loop". The "Cold MAT" qualifier is confusing.

Willie

Thanks for your input guys.

MAT = IAT ?????
I was thinking the same thing.

Now I'm confused on one point. "Min. Cool. Temp for Closed Loop, Cold MAT". To me, this implies any temp ABOVE the minimum for closed loop. But you're telling me the LT1 Edit tuning guide says just the opposite, "....as long as you are operating BELOW the value entered for MAT". If it was below, shouldn't it read, "Maximum Cool. Temp for Closed Loop, Cold MAT"?

Where do I obtain a copy of the LT1 Edit Tuning Guide? I know this is meant for OBD-I (I have OBD-II) but because the Jet DST tuning software includes absolutely no guides and they supply zero technical phone support, I'd like a copy of this tuning guide -- it's far better than nothing.

Willie

Injuneer

It's linked on the LT1_Edit website.

CARPUTING.COM

Andrew at AKM Electronics also has some good links:

AKM Electronics Home Page

I had the same question about the "Cold MAT" designation that you had, and I mentioned it in my post.

Would seem the easiest thing to do would be to simply observe whether it's going into closed loop when the CLT exceeds 122*F (and the O2 sensors are hot, and the timer from startup has timed out). If the short terms (which will be at 128 = 0% in closed loop) start to move above and below 128 (or +/- % in some OBD-II scanners), and the O2 sensors start to vary rapidly between 0xx-9xx mV, you know it's gone into closed loop. Some scanners can read the "closed loop" and "learning enabled" flags as well.

bobdec

According to Tunercat : You use 'Min Coolant temp for Closed Loop" (32.5*C) 90*F normally, and 'Min Coolant temp for Closed Loop - Cold MAT" (59.75* C) 140* F when the MAT (IAC in LT1) is cold. Unfortunately that cold temp is not published so it makes it difficult to know when 'Cold MAT' applies. So to give a general answer....on a very cold day if your IAT stays below the 'Cold MAT' mystery temperature you will never go into closed loop with your current tune as you will never hit (149* C) 300* F coolant temp. Whereas a normal car on tha same cold day would go into closed loop at 140* F. I suggest changing tune to match Kevin's post #2 as they are the factory settings. Living in Tucson you may not hit that cold condition to often anyways..