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Old 09-15-2022, 01:28 AM   #11 (permalink)
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Originally Posted by EcoCivic View Post
Awesome, thank you so much! I'll try those and see how they work for me. I have a very similar setup- JDM K24A, USDM 06 TSX cams, RSX oil pump, OEM oil cooler, Accord cable throttle body, custom cold air intake, and stock header for now although I will eventually need to change that because the collector is directly above the back of the subframe and it would be impossible to get an exhaust on it. I'll probably get a long tube 4-2-1 header eventually since it should be best for fuel efficiency and overall torque. Out of curiosity, how did you tune yours? Did you street tune it or was it dyno tuned?

Yeah my base RSX transmission's 5th gear is definitely shorter than ideal considering the torque of the K24. I think the ideal transmission for my setup would be an 02-04 RSX-S 6 speed with 04-08 TSX 5th gear, 9th gen Si 6th gear, 4.0 final drive, and OEM LSD. I'm sure the 3.4 final drive works great in an Insight, but I think it would be a bit too tall for my heavier Civic.
This is it in the Insight and the 3.4:



I imagine you're right. Higher weight, larger tire size, 4.0 ought to be just about right.

I got an MBT timing map from Jeff Evans and did the rest of the tuning myself. It was hundreds of hours of logging. I mapped out best power by tuning all of the fuel maps to within ~1-2% for every VTC angle in every cell, then graphing them all. You can check out my K swap thread for details. It was never dyno'd.

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Old 09-15-2022, 06:48 AM   #12 (permalink)
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Hmmm...there definitely is a speed below which you could accumulate some bearing wear every time the throttle is tapped to raise the engine speed. I doubt it's above 500rpm though, because engines have some lugging resistance designed in, and most engines can be run at full throttle at 1500rpm or lower. I would turn down the idle speed until one of the following happens:

1. Fuel usage stops going down despite decreased speed (unstable combustion)
2. Not enough electrical power generated to at least provide some charging for the battery
3. Engine sputters on transient load instead of quickly revving up.

Pretty much every modern car is able to idle at 650 and most "normal" 4 cylinder cars can idle at 600 if you ask them to.

Timing wise, I think the principle of operation should be "perfect is the enemy of good enough" (you can be off by a degree or two, maybe more, and not have noticeably less power), and extrapolate as much as you can based on maps you can find from other engines, and use reaction rate chemistry from high school to help you extrapolate based on load, temperature, lambda, etc.

Last edited by serialk11r; 09-15-2022 at 06:54 AM..
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Old 09-16-2022, 07:38 PM   #13 (permalink)
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Thanks for the responses everyone, it sounds like slightly lowering the idle shouldn't be a problem. I did notice that the coolant now seems to run slightly warmer after idling for a couple minutes, presumably due to the lower flow rate since it quickly cools off with slightly higher RPM. The difference doesn't seem anywhere near large enough to be problematic, but it's definitely something to keep an eye on if you lower your idle speed. I suspect heater performance at idle may be somewhat worse too since coolant flow seems to have been affected, but it's been too hot to test that.

I'd like to try to find a way to lower the cold idle RPM too. Even starting at 80+ degrees it initially revs to nearly 2K RPM which seems unnecessary. Since I live in Tennessee and use a block heater, it hardly ever sees cold starts below around 60 degrees. I haven't found any way to change the cold idle in Kpro, so I'm thinking of eventually installing some kind of plate between the throttle body and the IACV with a hole only large enough to allow for something like a 1200 RPM idle. Not sure how well this would work in practice, but I think it's worth a try.
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Old 09-16-2022, 07:49 PM   #14 (permalink)
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Thanks for the responses everyone, it sounds like slightly lowering the idle shouldn't be a problem. I did notice that the coolant now seems to run slightly warmer after idling for a couple minutes, presumably due to the lower flow rate since it quickly cools off with slightly higher RPM. The difference doesn't seem anywhere near large enough to be problematic, but it's definitely something to keep an eye on if you lower your idle speed. I suspect heater performance at idle may be somewhat worse too since coolant flow seems to have been affected, but it's been too hot to test that.

I'd like to try to find a way to lower the cold idle RPM too. Even starting at 80+ degrees it initially revs to nearly 2K RPM which seems unnecessary. Since I live in Tennessee and use a block heater, it hardly ever sees cold starts below around 60 degrees. I haven't found any way to change the cold idle in Kpro, so I'm thinking of eventually installing some kind of plate between the throttle body and the IACV with a hole only large enough to allow for something like a 1200 RPM idle. Not sure how well this would work in practice, but I think it's worth a try.

