Need help understanding ASE taper

Tuning concepts, methods, tips etc.

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Targa44
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Need help understanding ASE taper

Post by Targa44 »

In looking at the starting sequence, we have:
1 - Priming pulse

2 - Cranking PW table (up to 300 rpm for me)

3a - ASE /
3b - ASE taper / all incorporated with the main fuel table
3c - WUE /

4 - ASE "tapers off" leaving WUE w/main fuel table

5 - WUE terminates at selected coolant temp.

Q1. The default values (MS3) show ASE ending at 180 degrees and WUE ending at 160 degrees. I thought the ASE ended first? Easy enough to change, but I'm wondering why are defaults that way?

Q2. I can't figure out what the table is telling me for ASE Taper. Are the taper "cycles" actually ending the process earlier than the ASE table shows?

Q3. What do the "cycles" represent?.... a large number when coldest. The tool tip says it's "how long" to apply ASE. How does "how long" get measured when the table shows it going to a certain coolant temp at the lowest?

thanks for helping me understand,

kj
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Re: Need help understanding ASE taper

Post by jsmcortina »

Warmup enrichment is a fixed fuel multiplier percentage based on coolant temperature.

ASE is an enrichment adder percentage that applies and tapers to zeros right after startup.
The ASE percentage curve shows the maximum adder.
The ASE taper shows how long (in engine cycles or time) before this tapers to zero.

e.g. say I start the engine to 10C.
My settings:
WUE multipler: 155%
ASE adder: 45%
ASE taper: 350

Internal engine cycle counter = 0
Resultant ASE = 45%

The total enrichment from these factors is 155+45 = 200%.

During the first seconds of running the engine cycle counter counts up, say to 175. The engine has warmed up to 15C
Now, from my settings:
WUE multipler: 152%

The ASE is halfway through the taper, so ASE = 22%
The total enrichment from these factors is 152+22 = 174%.

Now, the engine cycle counter has counted up to 350. The engine has warmed up to 20C
Now, from my settings:
WUE multipler: 150%

The ASE is complete, so ASE = 0%
The total enrichment from these factors is 150+0 = 150%.

On my engine I have found that using a fairly long ASE time helped eliminate a recurring start then stall situation. It is likely due to the extra fuel required while the engine internals are really cold. After a few cycles, even with low coolant temperature, the spark plug, valves and piston crown will start to see some heat.

Hope that helps

James
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Dennis930
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Re: Need help understanding ASE taper

Post by Dennis930 »

kj,

Depending on where you have your CLT sensor is located on the engine will determine what temperature WUE will go to 0%. I my case I use 120* because my sensor reads 130* - 140* when the engine is warmed up in cooler conditions, and CLT reads higher when it is hot outside because these are air cooled engines. I have NTC thermistor mounted on the cam tower for cylinder #3. I hope you are not using oil temperature because it takes a long time to warm up 12 QT's of oil.

For ASE taper, you can change the # of cycles axis to 0.1 sec increments if you are more comfortable with time based taper verses engine cycles (which depends on how many RPM's the engine is turning). If you change to 0.1 sec increments be aware that the label of the table axis does change to seconds. You may find as I did that you may have more ASE taper time at higher engine temperatures to help with heat soak issues when starting the engine hot after sitting for awhile. When the engine is hot, WUE is 0%, but ASE and ASE taper still apply for hot starts.
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Targa44
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Re: Need help understanding ASE taper

Post by Targa44 »

I think I have it conceptually (I've actually made hard copy ring binders for 2 of the 3 large manuals) , but adding in the numbers helps quantify and reinforce.

Here's where I still may be off... a cycle is 1 rev? If I idle at 950 rpm and set the cycle counter to 350 at 10 degrees (default table), I'd only have ~20 sec. of ASE. Seems pretty short.

Q. Is it, rather, additive? i.e. all the cycles at the different CLT temps from 10 up to 180 degrees which would total 2570 cycles or about 2.5 minutes for ASE? (or, cycles start at current temp, then adds up). HOLD THE PHONE - just reread James explanation.... if I'm starting out at 10 degrees, I get 350 cycles, If here in never ending sunshine (California), I start at 50 degrees, I'll get 310 cycles (back to default chart). So, ASE is pretty short.

James - thanks for the comment about extending ASE and extra fuel - you also mention in the manual if it starts and stalls in a few seconds, you need to adjust ASE.

