Running open-loop at all times. ok or bad idea? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 10-17-2008, 08:31 AM   #1
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Default Running open-loop at all times. ok or bad idea?

I shall explain myself further on if I need to, but just to keep the question simple;
is it a bad idea if I set MS to open-loop 100% of the time?
I have a MSPNP 9495 running Hires 10g.

I have my VE and spark tables to what I am happy with.

If it is not a bad idea, what is the safest way to do it?

What I was thinking of doing, without changing any settings in the configurator, is to change the following parameteres in EGO settings under "basic settings" tab:
- Controller step size: set to 0%
- Controller authority: set to 0%
- active above coolant temp: set to something unreachable like 250degrees Fahrenheit
- 'active above RPM': set it to over 8,000RPM

Any advice and criticism, preferably constructive, muchly appreciated

Cheers

Andrew

PS: fuel economy is NOT an issue

PPS: my engine is only a mildly tuned naturally aspirated BP (NA8) with stock internals
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Old 10-17-2008, 08:33 AM   #2
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i run open loop on my squirted miatas. i trust my tune.
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Old 10-17-2008, 08:43 AM   #3
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What's the safest way to do it Paul? ie. what settings/parameters have you changed, and what to? Please
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Old 10-17-2008, 09:00 AM   #4
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I ran open loop for the last year, and only went to closed loop for emissions.

I would never run closed loop in boost, but there's really no downside to allowing correction at cruise, assuming the target is what you've actually tuned your ve table for.
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Old 10-17-2008, 03:29 PM   #5
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Quote:
Originally Posted by OZMX-5 View Post
- Controller step size: set to 0%
- Controller authority: set to 0%
- active above coolant temp: set to something unreachable like 250degrees Fahrenheit
- 'active above RPM': set it to over 8,000RPM
You don't need to do all of those to turn it off. Any one of them would be sufficient. I just set the authority to 0 and leave everything else, so if I want to re-enable EGO correction I only have to change one number back.
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Old 10-17-2008, 05:28 PM   #6
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Quote:
Originally Posted by Ben View Post
I ran open loop for the last year, and only went to closed loop for emissions.

I would never run closed loop in boost, but there's really no downside to allowing correction at cruise, assuming the target is what you've actually tuned your ve table for.
I thought it was better to run closed in loop for that reason, to prevent it from tweaking fuel while in boost and only sticking to the table.

I run open loop up to 100kpa but correct only from 1000rpm, then closed loop in boost.
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Old 10-17-2008, 05:30 PM   #7
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you got em backward i think sam.
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Old 10-17-2008, 05:32 PM   #8
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Nope, most EMS systems are not capable of running closed loop in boost in a manner that would work well. Think about how a PID controller works.
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Old 10-17-2008, 09:00 PM   #9
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So do I have it backwards?
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Old 10-17-2008, 09:25 PM   #10
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Hopefully I am right here but here goes:

In Open loop the ECU bases fueling on the data in your fuel tables with no regard for what your actual AFR is. No O2 sensor input

In Closed loop the ECU uses your fuel table and data from your O2 sensor to adjust fuel to match your AFR targets.
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Old 10-18-2008, 05:28 AM   #11
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I'm drunk, so excuse the absurd pre-school style conversations.

open loop
ECU: Sup O2 sensor.
O2 sensor: Sup ECU. You're a little too lean.
ECU: No **** you O2 sensor.

closed loop
ECU: Sup O2 sensor.
O2 sensor: Sup ECU. You're a little too lean.
ECU: OK, we'll add some fuel to that ****.
O2 sensor. C00l.
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Old 10-18-2008, 05:34 AM   #12
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Quote:
Originally Posted by Savington View Post
I'm drunk, so excuse the absurd pre-school style conversations.

open loop
ECU: Sup O2 sensor.
O2 sensor: Sup ECU. You're a little too lean.
ECU: No **** you O2 sensor.

closed loop
ECU: Sup O2 sensor.
O2 sensor: Sup ECU. You're a little too lean.
ECU: OK, we'll add some fuel to that ****.
O2 sensor. C00l.
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Old 10-18-2008, 07:07 AM   #13
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Red face


can't wait to read your version of a tuning manual Savington
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