you see your map? under vacuum at high temps i see 40% fuel added! air temp is added into the haltech's VE calculation, so if all cells are set to "0" it uses its calculation with rpm, pressure, temperature, VE, etc to calculate fuel. your corrections are of course on top of what the haltech is calculating. So the haltech is pulling fuel out due to the high temps, and your map is set to ADD tons of fuel to counteract what the haltech is reading because the temp it is reading is incorrect. When the temps are right, the haltech calcs seem to be dead on, needed a near "0" correction, but your map has been set up to keep that false reading from causing a lean condition. This is exactly what I had to do in my map, I just don't like that because its not a true reading, you're just compensating for an incorrect reading. The problem there is, if you boost while the sensor is still heat soaked (at 212 degrees Fahrenheit for instance) your correction will go from +40 to -4, causing you to be lean under boost! Because while the sensor hasn't cooled off yet, the incoming air has (it moves at an extremely high velocity!)
i know you know haltech extremely well rich, maybe this is a misunderstanding, but i just want to make sure we're both on the same page, because it seem like many people are confused on how the temp corrections work. with everything set to "0" temp corrections are still taking place!

ross

 

Ah, I see your logic now, but I don't think it's valid because I don't believe the Haltech is using ATS to correct fueling other than the table I posted. It's faking true VE tuning if you're a purist I guess. I currently use IPW for tuning. I know exactly what the fuel injectors are seeing at a specific load/rpm site and it is constant if that table I posted is zero'd out, whether it is cold or hot. That table is the only air temp correction going on as far as I know regardless of tuning method used. I think this is by design exactly for this reason - it's not fake - it's an empirical correction required that cannot be easily predicted based on mathematical calculation, but it is real.

PS. I never get anywhere near 200 deg AIT - max around 150 on a hot summer day idling.

 

ok youre using IPW so this doesn't apply to you. Using VE tuning, the air temp is calculated along with the ve%, injector size, manifold pressure, etc. so the correction table is just adjusting the haltech's calculations, the the actual amount of temp correction. in theory it should correct perfectly with all cells at "0"

and yeah mines about 150 idling, the 200ish is watching the haltech after the car is shut off and all airflow has ceased. BTW i am OCD with tuning, my tune is never good enough for me

ross

 

Even for VE tuning, I don't believe air temperature is accounted for in any VE calculations that the Haltech performs. Only Engine Volume setting, Inj Flow Rate table, and Inj Dead Time table need to be accurate for the Haltech calculations. This is my understanding based on the documentation I have read (which fails to mention ATS calibration prior to VE tuning), but I have not confirmed with an engineer.

 

http://forums.haltech.com/viewtopic....rection#p29617

 

good test.... set all corrections to "0" then unplug the ait sensor. if there is no correction in the haltech calcs, the AFR will not change. If there is correction built in, car will go lean (VE). Little things like this that we can't always get a 100% answer on is why I'm attending the Haltech training seminar in a few weeks, i've got a few questions written down ready to ask!

BTW thanks for the fast responses!

ross

 

I see the posts and it looks like someone "confirmed" that VE does use air temp for fueling calculations but they don't specify how it was confirmed. I remain skeptical but open to the test you mention. A more encompassing test would be to move the air temp sensor out of the engine bay. I'm going to bet that your car will still go lean as the car heat soaks even if that temp sensor is measuring constant ambient temp.

EDIT: It's not explicit, but one of the users implies Scott at Haltech Aus may have offered that info and he is one of the engineers. That said, I think the ATS correction table is required to compensate for physical changes because of heat soak. If you move the air temp sensor out of the engine bay, even if air density calculations are being held constant due to constant temp, I believe you will run lean.

 

I'm willing to bet the opposite....
we shall see!

ross

 

The only reason I'm confident about it is because my car goes lean with IPW tuning and zero correction. Something is happening affecting fueling unrelated to what the Haltech is doing.

 

I made a video, I'll post it when I get back to te house. With the sensor unplugged it shows Its cold, 14 degrees in my case, and the afrs richen up to compensate with all corrections set to 0. I'll post it ASAP.

 

No need for vid (but appreciate sharing findings - thanks). So background ATS compensation going on with VE. BUT try letting the car idle with that plug disconnected and see if AFR goes lean.

 

From the same thread posted above.

 

That's why I indicated the above test. The corrections for air density will be minimal compared to what is happening during heat soak. *I think* If Ross finds that VE mode really corrects well just by moving the air temp sensor out of the engine bay, then I will switch to VE and do the same thing!

 

Does it matter where you put the water temp sensor? I just got my water temp gauge installed. My mechanic said he mounted it where it's the hottest. He told me if I see the temp at 215F it's normal because he mounted the senor on the hottest pipe?? I just drove the car home and it reads 215 in 5 minutes.

 

You want it in the coolant cross over pipe which would indicate the coolant temp as the coolant leaves the heads. This is the temperature you want to see as it will be the closest to the temp of the coolant inside the engine.

 

actually, sitting idling with NO a/f correction the a/f should go lean due to the increase in intake air temps being higher but the car not seeing the increased temps therefore keeping the fuel injection time the same. It just seems that taking all corrections away wouldn't cause the a/f to stay constant but to fluctuate more due to the actual air temp changes. maybe i'm confused though.

 

As temps go up, if injection time stays the same, the car will go rich. Less dense air, less oxygen, same amount of fuel.
As far as my test goes, I was mistaken when I said lean. I assumed unplugging the sensor would yield high temp readings on the haltech, decreasing fuel, but when I unplugged it it registered 14 degrees Fahrenheit so the haltech richened the mixture. Even with o2 correction enabled, which took out 10% fuel, the temp reading richened the mixture by over a full point (13.5) with atc table at 0. I imagine without the o2 correction it would go down to at least 12.5. I did record a video showing the test but haven't been on my computer to upload it, but if anyone is interested in seeing it I will post it.

Ross

 

^that's what should happen based on air density alone, but it's not what I have experienced to date (and that is using IPW). So how to explain?

 

i'm with raj. I was skeptical of the whole "adding fuel under hotter temps" until raj helped me setup my map like his and it worked so much better than pulling fuel with high temps.

There is some other mechanism besides only the air density at play here. maybe like raj says it has something to do with vaporization or such.

 

Speed density.

The density of a gas can not be calculated without the temperature taken into account.

From some testing on another platform converting to speed density with the factory ECU running things, it was found that it worked best by using an average of coolant temp (fuel vaporization) and air temp to get everything to work properly. At low airflow, temp used was weighted towards coolant temp 75% vs. 25%. At higher airflow the it swung back to the air temp 75% vs 25% of the coolant temp.

I've also seen fuel temperature used with good results rather than intake air temp.