JDraper said:
Rocket, I do have an 02 bung welded into my exhaust pre-cat converter, and that's where the readings are taken. I don't trust sniffers and never have. Every vehicle that I do dyno work on, I put a bung into. I run it on a Land-Sea dyno (Most of the time. Occasionally on a Dynojet) using a heated O2 sensor. The C&L CAI does come with a larger MAF housing, but retains the stock MAF sensor.
I'm not a rookie at this either...been doing it for 25+ years....Most of my experience is in carbureted/non computer controlled vehicles, but the basic principles are the same.
Glad to hear your doing it right with the bung instead of the sniffer crap.
The larger MAS housing and stock MAS element is EXACTLY why your running leaner and thus need a recalibration. That is what I thought; which is why I asked. The A/F has nothing to do with the CAI itself. If only doing a CAI while retaining all stock MAS components including housing and element the A/F will remain the same though the airflow will be slightly increased and more dense when running a CAI, but the additional air will be accounted for. The bigger MAS housing is the EXACT reason why your A/F went lean, not the CAI.
JDraper said:
Most of my experience is in carbureted/non computer controlled vehicles, but the basic principles are the same.
Since you assume you know so much then you would understand that when moving to a bigger MAS housing your essentially throwing the stock MAS elements calibration off by changing to a housing with more volume flow. Think of it like this. The MAS element strives to heat the filament wire to a constant temperature. The wind moving through the housing at whatever velocity will cool it so the MAS adds voltage to keep the wire at the same temp. The MAS then measures this voltage and when this voltage is applied to a fixed sized housing and also the IATS and you get how much airflow just went throught the MAS and the vehicle will use that to generate other figures for spark and A/F.
In simpler terms picture two tubes. One 1 foot in diameter and the other 100 feet in diameter. Both have air flowing through them at 60 miles per hour. Both have the same MAS meter installed in them. Both MAS meters see 60 mph of air speed (thus making them think they are metering the same amount or air) though the 100 foot tube obviously is moving much much more air and if channelled into an engine (hypothetical engine) would obviously cause it to run lean because not only is there more air going into the engine, but it is also UNACCOUNTED FOR. The fact that it is unaccounted for is a critical factor between why a vehicle goes lean and why it does not when taking things in the context you and I have discussed.
You can have more air going into an engine and still not run lean as long as it is being accounted for properly. When a vehicle is tuned right, even taking such steps as switching to a smaller blower pulley to make more boost will not give cause for a retune as long as that additional air is being accounted for through the MAS meter and the fuel system is up to par. However, when dealing with forced induction it is best to play it ultrasafe due to other potentially harmful variables. With N/A applications there is less chance of volatility like within a blown system.
You may have been doing this for "25+ years" but you may want to have a better understanding about your vehicles engine and electronic systems before assuming you know what you talk about. Jeff, I don't mean this to be directed at you in a harsh manner, but you are talking to someone who knows their stuff and who also truly does understand that their is HUGE differences between FI cars and Carbed cars. While principle is still the same the execution and everything in between is mostly different and thus cannot be approached with quite the same mindset as another. Good day.
