Warm Up Enrichment - how much do you run at what temps?

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MotoFab
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Re: Warm Up Enrichment - how much do you run at what temps?

Post by MotoFab »

The cars and motorcycles I've checked go into a closed loop idle within about 30 seconds after the motor is started at ambient. O2 sensors, Narrow Band and Wide Band both, have an internal electric heater that allow them to operate with no additional heat. The sensing element reaches operating temperature in a few seconds. Wide band controllers measure the temperature of the sensing element and account for it in real time. It's true that wide band controllers may be poorly designed, but the output can still be used to control the mixture at idle.

Closed-loop control for a roughly 14.7 mixture at idle, or at a constant RPM, can also be done without an O2 sensor. The mixture can be leaned and richened while the ECU evaluates changes in crank angle velocity caused by the changing mixture. You can get pretty close to the best power, 14.7, or best economy ratios, without an O2 sensor.
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Re: Warm Up Enrichment - how much do you run at what temps?

Post by Fred »

All true, too. The goal has to be to have a tune that drifts minmimally away from perfect under any reasonable circumstances and only use the wbo2 sensor setup to double check that or fine tune it for specific purposes.
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Re: Warm Up Enrichment - how much do you run at what temps?

Post by MotoFab »

Since warm up is the topic, 14.7 is great for warm up. It usually makes the hottest CHTs. Also, wagging the mixture above and below 14.7 every second or two is the only way to operate a catalyst. Not that many folks are running catalysts.

But, did you mean the 14.7 ratio is the intended result full-time? If so I didn't realize that. I was thinking the intention with aftermarket ECUs generally is for a best economy ratio at steady state, and a best power during acceleration. I mean, development usually starts with a single fuel map, then progress to dual or multiple fuel maps.
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Re: Warm Up Enrichment - how much do you run at what temps?

Post by Fred »

MotoFab wrote:I mean, development usually starts with a single fuel map, then progress to dual or multiple fuel maps.
False. Furthermore, all the stuff about 14.7 is not only generally wrong for a random fuel, but generally wrong as it's up to the user/owner which AFR/Lambda they want to run. This thread is to discuss the best simple model for adding extra fuel to account for the various affects coldness has on engine performance. Let's keep it on topic, thanks. Don't reply to this message, either, more wasted space...

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Re: Warm Up Enrichment - how much do you run at what temps?

Post by MotoFab »

Re: "... simple model for adding extra fuel to account for the various affects coldness has on engine performance."

Say it turns out that for whatever reason you don't use the O2 sensor signal when the motor is cold and idling. As I was saying before, even without an O2 sensor the mixture can be closely adjusted.

Make small changes to the injector period while monitoring changes in crank angle velocity caused by the changing mixture. As the mixture ratio is continually changed, in either direction, at some point combustion becomes irregular. From our conversation, it seems like the code will be monitoring tooth-to-tooth periods, so the crank velocity data will be there.
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Re: Warm Up Enrichment - how much do you run at what temps?

Post by jbelanger »

MotoFab wrote:Re: "... simple model for adding extra fuel to account for the various affects coldness has on engine performance."

Say it turns out that for whatever reason you don't use the O2 sensor signal when the motor is cold and idling. As I was saying before, even without an O2 sensor the mixture can be closely adjusted.

Make small changes to the injector period while monitoring changes in crank angle velocity caused by the changing mixture. As the mixture ratio is continually changed, in either direction, at some point combustion becomes irregular. From our conversation, it seems like the code will be monitoring tooth-to-tooth periods, so the crank velocity data will be there.
But that assumes the load on the engine doesn't change. If it changes then you don't know if the angular velocity change is due to the pulse width change or the load change. So it might be ok in a static situation but not for dynamic adjustment.

But I could be missing something.

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Re: Warm Up Enrichment - how much do you run at what temps?

Post by Fred »

You're both off-topic! This is about how we configure what we want the fueling to look like, not how to go about achieving it! No more! I was just about to delete Jim's post, but I'll leave it with your response now. Next OT post will be gone.
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