Hondata

KManager 4.1.4.0
PRB ECU
K24/K20 swapped 2004 S2000
Magnus Sheet Metal K-Series Intake Manifold
80mm KTuned TB (no idle control valve)
KTuned FPR
Injector Dynamics 725
E85 fuel

Hello,

Sorry for this lengthy post, but I wanted to add as much info about my issue and what I've tried.

Recently I swapped my 90mm TB for an 80mm and I've been having issues with my idle and setting my TPS WOT.

My idle issue is that it won't drop down to what I have it set at (1000) when coming to a stop and TPS showing it's at 0% Instead it hovers around 1350 and does not retard/adjust the timing like it does when it idles properly. It idles fine if I first start the car. Also if I blip the clutch when at a stop to bring the RPMs down, it will start idling correctly. Setting my ignition timing to around 5 in columns 1-3 and up to 1500 RPM allows it to go into idling mode, but I get serious hesitation when taking off from a stop.

I'm using the same TPS and made sure to follow all the proper procedures to calibrate it. I set the TPS min/max to default, uploaded it to KPro, adjusted the TPS to as close to 0% as I could get it, read in the new min/max from the ECU, and re-uploaded it to KPro. From the datalogs, the TPS values show correctly. 0% at throttle closed and 100% all the way open. I've tried physically re-positioning the TPS in a variety of positions and re-calibrating. I've also tried setting the min TPS calibration value to 5% so the ECU would see it as a negative value. Both did not change the behavior of either of these issues. I saw this issue before with my 90mm TB, but I was able to adjust it's idle screw low enough so that it didn't have the airflow to get up to anything past 1000 RPM.

Maybe I'm not understanding all the conditions required to go into idle mode, but I would think with the TPS at 0% and VSS at 0, that the idle ignition control would take over.

My second issue, which may or may not be related, is Kpro not following what I have set in TPS WOT. These settings did work before with my 90mm TB and were even lower than my attached calibration. In the datalog attached you will see that with just 1% throttle, it goes in to WOT mode. Even though I have 10% and higher set in the tables.

The reason I think these might be related is because it seems like the ECU thinks my TPS value is higher than what KPro is showing.

Without an idle control value the ECU has little control over the idle speed. I'd guess that the throttle body is leaking a lot around the throttle plate. The best cause you are going to get without an idle valve is a low cold idle and ok hot idle, or an ok cold idle and a high hot idle.
The ECU will not use ignition controlled idle because the engine speed (1300 rpm) is higher than the idle speed (1000 rpm).
The open loop behavior is odd, but your TPS tables are very low (10%). I'd put them back to stock values (50-80%). The
Also your injector dead times are low, and you should disable the acceleration smoothing retard.

Thank you for taking time to look at this for me.

Regarding my idle issue, what you posted makes sense. Being that the RSX ECU was designed to use the IACV to control the idle and making large RPM adjustments (1300 to 1000) was probably not the job of the idle ignition control.

I've been getting some hesitation and a lean spike during fast tip in, so that's why I've been playing with the TPS WOT settings. How much of the lean spike is due to my large TB / large volume intake manifold or my tune, I don't know. The lower values did work before. I'll be swapping back to my 90mm TB and will use the calibration when it did work to see if that changes things. Could my injector dead times cause a lean condition on tip in?

Thank you also for checking my injector dead times. Right now I have my fuel pressure set to 43.5 psi. I pulled the numbers you see in my calibration from the Injector Dynamics site.

From ID website
43.5 psi
8v - 1975
10v - 1355
12v - 1040
14v - 795
16v - 730
cc/min - 715

Looked around and seems most are setting their fuel pressure to 50-60. Haven't tried a higher pressure yet. Is this suggested? I've read on these forums that dead times should be reduced if AF goes rich during fuel cut, which I do get between shifts or whenever the MAP pressure drops fast.

Real quick, is it normal for the battery voltage to jump between 14v and 12v during a drive? Seems to stay at 14v when the engine is cold and at high speeds. Then jumps between 14v to 12v based on load and if the fans are on.

Apparently the jumping between 12v and 14v is factory behavior from Honda when the ALTC wire is connected. Supposedly it saves fuel.

The K-Series ECUs do not implement the 12.5V fuel saving mode. This is some other problem, especially if it changes when the cooling fans come on.

ID dead times should be around 1.1ms @ 14V. The figures on the website are too low.

The K-Series ECUs do not implement the 12.5V fuel saving mode. This is some other problem, especially if it changes when the cooling fans come on.

My ECU does seem to be doing this. I've found a few write-ups on the net that detail how it works and my 12.5v drop pretty much follows this logic.

Alternator low output mode activates when these conditions are met
-Engine coolant temp above 177 F
-Electrical load below 15 amps
-Vehicle speed between 10mph and 50mph or at idle
-During fuel cut
-Engine speed drops below 3000 RPM
-Deactivates when engine speed exceeds 3600

There are delays and other logic that seem to keep it from bouncing around. With my fans on, it drew my ELD amps above 15. So that explains what I initially saw in my logs.

ID dead times should be around 1.1ms @ 14V. The figures on the website are too low.

Thanks, I'll give that a try. Looks that's for 60psi, which I will be also trying. From searching your forums, it looks like it's a general rule to use the ID's dead times for 10 psi higher. Wondering if hooking up a vacuum line from my FPR to intake manifold would smooth this out...