Unsure How ECU can alter actual air flow in inlet manifold

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JohnDee68
Posts: 249
Joined: Fri Feb 02, 2018 7:05 pm
cars: L36 Vx Series 2 8/2002 Acclaim Wagon 3.8L ECOTEC II.
Location: South Australia

Unsure How ECU can alter actual air flow in inlet manifold

Post by JohnDee68 »

Hi,
Can someone shed some light on this please to hopefully help me to understand?

I presume this is something what is likely basic knowledge for anyone working in the automotive industry, but I am trying to learn and understand this for tuning purposes.

In TunerPro there are things like "Desired Idle Air Rate Vs RPM", "Desired Idle Air Rate Vs ECT", "Maximum Mass Air Rate Vs RPM”, “Idle Air Flow Rate Vs RPM", “Default Airflow Vs RPM & TPS%”. Am I to presume it is possible for an ECU to actually adjust the quantity of air coming in to the inlet manifold? Though I can’t see how it can on a fixed air intake piping, unless this is only possible during 0% throttle and is achieved using the IAC (Idle Air Controller)?
Dylan
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Joined: Mon Aug 02, 2010 6:35 pm
cars: VR Commodore V8

Re: Unsure How ECU can alter actual air flow in inlet manifo

Post by Dylan »

You're right between IAC, PCV and even FBW where fitted.
All can effect the desired airflow.
immortality
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Joined: Thu Apr 09, 2009 12:31 pm
cars: VH, VN, VS, VX

Re: Unsure How ECU can alter actual air flow in inlet manifo

Post by immortality »

Aren't some of those default tables that the PCM used to see if things are working as it should?
JohnDee68
Posts: 249
Joined: Fri Feb 02, 2018 7:05 pm
cars: L36 Vx Series 2 8/2002 Acclaim Wagon 3.8L ECOTEC II.
Location: South Australia

Re: Unsure How ECU can alter actual air flow in inlet manifo

Post by JohnDee68 »

Dylan wrote:You're right between IAC, PCV and even FBW where fitted.
All can effect the desired airflow.
Thanks,
What is FBW, that's a new term to me.
Dylan
Posts: 3355
Joined: Mon Aug 02, 2010 6:35 pm
cars: VR Commodore V8

Re: Unsure How ECU can alter actual air flow in inlet manifo

Post by Dylan »

Fly By Wire

Electronic throttle body, butterfly is an actuator.
JohnDee68
Posts: 249
Joined: Fri Feb 02, 2018 7:05 pm
cars: L36 Vx Series 2 8/2002 Acclaim Wagon 3.8L ECOTEC II.
Location: South Australia

Re: Unsure How ECU can alter actual air flow in inlet manifo

Post by JohnDee68 »

Dylan wrote:Fly By Wire

Electronic throttle body, butterfly is an actuator.
Thanks Dylan. Is that where the cars have the Throttle position sensor on the throttle pedal?
Dylan
Posts: 3355
Joined: Mon Aug 02, 2010 6:35 pm
cars: VR Commodore V8

Re: Unsure How ECU can alter actual air flow in inlet manifo

Post by Dylan »

Yes, dual channel feedback on the pedal for safety measures also software buffering between pedal position and butterfly position to change engine behavior. That's where things like I Drive units come into play.
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