Yet Another CRX HF

[cfg83]

mrmad -

Originally Posted by mrmad

(cfg83 says)"What do you think of the WAI/HAI? I think it's a "clean" way of moving closer to lean-burn because for some drivetrains, you are "pushing" the ECU/PCM to decide to go into a lean-burn mode."

Not sure what you mean here. Isn't anything that leans the AFR beyond the stiochiometric ratio, whether it is a WAI/HAI or a reprogrammed ECU, going to raise the NOx emissions?

That's what I want to know. I think it is "cleaner" because you are simulating a real driving condition (the car in hot dry climates like Arizona in the summer) that the car was designed to operate in.

But that's why I am asking, I want your opinion.

CarloSW2

[SVOboy]

IAT mod creates lean burn, HAI does not.

[mrmad]

"IAT mod creates lean burn, HAI does not."

I think you're right and possibly wrong.

It would depend on the car and how the OEM ECU is programmed. Ultimately, in closed loop (at low throttle settings), most ECUs are attempting to keep the AFU at the stoichiometric ratio (14.7) by monitoring the O2 sensor. So in closed loop, a HAI should not have an effect on the mixture.

Since the O2 sensor is not sensitive enough at higher throttle settings, the ECU goes into open loop, where it is reading from tables. If the ECU is programmed to be adjusting the tables from IAT, then an HAI would be affecting how lean/rich the mixture is. If it is not, then it wouldn't.

[omgwtfbyobbq]

Exactly. So in stop and go city driving with near WOT, the car can be running leaner for a good chunk of time. This can also be accomplished by adjusting the AFM. The HAI/WAI deal should allow fewer pumping losses because the incoming air has greater energy/volume, but for most engine operation this is already addressed via EGR, i.e. hot exhaust air with little oxygen, being directed into the intake. The practical limitations have to do with the distribution of EGR/air at low loads, which can mean uneven combustion, and the hot EGR igniting the gas before the spark which results in pinging/detonation.

[mrmad]

What made me interested into converting to Megasquirt is that you can set a closed loop target AFR above 14.7. The car would essentiall be in a "lean burn" mode all the time at low throttle settings. This may be possible with a chipped ECU, I haven't looked into them that far yet. Most applications I've seen for chipped ECUs are for high performance applications and they are turning off closed loop altogether.

As strict as CA emissions are, luckily they let you "pre test" your car, meaning if you think your car may fail emissions, you can get it smog tested without the information being sent to Sacramento. If I do get a Megasquirt in the car and lean it out, I intend to have it pretested to see how much the NOx emissions have increased in an effort to keep it within legal limits.

[cfg83]

mrmad -

Originally Posted by mrmad

What made me interested into converting to Megasquirt is that you can set a closed loop target AFR above 14.7. The car would essentiall be in a "lean burn" mode all the time at low throttle settings. This may be possible with a chipped ECU, I haven't looked into them that far yet. Most applications I've seen for chipped ECUs are for high performance applications and they are turning off closed loop altogether.

As strict as CA emissions are, luckily they let you "pre test" your car, meaning if you think your car may fail emissions, you can get it smog tested without the information being sent to Sacramento. If I do get a Megasquirt in the car and lean it out, I intend to have it pretested to see how much the NOx emissions have increased in an effort to keep it within legal limits.

One thing that I have regretted about getting the ScanGauge is that it is very easy to use, but whets your appetite to do more. If I knew then what I know today, I would probably have looked around for something that combines the functionality of both of these :

http://www.apexi-usa.com/product_ele...=260&pageNum=1
http://www.apexi-usa.com/product_ele...=199&pageNum=1

This is what DRW has in his 1990 Laser :

http://www.gassavers.org/garage/view/207

I looked in the Garage, and I can't find anyone with a MegaSquirt installed, so you would be a GasSaver Pioneer.

CarloSW2