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Cold Start and ASE and driving off

 
Old 03-14-2019, 07:17 PM
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Default Cold Start and ASE and driving off

I'll probably change this at some point, but currently the car is targeting an idle of 13.5AFR when warm to get MAP in the lower 30s. I've adjusted ASE and WUE accordingly to keep it approximately there during the entire warmup. All that in mind, is what I'm experiencing normal? Essentially, I can't turn on my car and just drive off. I have to wait until ASE is essentially done.

When I played with some tuning that made my take-offs feel nicer, it essentially recommended lots of fuel to compensate the sudden lean situation during taking off the line (dropping the clutch and opening throttle). But when ASE is active this ends up being LOTS of fuel. What I'm experiencing is that if I turn on the car and try to drive off within the first second or two, the car essentially dies. If I wait about 15-20 seconds or so, I can take off more normally, but it still feels slightly sluggish. Does it make sense that this bandaid approach is what's causing my issue?

Also if you look at the datalog, I keep on seeing this "feature." After startup, the AFR is pegged at ~14.6, makes its way down to almost full rich, then spikes to full lean then back down to what I assume is finally the "real" AFR. Is this just the sensor warming up? I also realize I need to change the RPM columns slightly to trap the idling. Adding the 42 kPa row has helped out immensely in trapping the idle downward since the transitions upward need more fuel usually. Thanks!
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Old 03-15-2019, 12:58 AM
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ASE is intended for seconds after starting - no longer. For the warmup, use WUE only.

To log AFR during starting, you want your key in the ON position for about 20 seconds before cranking so the wideband can heat up.
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Old 03-15-2019, 01:20 AM
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Correct. So, for whatever reason if I literally wanted to start the car and then drive within a few seconds (<5 seconds), I need to shorten the duration of ASE it seems. With this datalog, ASE taper is ~14 seconds. Is that too long? And does it make sense to typically avoid actually driving the car until ASE is "done?"

And noted on the WB heating up. I'll do that tomorrow AM.
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Old 03-15-2019, 05:46 AM
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I never drive any car that hasn't warmed up at least two minutes if fully cold. I'm usually looking for the coolant gauge to begin to rise prior to moving. And I never boost until it is FULLY warmed up.

Wear is dramatically higher when engines are below operating temperature. There's a chart around here somewhere.

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Old 03-15-2019, 12:47 PM
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Huh. I've never seen that chart. This even includes low load driving off, etc? Or is it strictly performance driving? I see though, 1mil ~140F, 2mil ~100F, and 3mil ~80F.

Good to know though. Thanks for that.
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Old 03-15-2019, 01:21 PM
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I always thought the wear was associated with the dry-start, when all of your oil has drained down into the pan. Hence things like Accusump oil accumulators.
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Old 03-15-2019, 02:59 PM
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[QUOTE=sixshooter;1526746]I never drive any car that hasn't warmed up at least two minutes if fully cold. I'm usually looking for the coolant gauge to begin to rise prior to moving. And I never boost until it is FULLY warmed up.

Wear is dramatically higher when engines are below operating temperature. There's a chart around here somewhere.

This agrees exactly with my Lotus Elise ECU not permitting big cam engagement until the coolant temps hit 160. I, and others in the Lotus community drive about 20 min. before putting my foot into the throttle, as it takes that long for the oil temp to be optimal, even tho the coolant is at an OK temp within 4-5 min. Your engine guts will thanks you!
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Old 03-15-2019, 03:47 PM
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I mean, to clarify - when I say drive off, I just mean driving off to commute. Are you (sixshooter) saying that you warm up the car for a full 2 minutes before even driving the car at all? Just wanted to clarify.
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Old 03-15-2019, 05:09 PM
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I always properly warm up a vehicle before moving it at all when it is stone-cold. There's nothing outside of a real emergency that can't wait for the needle to climb up off of the C. And I never ever boost or rev the engine really fast until the oil is up to full operating temperature.
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Old 03-15-2019, 05:44 PM
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OP: yes, this is a typical phenomenon. I think it has to do with cold intake and valves. The car will react differently between driving off at CLT = 60F (A) 2 seconds after starting vs (B) 2 min after starting (if you had started at, say, 45F). CLT temp the same, but during vs well after ASE is doing anything at idle.

Six: I was intrigued at how one might hold an engine at 45F to accumulate 50 hours of run time. I’m this video, there is a description of a Toyota engine with special cooling (though at 70F) looking for increased wear. This video may also be germane to the oil life discussion in the Catch Can thread:
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Old 03-15-2019, 05:47 PM
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If a testing facility has a large reservoir of appropriately chilled water it wouldn't be much problem at all.
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Old 03-15-2019, 05:51 PM
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Also, through lots of temp correction to my EAE Added to Wall, I can get away with start and drive, but then stopped doing it and opt for letting the engine warm up some, for reasons given above. Six, I like the idea of waiting for gauge to move.

I have my Rev Limit curve set to keep below 4K until 175F. Not quite as good as oil temp gauge, but an Approximation.
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Old 03-15-2019, 06:11 PM
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Interesting indeed. Bummed to really only learn of this now. Learning's learning. As far as the odd quirks driving off right off of cold (in this case sitting for >10 hours, ~70F) - I was more wondering if I had issues in my tune since the oem ecu doesn't necessarily have these quirks. It is interesting when it's ~40F outside, I have a more natural tendency to let the car warm up a bit before heading out.
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Old 03-15-2019, 08:00 PM
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A bit more research and I’m gonna waffle back to waiting 20 -30 seconds and driving. Results in less time with engine cold (high wear territory) and less time with enriched mixture washing cylinder walls.

In in other words, the graph Six showed is actually a call to get the engine parts warmer faster, and not hang at those low temp, high wear conditions.

Have also realized that my Expedition would take like a hour to warm up just idling. (Anecdotal by memory).
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Old 03-16-2019, 07:29 AM
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The trade off is free idling with no load versus loading the engine and increasing the cylinder pressure and ring wear when the pistons are loose in their bores. When the pistons are cooler and smaller they rock and scuff the skirts and wear the bores laterally more easily. There's a reason engines are noisy when first warming up.

It is good to not take my word for it and do your own research and formulate your own plans.

What you saw is definitely a great reason to always use a thermostat and not just a restrictor like some people advocate.

Data point of one so grain of salt- my Tundra was always warmed up prior to departure every morning. It had 460k+ miles and didn't burn any oil or have excessive blowby. Rotella T6 was exchanged every 5k miles. I sold it a few months ago and it was running fine.
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Old 03-16-2019, 10:13 AM
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Great video, thanks!
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