Hondata

First let me say I have a good understanding of how to adjust the idle and IACV Duty cycle and did so according to the instructions in help. However, I am of the opinion that the idle drops too fast when the car revs over 2,000rpm and the throttle is released suddenly. When revving under 2,000rpm the idle drops slowly and returns to idle smoothly. When the engine is reved above 2,000rpm (3,000 as an example) the revs starts to drop slowly and then drops rapidly from around 1500rpm as though the ecu is saying "hey the rpm should be 800 by now so let me shut off more air in order to get the revs down to idle. As a result, the revs drop rapidly and the engine "beats down" (goes below the target idle) and then returns to the set idle speed. Can this be corrected? I remember my stock ecu holding the rpm at about 1,000rpm during the above condition and then returning slowly to the target idle. Can hondata get this to happen? I tried to get the revs to return slowly by changing timing and fuel in the 1500rpm range but nothing works. I'm convinced it's just the way the programming is right now. Moving the slider bar all the way to the right doesn't help either. It's a minor problem but it would nice to see it working like stock again.

check overrun cutoff MAP settings

theres a bug in 1.4.2beta(if thats what your using) thats not holding the values when the cal is saved.
check the 8000rpm value has not reverted to a 500rpm value when u upload a cal,it appears the ecu has conflict with 2 500rpm values & doesnt know where to stop the fuel cut.
i seem to be able to clear this condition by changing it back to 8000rpm then upload before save.
ive asked hondata for a fix on this but they seem to have forgotten about it.....

could also be possible that u just need to fine tune the MAP values at lower rpm for your motor,or u have to check your TPS value or throttle cable operation

Thanks for the reply. In order to fine tune the lower rpm maps could you give me a little insight as to what exactly happens when the injectors are cut? Is there a fixed amount of fuel that is injected under this cut condition? Is this fixed value adjustable? Looking at the air/fuel ratio under this condition it goes very lean. Maybe it's too lean hence the late recovery when it returns to idle. If I can adjust the minimum fuel injected maybe that would correct the problem. It's an H22A turbo with 1000cc injectors. Car runs great otherwise. The 8000rpm value is fine. I take it you're talking about the 8000rpm value in fuel cutoff map right? I am using the 1.4.2 beta version. TPS value is set to .9% and 1000ms cuz I wanted to delay the cut as long as possible- seemed to help a little. Calibration attached.

this is what i see when i first open your cal...


what beta version are u using?
im using the one that is posted up right now,are u using the original that was posted,like the 9th june?

see how the 8000rpm value has changed to 500rpm(circled red),check yours again,would be interested to know what u see...

overrun fuel cut is exactly that,the fuel is cut completely 100%,thats why it goes mega lean,will run right off the top of your AF gauge scale.

i only started looking into this when my car started doing similar to yours after using the beta,but stopped looking any further when hondata confirmed a problem with the values & now my car is in pieces so i cant do any further testing obviously,so i'll be of little value to your further understanding of the problem.
didnt think there was much point in confusing myself further when i couldnt even trust the values i was using,but i seemed to have alleviated the condition somewhat by uploading before save as i stated above.
again,i fiddled & tested it for about 5mins,before stripping the car down,so i cant tell u exactly the outcome yet.

it appears to me(from my very limited understanding of this matter) that this conflict of 2x 500rpm values & the motor wont catch on anything till min target idle(or something) takes precedence over the situation & cancels any remaining fuelcut.

if u do see the 2x 500 rpm values,i would prob wait until a fix before tearing your hair out trying to fix it,then at least u can trust the values are correct that your trying to work with.
if u want to fiddle in the meantime,i would prob try to give yourself a fuelcut cancel point at around the 1000-1250rpm mark & below on the MAP scale with like a 25-30kPa value,then see if your moving idle speed will catch & then settle to min stationary idle when stopped.

i'll reitterate,i have very little understanding of this whole process myself & i could have that all arse-about,im just basically thinking out loud here,but hopefully i can bump your own thinking & u can fill me in on what to do when i get my own car back together & can test further.

even better,hopefully someone with some better understanding on the subject chimes in,but i certainly dont envy your task of trying to get 1000cc saturated injectors running smoothly thru this little process.....do u really need all that injector,how much boost u running?

edit:can u get a datalog of the problem so i can see whats happening in your circumstance,im sure hondata are going to ask u to provide a log in any case

I'm using the version that was posted up June 9th I believe. I didn't realise there was a newer version. That 500rpm index circled remains at 8000rpm on my version. No problems there.

Do you think a fuelcut cancel point value would be 25-30Kpa as you say or do you think it should be let's say 10Kpa. My thinking is it would still see a map value below 25-30Kpa and still cut. Whereas if a use a value like 10Kpa it won't see a value below this point and stop the fuelcut. What do you think?

