CAI at High Altitude and Requisite Tuning

[c2fx]

So a philosophical question for all those smarter than me out there. I live at 6600' and the tracks around here are generally at 5000' or a bit higher. The atmosphere here kills n/a engines and looking to try and rectify that. i know, the computer will adjust fuel delivery to ensure a proper a/f, utilizing data from the o2 sensors.

My question is this...some of the CAIs require a tune following installation. Would this be the case for me at altitude since I'm already operating in a reduced atmospheric?

At sea level, I'm assuming the ECU needs a tune when it now has to account for the increased air flow, and corresponding fuel delivery. Just curious if, at altitude, doubtful I'd still be surpassing the air flow at sea level with the CAI. Lastly, how would I know if I need a tune after I install a CAI? Engine codes?

Lengthy post, but hopefully it makes sense. Appreciate any feedback.

Matt

 

[JAJ]

A CAI requires a tune if the diameter of the intake duct tube is different than stock. The MAF sensor reads the airspeed in the duct, so a fatter duct has lower airspeed with the same airflow, causing the sensor to report less air than is actually flowing. A tune corrects the sensor readings so they reflect real mass air flow again. As for correcting for additional airflow because of the bigger duct, there's usually enough headroom/safety margin in the factory calibration to handle a little more airflow without a problem.

 

[c2fx]

ok, so its more about airspeed than maintaining proper a/f ratios...i had not thought about it in those terms.

 

[JAJ]

ok, so its more about airspeed than maintaining proper a/f ratios...i had not thought about it in those terms.

It's all about the A/F ratio, and here's how the ECU does it: The MAF sensor measures "Mass Air Flow", which is the number of pounds of air per minute entering the engine. From knowing how many pounds of air are going in, the ECU calculates how many pounds of fuel to supply to match the incoming air. Pretty simple, really.

What I was explaining is that the way the MAF sensor measures air mass is to measure the temperature and speed of the moving air in a tube of a specific diameter. A given mass flow will move faster if the tube is smaller, slower if it's larger. When you change the tube size, you have to recalibrate the sensor settings in the ECU.

 

[c2fx]

that all makes sense. thanks! i am more of a carb and pushrod guy, so going through some learning here...

 

[TymeSlayer]

Been running here in CO with a 84.5 TB and AiRaid CAI - without a tune for years. Zero issues. The AiRaid version does come with a Venturi tube that's required without a tune.

 

[c2fx]

Appreciate the feedback tymeslayer. Just trying to work through the winter to do's. Between the Boss and my '70 sports roof, it's going to be a busy offseason!