I've been eye-balling that thing all day.. There are two unused vacuum ports on the passenger side that I have capped.. one is way small, the other though- it could possibly be tapped to put the sensor there.. The adapter plate, well hell- I never thought of that to be honest.. I'll give it a look..

12.7 to 12.9 is what HemiFever was aiming for.. that is with a safety margin though.. leaning out on a WOT engine would be ugly- nice little melted holes in pistons and such.. I think optimum is 13.3:1.. in this circumstance, I'd rather be a touch rich than a touch lean..

I rarely go above 3.5kRPM in any circumstance though- which means it doesn't leave closed loop once i've reached operational range.. the sensors are pushing/pulling fuel more than the script I'm thinking..

the PCM doesn't have a wide variance when it comes to pulling/adding fuel.. it's actually pretty tight according to what I'm reading.. this is the reason the baseline (programmed duty cycle) has to be close.. then the 'puter can add or pull minutely to adjust to environments.. In my case, and due to the AIT (my suspicion) it is adding when it doesn't need to..

I appreciate all the help so far guys! You guys are helping me think this through and understand it better.

 

O2 sensor has the final say on mixture ratios.

Moving the IAT is certainly a good plan though, if your are looking for the ideal. Lots of folks move them to where the air is cooler, to GET The motor to run a little richer. You are the first person I have seen trying to get it to read the warmer temps.

 

according to the usb/obdII, the intake temperature is silly cool after the ram air hood compared to before.. I'm sure it actually is cooler, but I'd just like to see what would happen if I fooled the engine into thinking it was warmer- and in regard to mileage.. I didn't want to screw anything up by doing this though.

 

maybe you could mount the AIT remotely for testing purposes. You could heat it in a controlled fashion to gather data about what happens to the USB/OBDII readings under different driving conditions. Maybe you could home in on an optimum temperature with respect to something known like coolant temperature to help give you an idea about optimal placement.

 

I'm going to do just that Ugly..

what I'm thinking though, is it won't be an instantaneous result, even with accurate real time readings- the computer will have to learn whats happening and adjust or re-write the tables (well, those that is can alter).. in closed loop- I don't know what'll happen.. likely, it will pull fuel- but will it be enough to warrant all this pontificating? dunno..

I'm not about to say those damn chips that do (in principle) what I'm suggesting actually work- because they do a resistance and then that is it.. w/o a varying resistance the 'puter learns around it in short order.. I'm thinking, in my circumstances which are a little different than most, the trick may work.. I ain't looking for 50 ponies and 20mpg- that is crazy, but bump me a single mpg and trick the 'puter into advancing timing? I'd be happy with that!


my next thread is going to **** some folks off.. but damn- it is going to be based on advancing fuel sync +3~5 degrees w/ the 1.7rr's.. I've recently read where this is a VERY good thing to do in terms of power and mileage- and that fuel sync is the one thing the PCM will NOT do on the fly..

 

It all depends on how fancy you're getting temperature resolution wise. We are at a real disadvantage not knowing for sure exactly how the computer uses the AIT sensor data it collects how often it collects it etc.

I'm pretty sure a sensor like ur AIT sensors will what I'd consider to be pretty damn slow responding, aka probably don't and aren't ecpected to respond in units of time measured in less than quantities of minutes.

As long as you could tracks sensor locations temps within 10deg f/min or so of actual engine locations I'm sure you're within the ball park of simulating at a level the engine cpu is likely to be designed to respond to.

 

The PCM pays attention to all its sensors, and polls them MANY times per second. The data you see on your scanner is just a snapshot, given the relatively slow data rate of the communications bus you are dealing with. (It is close enough to 'real time' for human minds, that it just doesn't matter much....)

I would expect that doing your experiment with the IAT (Intake Air Temp) sensor would indeed have pretty much an instantaneous effect on fuel mixture...... as that is one of the require sensors to determine mass air flow. (yep, I am backpedaling on my previous statement that you don't really need it.) However, what you are looking for is LONG TERM results. So, you would have to play with it for a while, to get meaningful data.

The chips that are advertised run a resistor in series with the sensor, giving the pcm an artificially low temp reading. (proportional to actual reading.....) Until the PCM adapts to the changed situation, you might get a pony or three out of it...... but, that's it.

 

I read an article some 'brrrittishhh fellow' wrote about the concepts.. it makes sense, but if it made near anything like the advertised BS of those chip marketers, why wouldn't the manufacturers do it?

I figured that out this morning.

Heading into work, with the IAT outside of the hat and dangling via zip-tie about 4" above the headers, I heard and felt something I haven't in a long long time- spark knock.. whoops.. I pulled in the station for me fuel (I'll take skoal straight and mt. dew, thank you) I put it back in the duct.. No more knock..

I made the mistake of shutting the laptop down yesterday.. For some reason, every time I shut it down and restart it I have to re-load drivers for that OBD-II reader thingy.. So, I wasn't taking any readings when all of this was happening..

discovery: that critter DOES have impact on a/f, and pretty much instantaneous as you said.. I'm not going to mess with it again, until I get the wb a/f installed and can monitor it more carefully and accurately.

 

I wonder if my IAT is on the fritz. I get a slight knock when I'm on the 91 tune with crappy 89 octane gas in the tank. The knock isn't near as bad as I've heard in other peoples trucks but it's there.

I think I'm running a little rich too because the other day I noticed soot on the rear quarter panels directly above my exhaust tips. I think it might have something to do with running the 91 tune for the last few months and maybe the Bosch o2 sensor is on the fritz as well.
I need to check out the resistance on the o2 sensor and map sensor then just swap the IAT.
I haven't put near as much thought into it as you have but this thread has got me wondering now because I only get about 11.5 mpg with 33" tires and 4.11 gears.

 

Hmm. Maybe hanging it by the header was making it think it's hotter than it is and the cpu leans out to compensate bringing on knock from being too lean. I'm surprised it responded so quickly. Most f the temp sensors I've dealt with are pretty slow.

It seems like since you were just leaving for work it must still have been in open loop. I wonder what would happen if you waited to move it by the headers until after in closed loop. Though that wouldn't be a very practical solution.