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

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

Post by Fred »

You're trying to tell me that going down to the ignition limit of lean 17:1 or maybe lower, is going to cool the engine and still make good torque? I do not believe it at all. I'll give you a call shortly :-)

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

Post by EssEss »

MotoFab wrote:The full algorithm that is.
this sounds like gold - where do I find the details ? am I going to have to fire-up matlab to autogen a model for me - or is it simpiler than that ?
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Re: Warm Up Enrichment - how much do you run at what temps?

Post by MotoFab »

EssEss wrote:this sounds like gold - where do I find the details ? am I going to have to fire-up matlab to autogen a model for me - or is it simpiler than that ?
Here is the Toyota patent http://www.google.com/patents?vid=USPAT4388906
Note: Fig 5 has a typo on the X axis legend. It should read (x 10²mmHg) not (x 120²mmHg).

The math isn't so much the complex part, it's collecting enough samples to form an accurate integral of the manifold pressure. The vaporization formula needs an accurate history of the pressure the walled fuel was experiencing during the last combustion cycle, as well as other data or 2d interpolations.

I just refreshed my memory of the MAP vs. vaporized fuel graphs in the patent below. I forgot the curves are non linear, so an integral or average of the MAP pressure may not be enough. It seems like it would have to be done in real time. The formula should be evaluated at every sample, or maybe every couple of samples depending on the processor.

I'm sure there'll be a thread on it at some point.

I was talking with Fred about this earlier and he related that The Volvo was running great with only real time fuel calcs. Which may mean that vaporization calcs are less important. But I'm thinking it could also mean that he nailed a good moment to sample MAP for that motor.

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

Post by Fred »

MotoFab wrote:I was talking with Fred about this earlier and he related that The Volvo was running great with only real time fuel calcs. Which may mean that vaporization calcs are less important. But I'm thinking it could also mean that he nailed a good moment to sample MAP for that motor.
Timing the MAP readings gets you low noise in your readings. The specific timing of the MAP readings could get you bettter dynamic range, if you get a minimum pressure reading. But provided they are timed at all, relative to the vacuum wave in the manifold, you should be able to get a consistent result. Hitting the sweet spot for MAP reading timings for your purposes could/will make a difference, but I can't see it helping when you're just tuning based on the reading and not doing WW stuff. The volvo was a great proof of concept, but not much more really :-)

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

Post by MotoFab »

It's cool that The Volvo ran so well with just immediate, just prior to injection, fuel calcs.

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

Post by Fred »

MotoFab wrote:It's cool that The Volvo ran so well with just immediate, just prior to injection, fuel calcs.
Just to be clear, not just no WW code/no XTau/no EAE, also no transient response corrections at all, no accel pump, no AE at all :-) I thought it was cool, but I also recognise that it's a benign vehicle to base an opinion on. We'll see how well it works on my ute with a huge throttle on a small engine :-) Time will tell!

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

Post by obi-lan »

Just wild idea... Would cold enrichment at idle work at loop where PW would be adjusted based on wideband lambda reading?

When I was first time fidling with MS somebody told me that just adjust WUE so that lambda shows 14.7 all the time and you'll be fine. And I've been fine with that, my VW G60 engine idles smooth atleast from ~0C.
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Re: Warm Up Enrichment - how much do you run at what temps?

Post by johntramp »

I think WBO2 sensors can be inaccurate at idle.
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Re: Warm Up Enrichment - how much do you run at what temps?

Post by jharvey »

They are especially inaccurate when cold. The sensor will likely heat up faster than the engine, but will be inaccurate for much of the time the engine is cold. When the sensor is cold, it will be best to run in an open loop.
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Re: Warm Up Enrichment - how much do you run at what temps?

Post by Fred »

As Jared said, open loop is the only way to go under certain circumstances, warm up being one of them.
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