Yes it is good to have these discussions. Gets you thinking. I'll try both settings above and let you know if it helps. The 1000cc injectors idle great otherwise. I run a max of 15psi right now but I'm setup for 30psi otherwise. Will need to change my restrictive log manifold before increasing the boost that's all.

I will get a datalog and post up. I tried increasing the fuel values below 20 inches to try to get it to use more fuel under this condition but the fuelcut values overrides this. Hmmm...... now that I mention that there is another TPS fuel cut that will override the adjustment I'm about to do to the fuel cut map. LOL. :( So maybe this TPS fuel cut needs eliminating all together and let the fuel cut be based on rpm vs. map. I'll try a value of -1 for TPS fuelcut in an attempt to eliminate it. What do you think?

oh ok,30lb h22 sounds like fun,guess your gonna need all the injector u can get lol.

its weird how i can open any old cals created &/or modded pre 1.4.2 & see a 8000rpm value,but anything touched with 1.4.2(including yours) i see a 500rpm value......anyway,your prob best sticking to june 9th which i garbaged unfortunately :(

just reading your posts again,i think ive misread u...
do u mean coasting in an overrun state(ie while driving) to a stop or are u just reving the motor in the garage while stationary & seeing this problem?

if your just reving while stationary,i didnt think there would be any overrun fuel cut(OFC) set without a VSS(higher than some value) input to the ecu,but if u say changing the TPS delay alleviates the prob somewhat,then there must be OFC set.

thats the thing i dont know if i got arseabout or not.
a quick look thru some old data has lead me to believe im wrong about the MAP values effect on OFC that i stated above

my take on the MAP values now is,they have no effect until switching back on the fuel from an OFC state.
ie no fuel will be added until MAP sees a figure above the one set,regardless of throttle input(well maybe to a certain degree of throttle input or something)
eg 2000rpm-20kPa values entered,injectors cut on overrun= no response to throttle input at 2000rpm until MAP reads over 20kPa once again.

i also now think the OFC is set in stone & u wont be able to disable it with the software as is,leaving only the ability to fine tune it.
my OFC seems to disable at a fairly reliable 1050rpm in old data regardless of MAP reading(JDMP72 B18C,yours may differ,like B18CR is about 1300rpm i think).
this is while driving not free reving in the garage btw,which leads me to believe its a fixed rpm trigger that disables it.

i suspect the OFC implementation into the software was a little more complex then first thought,hence the delay on the fix,probably a little more in the code then first perceived.
would have been interesting to know if u had this prob before 1.4.2,but i wouldnt spend too much time on my theories lol,what u describe was just similar to what happened to me while driving,rpm would just keep falling & stick at about 5-600rpm & not lift to idle target again for about 10secs after stopping until i tried uploading the correct 8000rpm value.

Yep. Gonna need those injector eventually.

Cant you go back to the previous version? I still have the downloaded .exe so I can mail it to you. Let me know email address if you need it.

I'm talking about revving in the garage and seeing the problem. Coasting in the overun state is fine in terms of recovery.

Yes I believe fuelcut still is in effect with the car stationary when the map falls below the map at idle. Which is why I believe there is a provision to set the map value with the throttle fully closed under Alpa-N Settings..... So guess what..... I set that to 30Kpa this morning. My car idles at 30Kpa. I don't know why hondata suggested 15Kpa. No car idles there to my knowledge. That's less than 22 inches of vacuum.

The next thing I changed was the the TPS fuel cut. I set that to -1 to eliminate that. It accepted -1. So I was like.........cool.

Now the third thing I changed was the Map fuel cut values. From 500rpm to 2750rpm I set to 10 kpa. My reasoning being it should stop fuelcut at 2750rpm cuz there's no way my engine would see a map value below 10Kpa so it would then use the values in the map tables.

Upload to ecu and guess what. Almost perfect. Rev to 4,000rpm and come back to idle with neglible "stumble" But I like perfection so I still wasn't satified. So I ended up changing the map values below the 30Kpa column (in the map tables) to the same values in the 30Kpa column cuz I figure the engine was still going a little too lean under 30Kpa. Perfect. Perfect Perfect Perfect. Even if I rev to launch control rpm of 5000 it still drops to idle smooth and dont go below 800rpm. There's no more rapid fall in rpm when returning to idle. The Car also drives perfect between gear changes when driving normally. Before I was getting a bit of jerkiness because the rpms were falling too fast. I hope this helps you when you set back up. Let me know. See attached cal.

thanx,i'll keep that .exe in mind if hondata dont come up with a fix before im back on the road,or actually,i wouldnt mind tracking down a 1.4.1 & just putting up with the datalog crap till this is sorted.