Dennis - CLT is also at #3, but I don't know what type... flat connector. My sensor runs up to 170-180 range when hot. After doing 2 warm-ups with the analyzer, it levels the WUE to the required 100 at 80*. I fished for the "time based" ASE taper mechanism but didn't find it - I'm okay with cycles and that formula for now. Thanks for the tip/reminder about ASE applying anytime for start up.

Again, thank you both for spending the time to help me flog through this.

kj
Dennis930
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Re: Need help understanding ASE taper

Post by Dennis930 »

kj,

To change the ASE taper units from cycles to 0.1 sec, go into the Cranking/Startup dialog box. It is the last item in the dialog box.

A cycle is one engine revolution as far as I know.

Say your engine CLT is 40*, then when the engine starts WUE adds say 117% (17%) more fuel. As the engine warms that % lowers as it follows the WUE curve to 100%. For 40*, say ASE is 47%, when the engine starts that much fuel is added initially but the amount tapers down to 0% based on the length of time @40* specified in the ASE taper curve, say 375 engine cycles.

ASE taper is shorter when the engine is cold because WUE % is much higher and ASE provides some extra fuel to ensure the engine continues to run once it first catches. I never had too much problem with the default WUE% and ASE settings for cold starts, I never had a problem with the car not starting before tuning WUE. I think I may have lowered some of the WUE % values to reduce some richness and stopped WUE @120* for my setup. It takes some time to play with these settings because you typically only get one try a day. The reason I changed ASE taper units to 0.1sec was to extend ASE for heat soaked hot starts. I run 90sec of ASE(set to 6%) for 220* and above CLT to allow to intake tract to cool down and stabilize engine idle for summertime hot starts (which can be in the upper 90's here). I may lower the fuel% and time, I need to go back and look at some hot start logs to see if the engine really needs that much fuel and time.
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Re: Need help understanding ASE taper

Post by kjones6039 »

Dennis930 wrote:A cycle is one engine revolution as far as I know.
Actually, on a 4 stroke engine, one engine cycle equals two revolutions of the crankshaft (720 degrees).

On a 2 stroke it is 1 revolution (360 degrees).

Ken
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billr
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Re: Need help understanding ASE taper

Post by billr »

Two crank turns (for a 4-stroke) makes sense, but I kind of thought a "cycle" in this context was an ignition event. It doesn't really matter to me, it is so easy to set it empirically regardless of what a cycle is defined as. However, I'm asking the FW developers to please clarify...

PS: I'm guessing we should be able to tell from a log; looking at the taper time, rpm, and number of cylinders.
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Re: Need help understanding ASE taper

Post by kjones6039 »

billr wrote:but I kind of thought a "cycle" in this context was an ignition event.
Precisely, Bill! One ignition event erery 720 degrees! Witch,of course, equals 2 rotations of the crank.

Ken
1979 Corvette - 383 CID SBC w/ Holley Pro-Jection 900 CFM TBI, 4-85 lb lo-z injectors & Walbro 255 pump
MS2 v3 w/extra 3.4.2 Release
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billr
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Re: Need help understanding ASE taper

Post by billr »

No, I meant every ignition event, so a V-8 would have four "cycles" per crank turn. I'm not saying that is correct (or even makes sense), just what I had in mind. If one of the developers doesn't clarify soon, I'll dig into a log and figure it out.
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Re: Need help understanding ASE taper

Post by kjones6039 »

billr wrote:No, I meant every ignition event, so a V-8 would have four "cycles" per crank turn
Ah, yes. I think I understand your point about the V-8. The complimentary cylinder is firing when the primary cylinder is on the exhaust stroke. That amounts to one ignition event every 360 degrees of crank rotation. But that doesn't change the fact that in any 4 cycle engine, one engine cycle is 720 degrees, regardless of the number of cylinders.

