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  #25  
Old 03-03-2011, 02:13 PM
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Re: CAI give actual performance or MPG improvements?

I agree that in order to take full advantage of mods: CAI, exhaust, larger throttle body, bigger injectors, larger fuel pumps, the ECU has to be reprogrammed.
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  #26  
Old 03-03-2011, 08:02 PM
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Re: CAI give actual performance or MPG improvements?

I agree with what is being said. Either way, the engine works less trying to 'get' air. Will the ECU reprogram to wanna work harder?
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  #27  
Old 03-04-2011, 12:02 PM
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Re: CAI give actual performance or MPG improvements?

Both tangents are correct, related but different.
Maybe a brief explanation would help clarify.
The ECM controls tuning parameters as long as conditions remain within the ECM matrix (table of values). If you go outside ECM limits for an extended time period it will trigger the SEL. In this situation, it would be related to a Lean or Rich Code to trigger the light. The ECM is readjusting itself constantly based on input readings & output sensors to stay within the OEM programmed operating range. An ECM Programmer used to reprogram ECM will allow shifting the matrix values and/or flashing a totally different matrix based on desired tuning.

The ECM programmers don’t modify the sensors, injectors or any physical hardware; it reprograms the matrix values that will be sent or received as normal. Longer Injector pulse, coil pak duration, ignition timing, etc. Thus Indicating the ECM has control and attempts to retain control within programmed parameters.



The other variable that ProShop01 is discussing is volumetric efficiency (VE), and the ability of the Intake Stroke to charge the cylinder; which is effected by 1) physical time (RPM) of engine and 2) Intake Track & Assoc Restrictions. The higher the RPM the shorter the physical time to cylinder charge. The higher the restriction results in lower pressure & available volume to retain a stable pressure flow of air within the Intake track. Observing a Vacuum Gauge or Boost Gauge demonstrates this clearly.



Improving the Intake track improves the #2 variable and in-turn benefits #1 variable by keeping intake track with higher air pressure... thus more volume available for cylinder charging. Naturally aspirated engines have limits based on these pressures.

 Improving the Intake Charging is provided by a CAI system, it will "provide" more Air Volume and... for a short time the ECM Matrix will react to the leaner mixture with additional fuel pulse time or freq of fuel injectors providing a little more power. The ECM will shift the ECM Matrix to adjust for the Air Volume & Density until it “returns” the values back to programmed values. Similar to changing altitude, driving on a cool evening, rainy mist, foggy evenings... all these will change air volume & density and will change performance for short time until ECM readjusts matrix values.

The CAI will improve VE, although the improved VE & associated increase in volume of Air (O2) will not be utilized as an improvement in power until ECM is reprogrammed. The VE may change MAF & TSP readings, essentially requiring less TSP opening for a given RPM, but bHP will remain the same. Again, similar to how a cool foggy night allows the engine to perform a little better for a short distance.
Prior to ECM controlled Engines, this would provide an increase in HP & Power.

The use of CAI, Catback Exhaust without ECM Programmer provides a benefit mainly in “sound” and emotions. The use of a ECM Programmer without the other 2 provides minimal improvements in power, but will correct other parameters.
The use of all 3 will provide a significant performance gain, but Cost of HP or Cost of MPG gains may not be economical or provide return of value. I personally will utilize all 3 on my WK2; I want the sound, I enjoy the little extra power, and I’ll gladly accept any slight improvement of MPG when foot is not heavy! But Cost of all 3 won’t be returned in MGP Savings or Life of Engine.

Opps, sorry… my brief grew slightly… but that’s my 4 cents worth!
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Old 03-04-2011, 01:59 PM
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Re: CAI give actual performance or MPG improvements?

^dougc, my eyes may have started to bleed a bit mid-way through, but you get a +rep for a strong brief and checkered flag at the end
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  #29  
Old 03-04-2011, 02:57 PM
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Re: CAI give actual performance or MPG improvements?

Great explanation but there will still be benefits during WOT instances becuase it goes open loop and the values are predetermined. Normal driving though is explained spot on above.
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  #30  
Old 03-04-2011, 03:42 PM
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Re: CAI give actual performance or MPG improvements?

Quote:
Originally Posted by mrpositraction View Post
Great explanation but there will still be benefits during WOT instances becuase it goes open loop and the values are predetermined. Normal driving though is explained spot on above.
You are correct, benefits would be more noticeable on WOT Open Loop. All modes of Open Loop utilize predetermined Inj Pulse & Spark Timing as examples.

Cold, Failsafe & WOT Open Loop modes utilize different predetermined settings. Improvement is noticeable, but would still benefit from ECM Programming if the Presets are re-programable too. WOT is based on a full Rich mixture A/F... based on OEM Spec configuration. An increase in Intake VE and reduced pressure to exhale would essentially lower the fixed Rich Mixture A/F ratio based on OEM presets. Increasing the WOT preset would increase the Fixed Rich Mix A/F ratio as well.

I am not familiar with Mopar ECM & available variables for reprogramming, but I'm confident it's similar to GM ECM logic. If similar, the "fixed" Open Loop values can also be increased to provide additional gains.
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  #31  
Old 03-04-2011, 03:57 PM
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Re: CAI give actual performance or MPG improvements?

Adding N2O is a alternate method to increase Intake VE, O2 Density & Volume by injecting O2 via a cold liquid transformed to gas that also absorbs heat as a extra benefit. So much O2 is added that WOT Rich Mix A/F would still be Lean and totally outside of adjustable parameters. Fuel Pump & Fuel Nozzles are added to calculated Fix Values for correct Rich Mix A/F. All WOT runs need the mix calculated based on modified parameters. Don't mean to get off track... but it's another WOT variable example.
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  #32  
Old 03-04-2011, 05:28 PM
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Re: CAI give actual performance or MPG improvements?

Great explanation Dougcjohn! Sells me on the idea of buying the programmer and exhuast next. Not sure what the wife will think. What's a couple grand more after paying this much already.
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