the alpha-n settings are only for when using TPS based tables,such as when using itb's,u shouldnt be seeing any effects from changing them values,considering u are still using MAP based tables.
did something change when u changed this value individually or was the change just part of the overall change?

as far as the TPS -1,there seems to be no adverse effects when running of the end of most tables,i see 101% throttle in some of my data(i must be trying to push the thing thru the floor lol),but as far as neg numbers go,wow who knows?
i had my s300 install & tune as part of a deal from hondata backed supplier here in aus,& he had my high speed tables starting at 5000rpm & vtec switching at 4600rpm,took me 3 months to spot the discrepancy but car seemed to have no adverse effects from it,so values must just keep interpolating right off the ends of the tables or something???

for the 10kPa value,im still convinced the value is not in effect until breached from low to high by throttle input,but hey....something has fixed this for u,would definitely be nice if the help file contained something on the workings of this MAP based table,so u knew what u were fiddling with lol.

i think u found the solution in the fueling increase & your probs were just purely based on 1000cc saturated driven accuracy,but again...theories of a total n00b...
will be interesting to see what your AF's are like at idle & if they hold due to closed loop.
what is your O2 setup btw,are u trying to just get some info off the stock O2 or do u have some sort of rescalable inverted linear input to the narrowband input from a wideband?

so did u do all the changes individually or all at once?
would def be interesting to see some data

1.4.1 I have on the CD that came with the computer but getting that to you from Barbados is gonna be tricky lol.

I plan to change the Alpha-N Settings back to 15 but I read where hondata said to increase this setting to 15 (originally 10) if the return to idle was problematic and they weren't referring to ITBs only.

So you're saying you don't think the fuel cut map is in effect until it senses the tps fuel cut is in effect? Interesting if so. So it would means I'm not fuel cutting at all with a -1% in the tps setting. hmmm.... But when I close the throttle suddenly and the map falls below idle map the injector duty cycle goes to 0. It must be cutting. No popping sounds from the exhaust either.

I was thinking so too about the extra fuelling below the idle map range. I got that idea from my brother. He uses 1200cc injectors (yeah...big) in his Peugeot 306 S16 and he says they don't like when he try to go below a certain setting in terms of pulse width. So as a result his car idles slightly rich in order to idle smooth. It's more like a T16 now with 28psi.

The car definitely runs in closed loop at idle. Stoichmeter sweeps. Yea I'm yet to get a wideband. But it was tuned with a wideband. If I turn off closed loop the idle gets crappy.

I did the first set of settings all at once but then I change the fuelling in the tables last. Forgot to take a log.

mmmm barbados ...nice...wish i could pick it up in person lol.

if u look above the alpha-n settings u will see the option to change the fuel/ignition tables from MAP based to TPS based,if u change it to TPS based(which u havent) this should be the only time u'll see any effect from fiddling the alpha-n settings.
what hondata recommended was changing the OFC MAP values down the bottom of the TPS tab to 15kPa(mine are like 22kpa or something in the stock P72 cal,dont know about yours) if hessitation exists.

im just basing my opinion on this recommendation above & a quick look thru some old data as to when these OFC MAPvsRPM values take effect.
i could be way off.

the OFC TPS & OFC MAP are one & the same,ie they are not independant of each other.

using TPS throttle value of 1%/delay 600ms & rpm value of say 1050rpm like i see on my motor as an example for the following,

TPS throttle value=when OFC will occur,ie when ecu sees 1% throttle or less & rpm maintained over 1050rpm, then it switches OFC on,
so u should see INJ dur.=0ms/duty =0%/AF=off the scale lean.

TPS delay=time after ecu sees 1% throttle or less/rpm still over 1050rpm,that it will switch to OFC after 600ms.

OFC MAPvsRPM table=i wouldnt have a fricken clue lol...
what im thinking about this is,

with OFC in effect due to TPS/RPM/delay listed above,
OFC will not be cancelled(ie injectors turned back on),
by a new throttle input(ie trying to get back on the throttle to accelerate again),
until the MAP input received by the ECU is equal to or above the MAP value u have set in the OFC table for any given rpm value.

eg. u lift off throttle at 4000rpm(TPS<1%/rpm>1050rpm),OFC kicks in after 600ms cutting injectors completely,then if u try to get back on the throttle at say 2000rpm,then ecu will not restart injectors until MAP input received by ecu is once again reestablished over say 20kPa(eg of what u mightve set at 2000rpm) due to throttle input from u.

because u say u are still seeing OFC(duty=0%),then yes OFC is still happening. what i was suggesting is just that & a neg value input such as -1% will just be interpreted absolutely by the ecu & u will still get OFC happening because the ecu is just seeing it as +1% anyway.
unless your TPS is not set correctly & u do indeed get a -1% or less TPS value with your foot completely off throttle to cause OFC.
have a look at datalog &/or scale TPS section on TPS tab to see what TPS values the ecu is seeing.
in short I dont think neg values will stop OFC from happening,but if u set your min throttle input value to say 2% that the ecu sees & set your TPS OFC value to 1% then u will stop OFC from happening,
but thats not what u want ideally & im sure there are further implications to ecu never seeing 0% throttle that my OFC twisted brain just cant think of right now lol.....

i forsee this is not over for u yet,due to long term fuel trim,just see how it pans out in the coming km's....oops...i mean miles lol...

god my head hurts now......im going to lie down for a bit.....