I hope that doesn't sound too argumentative. It was not intended to be! :)

Ken
1979 Corvette - 383 CID SBC w/ Holley Pro-Jection 900 CFM TBI, 4-85 lb lo-z injectors & Walbro 255 pump
MS2 v3 w/extra 3.4.2 Release
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billr
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Re: Need help understanding ASE taper

Post by billr »

I ran it and looked at ASE in a couple of logs. I'm convinced an ASE taper "cycle" is each-and-every spark event, i. e. four taper cycles per crank turn with my 4-stroke 8-cylinder engine. I had to make some crude approximations on rpm, since the taper is right after the engine fires and rpm hasn't stabilized due to IAC changing from cranking steps to WU steps. Also, I didn't do real accurate interpolation for CLT vs. taper cycles. Bottom line, though, is that it calculated out to 4.92 cycles per crank turn in one log; and 3.8 cycles per crank turn in the next. That's close enough to 4 for me, since the alternative interpretation of cycles would be only 1/8 of that.

My ASE is all over in a second or two, so not really something I fuss about.
Targa44
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Re: Need help understanding ASE taper

Post by Targa44 »

Hey.... ASE works. I still need to tweek, but it fired up the first time. And, that's the first time. Essentially, I added approx. 20% over the default range and added a bunch more cycles to the taper. Haven't tried it when it's hot - maybe another story.

So, thanks one and all. It's been fun listening to the nitty gritty. Now I still need to nail the idle. It wanders almost 100 rpm occasionally while I keep the surrounding cells of Ign., VE and AFR the same.

kj
Targa44
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ASE taper as time based...

Post by Targa44 »

Looking for confirmation.

If I switch to time based vs. cycles, what is the method used in MS? (not how to switch, but what does MS do?)

Q - Does time based ignore the CLT axis and just start the clock whenever the car is started?

Q - With the cycles method using CLT, it's possible to be outside the ASE range? (when hot)

I've let this project sit for another 2 weeks without attention and I've developed some more brain flash rust.

thanks,

kj
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Re: ASE taper as time based...

Post by jsmcortina »

Targa44 wrote:Q - Does time based ignore the CLT axis and just start the clock whenever the car is started?
No.
Q - With the cycles method using CLT, it's possible to be outside the ASE range? (when hot)
Both methods use CLT.

James
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Dennis930
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Re: Need help understanding ASE taper

Post by Dennis930 »

kj,

When the engine is cold you will have both ASE and WUE. For an air cooled motor, WUE enrichment needs to end by what ever CLT you see (in logs or in TS) when the engine is warmed up when driving in cold weather. CLT will change depending on what engine RPM is occurring, so when it is cold WUE needs to stop by whatever the lowest CLT is occurring otherwise you will be running around with WUE happening when it should not.

For hot starts you will not have WUE because the CLT cutoff will have been exceeded. But you can still have ASE because the ASE% table can extend to a higher CLT than WUE to aid in hot starts. I run more ASE taper time or cycles at higher CLT to aid in hot start heat soak issues, but at those higher temperatures ASE% is only 4% for my tune.
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Targa44
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Re: Need help understanding ASE taper

Post by Targa44 »

Thank you --- as soon as my head hit the pillow last night and I was still thinking about it, it occurred to me. I could run the ASE graph out to 300* and whatever % adder I wanted, but the amount of ASE will only be for what's in the table - either via cycles or time allotted where ever the CLT points are plotted.

...talk about over thinking this stuff

thanks,

kj
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Re: Need help understanding ASE taper

Post by Djovani_jr »

Why do ASE and WUE act simultaneously?

It would be logical to turn on the ASE after the engine start, then WUE

If they are active at the same time, is it possible to completely disable ASE by adding to WUE?
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Matt Cramer
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Re: Need help understanding ASE taper

Post by Matt Cramer »

Djovani_jr wrote:Why do ASE and WUE act simultaneously?

It would be logical to turn on the ASE after the engine start, then WUE

If they are active at the same time, is it possible to completely disable ASE by adding to WUE?
ASE is an adder applied to WUE. To disable ASE, just set it to zero.
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Re: Need help understanding ASE taper

Post by Djovani_jr »

Matt Cramer wrote:
Djovani_jr wrote:Why do ASE and WUE act simultaneously?

It would be logical to turn on the ASE after the engine start, then WUE

If they are active at the same time, is it possible to completely disable ASE by adding to WUE?
ASE is an adder applied to WUE. To disable ASE, just set it to zero.
Will it work if ASE disable and add a litle to WUE or I will have problems after start?
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Re: Need help understanding ASE taper

Post by Matt Cramer »

It probably won't start as well as it would using ASE. What exactly are you trying to accomplish? Is there a specific issue you're trying to fix?
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