I tried too back in the day, I always found the FI guys just wouldn't mess with it. Most radix tuned trucks had turned it off. I am very interested in the results here, with the new sensor.

 

First logs with the new IAT I have also set the BIAS to 1.0 in the first two columns of airflow.

Cold start. Start logging and a drive of about 30 minutes.


Shutdown and had lunch with my son. Startup and start logging. Drive about 30 minutes home. About 4% leaner. An improvement anyway.


I also had done a little romping on the way home. I have a histogram to show my commanded AFR. Look at the circled. Was just one romp but I'd forgotten about the bug, I call it, with 2bar HPT. Once the parameters are there for Boost fueling.... it can take as much as a full second to command the right AFR. Pisses me off!

 

The new IAT sensor defiantly reads differently. So far I'd say 10 to 15* hotter IAT's at similiar ambient temps.

Have my tune setup tomorrow to just disable the CCT modeling as Dewmanshu mentioned. I am getting nowhere tuning until I can get it settled with this heat soak.

Now I'm wondering what to do with the IAT. Which one is correct. Guess I could pull it out and just see which reads closer to ambient temps?

 

That'd be interesting, which one read closest to ambient. Heck, to me it be interesting which one read what with another thermometer in a test box of some kind. LOL Just a curious thing though. It is all relevant to a scale more so than a specific temp any way. If ya know what I mean. As long as it is quick reacting and consistent you should be able to tune around it. Just saying you could put it in your intake tube but you'd have to have a very very aggressive IAT advance table. LOL Very aggressive. Why don't you do that? Put the extra one in your intake and use another custom PID for it? That would be awesome. Use the data in excel to make a comparison graph of the two iat's.

 

hahahah. Yeah a test vehicle. Maybe someday but I just want to get it running for now. Guess it doesn't matter what the number is. It can be gotten around. I guess the test for which sensor to use would then be the better responding one. Put one in the truck so it will run, plug the hole up. The other in the fridge for a couple hours. Plug it up and scan how long takes to come to a steady state at ambient or I have a heat gun.

 

This is interesting. I did a histogram of AFR error X IAT X g/sec of the last logs I posted.

If I'm reading this right. Bias isn't doing anything as DC Justin mentioned. Generally the hotter the engine gets, The hotter the IAT's obviously, and the leaner it gets period.

You can track the progression from 100 to 170 IAT's. Rich at lower IAT's. Lean at Higher IAT's and about the same error accross air flow range (the bias table)

Now the question becomes.... what do you do in a tune to compensate in OL? Obviously fuel trims would compensate and there is an adder table in PE that I've seen no one play with but nothing besides the bias table in open loop? Of course +/- 5% is considered a good tune but I want to be closer in WOT. Guess I could call it acceptable in non PE areas and use the IAT talbe for PE.

 

I just want to say. GOOD WORK! keep it up I've been real curious to find a good solution to IAT's messing with fueling.

 

Okay more testing.

Scenerio. I started it up and logged from a cold start with the CCT modeling off. All idling only. I never touched the throttle. Parking brake on in Drive with a fan at least blowing air onto the air filter. Then once the engine was up to temp... hot I just changed the Bias to 0 - 100% toward IAT, 1 50/50 ECT and IAT, then finally 2 100% ECT.

The Bias does play a role in the fueling. I was really suprised at the Bias of 2 and 100% ECT. It went really lean.

Still thinking about how to approach the tuning.

 

FWW, I turned my cct back on, screw that!!! That idea lasted all of 20 miles. With it off I am not saying the lean heat soak goes away, but you'll definitely find better recovery and more stable heat soak afr's IMO. I'd assume the better recovery comes from the ALL IAT bias (default with it off) and the IAT gets back to operating temp quicker.

 

Its biased toward IAT with it off also, or so it says in the little HPT blog. Shows it in my little test also.