Not hurting like mine. LOL.

My thinking is simalr to your in terms of how the entire OFC works. I would say the 2 work together as well. All I would add is that the rpm vs map OFC works conditions must be met as well in order to activate OFC.

That is - u lift off throttle at 4000rpm(TPS<1%/rpm>1050rpm and map below the map value at rpm in the OFC map tables),OFC kicks in after 600ms cutting injectors completely,then if u try to get back on the throttle at say 2000rpm,then ecu will not restart injectors until MAP input received by ecu is once again reestablished over say 20kPa due to throttle input from u.

But what's interesting is this rpm value you're mentioning in the tps OFC. I don't have a rpm setting on my version. R u saying there is a rpm setting in the TPS OFC area? I could see that being an easy solution to my problem. LOL. Cuz it would stop the fuel cut at an rpm below the set point which is what I want. LOL LOL LOL.

EDIT: Oh I understand now that this 1050rpm u're mentioning is only what you've noticed your OFC cancelling at (Not an actual value that can be set). Well mine dont seems to cancel at all until it returns to idle rpm. Not even after increasing the fuel values in the map table showed any signs of returning to the map for fuelling below a certain rpm when OFC is active. I believe I can have figures of 1000 in that fuel map area and it would still fuel cut.Hence the slight stumble when returning to idle. I have a P06 Hondata ecu. I guess we'll have to wait until hondata says something. Too much theory. I'm drained now.

man,its like 3am & im up for more beating my head against a wall:?

it just occured to me.......a 30lb h22 on barbados right.....if u started from the west side.....wouldnt u like end up in the carribean before u hit target boost???

still dont reckon MAP has effect on sparking off OFC,ive got a log here of going into OFC with MAP input still above the MAPvsRPM value set,ie i have 4000rpm-16kPa setting,but it still OFC'd with ecu still seeing 16.6kPa.

wish i had car to test on would def stop my head throbbin...
maybe u can try an overexagerated MAPvs RPM setting & still see if it OFC's.

the rpm value i assume your talking about is the 1050rpm figure i keep mentioning?
if so,that one is set in stone,it doesnt appear as an adjustment in the software,its just a condition set in the stock honda code to kick off OFC,thats why i believe u dont even need the MAP input to set an OFC because the RPM figure is always there anyway.
different motors have different rpm values for OFC,as i said mine(jdm p72 b18c) appears to be a consistent 1050rpm when the injectors kick back in & i assume it goes to moving idle value then until stationary.
ive also seen an ITR(B18cR) do it at about 1300rpm,so yours could be different again.
dont know how accurate these rpm figures are im quoting,who knows where the datalog gets rpm from or how accurate datalog is anyway,my datalogged rpm values are fairly jumpy,ie not the fairly straightish line u would expect to see,other logs ive seen are the same.

really gotta go to bed,work in 4hrs lol.....night

edit:oh imagine if hondata chimed in & just gave us a little hint at least lol.......

edit edit:just tried read your edit & it was like all blurry & stuff,will read tomorrow lol

ok,theres your problem,after litttle bit research.....

P06 OFC cancels out about the 850rpm mark,almost landing bang on your idle target.

F20,H23 obd1 ecu's cancel about 1500rpm.
obd2 H22's like the P5P about the 1050rpm mark like mine seems to be

so im assuming u were obd2 stock?

guess your gonna have to get a P13,P72 or similar if u want to raise that cut-out(or cut-in point lol) back to 1000rpm or above,unless hondata finds the ability to manipulate this value???

makes me wonder though,that little 1000rpm buffer than drop to idle like u described(cant remember whether my car still does that or not) i wonder whether thats the same function as OFC,its like an electronic version of the old dashpot system my old D16A8 used to have....

I see, so my H22 is not recovering early enough. My stock P13 recovered around 1000rpm and idled at 750rpm. Stock P13 ecu is an OBD1.

Yeah. I guess you can't expect an engine to fall suddenly to idle speed and hold idle without it dropping below. Hence this feature. Well I guess I'll wait until Hondata do something about it cuz I'm not buying another ecu for that feature. No way.

Thanks for the discussion/info. We'll see.