Forced Induction Supercharger/Turbocharger

Closed or Open Loop. Pros and cons of each

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Old May 27, 2009 | 05:15 PM
  #1  
RUNMYTA's Avatar
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From: Bristol, Tn
Closed or Open Loop. Pros and cons of each

Which do you prefer for higher boosted applications and why. I have talked to a couple different tuners and each has their own style. Which do you think is best for 10+PSI?
Old May 27, 2009 | 06:06 PM
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Assuming you are running the stock computer, you will always be in open loop while in boost. Well PE mode anyways. In WOT the o2 sensors are more or less ignored.

Only reason I would tell someone to tune open loop is a massive cam that won't idle at 14.7 afr.

With the MS I can run closed loop under any conditions - so if you trust your wideband it will add/remove fuel any time. I actually run closed loop close about 15.5 for idle and cruising.

WOT = wide open throttle
PE = Power enrichment mode

Last edited by jsetzer; May 27, 2009 at 11:28 PM.
Old May 27, 2009 | 09:13 PM
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MikeGyver's Avatar
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What he said. Closed lewp is a wonderful thing.
Old May 28, 2009 | 09:34 AM
  #4  
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In these days of the "green" people and high gas expense, having the gm pcm with closed loop mode to control part throttle stoic @ 14.7afr can help with fuel costs. So, I have tuned for WOT PEvs.RPM mode @ 12.8afr, and, 14.7afr for part throttle cruz with use of the MAF sensor. My app... 97ss MM6 383ci - D1 ~14/15psi OBD2. I still run the 1 bar MAP sensor, so, the PCM cal is a custom tune with use of a DynoJet WB.

This was my approach, but, you can also get very close to stoic with a speed_density control system with a bit more tuning work.
HTH B.
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