TT_Vert

iTrader: (12)

My LTIT is -11.5 yet my STIT is 8.5 or so. I would think the positive STIT would bring the LTIT down but it doesn't seem to be. It seems the LTIT is sticking to it's guns so to speak and pulling fuel while the STIT is adding fuel. Does this mean that my actually RAF correction is -3 g/sec? All the while my AFR error is nearly perfect at .80% lean at 14.75AFR when commanding 14.62. I've been playing w/ the RAF table a bit but I'm a bit confused. Am I not understanding the idle trims properly perhaps?
Dave

Russ K

iTrader: (1)

STIT & LTIT are not fuel trims. They are the adaptive idle speed trims. The LTIT's are not enabled until 176*F on a stock tune, and then they move very slowly.

And, yes the overall correction is -3g/sec. So your RAF table needs to be lowered by 3 g/sec.

Russ Kemp

TT_Vert

iTrader: (12)

I understand it isn't a fueling trim but if the RAF is reducing airflow at idle by the STIT that means it is going to richen the mixture when in open loop no, lets say during a warm restart before o2s start switching? How slow moving is the LTIT? I did some real time tuning of the RAF table and it moved VERY quickly when I was watching it and playing w/ the RAF table. For example I'd be at an LTIT of -10 and I'd decrease the RAF table by .01 lb/min (6 lb/hr) and the STIT would shoot way positive and the LTIT would fairly quickly drop into the negative area. I'd say about a rate of one percent in 15 seconds.

Would it be of any benefit to lower the ECT for implementation of the RAF table?

Thanks for the input


Dave

Russ K

iTrader: (1)

The RAF table doesn't change the fueling. If the airflow is reduced, then the pcm will command less fuel and if the airflow is increased, the pcm will command more fuel. Regardless the pcm is in open or closed loop.

I only lower the adaptive idle temp if a 160*F stat is used. So around 155*F. You don't want the LTIT to learn at cold engine temps.

Russ Kemp