What you're looking for is the "IACV duty cycle" slider. It affects the IACV for both hot and cold idle, but you can partially compensate for hot idle with ignition timing.
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Old 09-16-2022, 08:30 PM   #15 (permalink)
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Quote:
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What you're looking for is the "IACV duty cycle" slider. It affects the IACV for both hot and cold idle, but you can partially compensate for hot idle with ignition timing.
Thanks. I saw that, but I didn't try adjusting it yet. I didn't realize it actually changed the idle RPM setpoint. The cold idle will certainly take a lot of trial and error to get right since I don't have much time for adjustments for obvious reasons.
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Old 09-17-2022, 01:32 AM   #16 (permalink)
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Thanks. I saw that, but I didn't try adjusting it yet. I didn't realize it actually changed the idle RPM setpoint. The cold idle will certainly take a lot of trial and error to get right since I don't have much time for adjustments for obvious reasons.
I don't think it actually changes the idle setpoint per se, but it holds the idle up. If you raise it, both cold and hot idle rise, and if you lower it, hot idle still aims for the target idle, while cold idle drops. Lower it too far and it will have a harder time hitting hot idle, and/or it may be easier to stall, because there's less ignition advance in reserve to control idle with.
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Old 09-17-2022, 02:39 PM   #17 (permalink)
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The most efficient idle speed is 0rpm.
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Old 09-22-2022, 05:13 PM   #18 (permalink)
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The most efficient idle speed is 0rpm.
Agreed, but killing the engine just isn't always possible/practical.
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Old 10-13-2022, 05:11 PM   #19 (permalink)
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Quote:
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Here is a link to my repository of tunes:

https://drive.google.com/file/d/13Dz...ew?usp=sharing

The motor was a K24A with the 04-05 intake, Accord cable throttle body, stock header, 2.5" exhaust, RSX oil pump, and 06-08 TSX cams. I had a 50° VTC with a 40° limiting pin, but it should work fine even if you have only a 25°.

The only thing I'd caution is to listen for knock, as the tunes were very much maximizing ignition advance for each octane level - the 93 tune is essentially MBT everywhere but at WOT below ~2250rpm, where I still had to pull some advance. You can, of course, simply flash a 91 tune if you're running 93 and still getting knock on the 93 tune, but I'd be happy to help adjust the ignition tables to fix that.

There are lean burn and non-lean burn variants for each fuel grade. You'll want to tick or untick the boxes based on what sensors you have - mine was complete, with upstream and downstream O2 sensors and full emissions set up. You'll also want to adjust the transmission ratio table.

42mpg is great. I found gearing was absolutely key, and gained another 5+ mpg when I got my 3.4 final drive and 9th gen 6th installed.
Just loaded your 93 octane non lean burn tune and for some reason it doesn't work at all with my K24. The idle is really rough and lopey when cold, it refuses to idle when warm, doesn't want to restart when it dies out, and generally ran bad enough that I had to pull over and reload the base map. It seemed to possibly be running rich, I got a lot of white/grey smoke and it was somewhat hard to start when I reloaded the base map like it was flooded.

I'm still confused by why your tune wouldn't work for my engine since I have an almost identical setup. The only thing I can think of is maybe your fuel pressure was way different than mine. What fuel system do you have and what fuel pressure are you running?
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Old 10-13-2022, 05:25 PM   #20 (permalink)
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Just loaded your 93 octane non lean burn tune and for some reason it doesn't work at all with my K24. The idle is really rough and lopey when cold, it refuses to idle when warm, doesn't want to restart when it dies out, and generally ran bad enough that I had to pull over and reload the base map. It seemed to possibly be running rich, I got a lot of white/grey smoke and it was somewhat hard to start when I reloaded the base map like it was flooded.

I'm still confused by why your tune wouldn't work for my engine since I have an almost identical setup. The only thing I can think of is maybe your fuel pressure was way different than mine. What fuel system do you have and what fuel pressure are you running?
Fuel pressure is a good bet. It's tuned for around 50psi. If you wanted to do a 5-10 minute drive with logging running and send it to me, I'd be happy to push some tweaks and we can see how it does.

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