Cold start fuel changes to fueling map?

[Audiomaker]

Hi everyone,

Sorry for what is sure to be a redundant post, but I really couldn't figure out the keywords to search for this answer.

What I'm wondering is...

I have heard that the ECU makes changes to the fueling when the motor is cold.

I run a PCIII and it of course has it's own map. The PCIII map does not have a "cold" map, just a single map.

So what is happening when the bike is cold? Is the ECU providing it's own map until warm, or... is it modifying the PCIII map by adding more fuel by percentage?

Or ? Or ?

I'm on a Gen1 turbo. There's no O2 sensor, but the bike seems like it does some kind of fueling change when the engine gets to about half of normal operating temp'.

Please clue me in on what happens.

Many Thanks
Sean

 

[kromdom]

not a techie but on both my bikes (which both have PC Vs with maps on it): I hit starter the button and I let the bike do its thing. While idling, I gear up and by the time I am done, the bike has reached its operating temp and I go. I do hear the revs start "high" and then it drops when op temp is reached...so I am guessing the ECU is doing its thing.

P.S. On my truck (supercharged, dyno'd/tuned using a handheld tuner), same thing happens: fire up (rpms go UP) and then after 1-2 minutes, rpms go down. In both cases, I doubt the ECU is using a "cold map" but engine is merely getting up to operating temps. Back to my earlier disclaimer: I am a "plastic" mechanic

 

[Audiomaker]

not a techie but on both my bikes (which both have PC Vs with maps on it): I hit starter the button and I let the bike do its thing. While idling, I gear up and by the time I am done, the bike has reached its operating temp and I go. I do hear the revs start "high" and then it drops when op temp is reached...so I am guessing the ECU is doing its thing.

P.S. On my truck (supercharged, dyno'd/tuned using a handheld tuner), same thing happens: fire up (rpms go UP) and then after 1-2 minutes, rpms go down. In both cases, I doubt the ECU is using a "cold map" but engine is merely getting up to operating temps. Back to my earlier disclaimer: I am a "plastic" mechanic

Yeah, I'm trying to figure out what "it's thing" actually is :-)

I feel a hard step between cool and warm... almost like a completely different map was loaded.... i.e., like it doesn't change with temperature, but at temperature. This doesn't happen at operating temp, it happens about half way.

It also feels like it is air/fuel related... like a choke, more than fast idle. My idle speed doesn't really change much.

The ECUeditor types probably know the answer to what the bike is programmed to do and when?

Sean

 

[dadofthree]

Send Frank at powerhouse a PM with your question.

We have many mechanics and tuners on the site, hopefully someone will speak up to answer your question.

 

[BoostCreep]

I can't speak directly for the Hayabusa ECU but here's how it works for almost every stand alone and ECUs I've worked with.

You don't have a second fuel map for the cold start, what the ECU does is it monitors the coolant temperature and on that alone it will add a % of fuel to your overall map until you hit a point. So say Suzuki said when the engine coolant is at 80 degrees, we will add 10% more fuel throughout the whole map, then at 100 degrees we will add 6% fuel to the entire map, when you hit 150+ degrees you add 0% fuel to the whole map (running off just the regular programmed fuel variables). Just an example. In the ECU this is typically called something along the lines of warmup enrichment; depending on the company, the programmers who designed the ECU or the people who tuned it, it will be called different things, have different (more or less) variables, and so forth.

You go on and there will be something similar to air intake temp sensors; so on and so forth. Then you have accel enrichments (similar to an accelerator pump on a carb), you can have two different fuel and timing maps for Nitrous if you want, ECUs are pretty fun.

 

[Audiomaker]

I can't speak directly for the Hayabusa ECU but here's how it works for almost every stand alone and ECUs I've worked with.

You don't have a second fuel map for the cold start, what the ECU does is it monitors the coolant temperature and on that alone it will add a % of fuel to your overall map until you hit a point. So say Suzuki said when the engine coolant is at 80 degrees, we will add 10% more fuel throughout the whole map, then at 100 degrees we will add 6% fuel to the entire map, when you hit 150+ degrees you add 0% fuel to the whole map (running off just the regular programmed fuel variables). Just an example. In the ECU this is typically called something along the lines of warmup enrichment; depending on the company, the programmers who designed the ECU or the people who tuned it, it will be called different things, have different (more or less) variables, and so forth.

You go on and there will be something similar to air intake temp sensors; so on and so forth. Then you have accel enrichments (similar to an accelerator pump on a carb), you can have two different fuel and timing maps for Nitrous if you want, ECUs are pretty fun.

That makes total sense, but on my bike it feels like 2, or 3 at the most stages.

Like the first stage is cool... it's adding fuel, then the second stage is normal (PCIII map only), then a hot stage. That however is just the way it feels, I have no evidence of that.

It also makes sense that the fuel adjustments would be on a percentage basis compared to the PCIII map, except that the PCIII is an external piece of hardware and I don't know how the ECU deals with that.

While I'm sure there are many tuning anomalies that could be associated with the "warm up enrichment", mine is such that the bike runs great when cold... or that is to say, it runs great as a bike that's cold should, then once it hits maybe 100 degrees, something instantly changes and the bike runs well but surges at idle through about 2000rpm. The change happens suddenly and more or less predictably... like someone flipped a switch.

Let me put that another way... The bike idles and runs fine when it's cold. It runs stronger (i.e. it's faster) warm, but surges at idle and sometimes even dies sitting at a light. It really feels AFR related and that could be leaking vacuum, but I haven't found any disconnected or leaking vacuum lines. So air leak or map? Hmmm?

Knowing what changes the ECU is making to the AFR during this warmup might help someone understand which way the map needs to go, or if it could be the map at all.

For instance... is the ECU adding a percentage of fuel at all RPM's when cold, or just the low range?

If one tunes when warm, then does this additional fuel foul the plugs if you do a lot of stop and go in-town runs where the bike doesn't fully warm up?

If you have a good (tuned at operating temp) PCIII map, would you then want ECUeditor to make adjustments for less enrichment if you're doing a lot of short/cool trips to the corner store?

(sigh)
Sean