Author Topic: O2 Sensor Affects Idle Mixture?  (Read 2023 times)

0 Members and 1 Guest are viewing this topic.

Offline Nomad

  • antrx.com junior member
  • **
  • Posts: 24
  • Karma: +0/-0
  • Gender: Male
O2 Sensor Affects Idle Mixture?
« on: Oct 22, 2012, 03:23PM »
If this is the wrong section, mods feel free to move it.....

I don't have a Pintara/Corsair but I do have a KA24E engined D21 Navara. The stock Navara runs an Hitachi ECU
without Consult, and being a commercial vehicle, it did not have an O2 sensor or cat converter.
I converted it over to a U12 ECU to get Consult and all the benefits associated with it. During the change over I also
pulled the eprom and replaced it with a socket so I could modify the U12 bin to incorporate the D21 maps.

So over the next few weeks I tweaked the fuel and ignition maps to my liking, mainly the fuel, because the stock fuel
map was very rich. I got them to a stage where it was fairly close to 14.7AFR everywhere but idle was always lean at
around 15.7 to 16.0AFR. My fuel map values in the low rpm/low TP area's were around the 192/193/194 mark and this
worked well, except as mentioned, idle.
The wide band was not connected to the ECU in any way, it was just to monitor AFR's.

I then decided to add the narrow band O2 sensor and let the ECU do it's closed loop thing and get the mixtures to 14.7.
To do this, I bought a new Bosch heated, four wire universal O2 sensor and wired it in. I also cleared the self learn
parameters to start with fresh settings.
This worked a treat. Mixtures were always at 14.7, drivability was great. I could watch the AFR's dance backwards and
forwards slightly as the narrow band and the ECU talked to each other in closed loop. I was a happy man until I noticed
that the idle mixture had gone completely the other way. It was now idling rich at 14.0 to 13.7AFR. This was with the
same chip/bin in the ECU as before.

So, after all this rambling, my question is, why would the idle mixture change so much?
It appears to drop out of closed loop at idle, so I thought it would be the same as with no O2 sensor.
It's not a big problem, but I'm interested to see if anyone else has noticed this condition.
Anyone got any thoughts or ideas?
As far as I know, there is no separate idle map to let you modify idle mixture.

I remember SSS having a post hybridka about idle mixtures years back, but I forget the details.
SSS, maybe you could elaborate/help?
Thanks, Brian.

Offline Nomad

  • antrx.com junior member
  • **
  • Posts: 24
  • Karma: +0/-0
  • Gender: Male
Re: O2 Sensor Affects Idle Mixture?
« Reply #1 on: Oct 28, 2012, 09:22PM »
OK, bit of an update. I had a play 'round with the fuel map cells in the idle area during the weekend.
I have changed the target base idle on the  D21 to 775RPM and Nemesys confirms this.
Idle sits on the 600RPM/6TP cell and stays there once it has stabilized.
After changing this cell to value 172 (from stock 192), and uploading it to the ECU, the idle mixture did not change.
This change should have leaned the idle mixture from its 13.7~14 to around 14.7~15 going by the values elsewhere in the map.
ie: a change in cell value of 10 = approx 0.5 change in AFR, so 20 should give a 1 AFR change.
This indicates there is a separate map or value for idle mixture. But where is it?
Also, watching the AFR gauge and the real time display in Nemesys at idle , I can confirm it stays in closed loop for about 10 seconds, then goes into open loop.
This is where/when the idle goes rich. The O2 sensor reading goes to approx 0.8V and stays there at this stage also.
So, any ideas guys?
« Last Edit: Oct 29, 2012, 12:02PM by Nomad »

Offline SSS

  • Administrator
  • post whore
  • *****
  • Posts: 8270
  • Karma: +5020/-3
  • Gender: Male
Re: O2 Sensor Affects Idle Mixture?
« Reply #2 on: Oct 29, 2012, 02:51PM »
There is an additional flag that activates closed loop feedback, ill try to remember to look through my notes to find what it was.

Offline Nomad

  • antrx.com junior member
  • **
  • Posts: 24
  • Karma: +0/-0
  • Gender: Male
Re: O2 Sensor Affects Idle Mixture?
« Reply #3 on: Oct 30, 2012, 06:42PM »
More weird stuff.
Coz it was hot in Melbourne today, I used the A/C on the way home from work and when the A/C cut in, the mixture got even richer as the revs went up!
Like to 13.0 and into the 12's sometimes.
It seems it's related to AAC/IACV action. I assume the idle is raised by the IACV when the A/C is on and I also assume it just adds air into the intake.
So, adding air makes the ECU compensate and add more fuel? But where does it get its fuel enrichment values from during this phase?
I guess there is an AAC/IACV subroutine somewhere to handle it. Time to search through deviouska's dis-assembly and see what's there.
Also, if I just raise the revs by pressing the throttle while the A/C is on, the mixture goes straight to 14.7, I guess coz it's accessing the primary fuel map, not the IACV.
I'll have to hook up the laptop and see what the AAC/IACV does when the A/C is on. Might give me a bit more info.

Offline Nomad

  • antrx.com junior member
  • **
  • Posts: 24
  • Karma: +0/-0
  • Gender: Male
Re: O2 Sensor Affects Idle Mixture?
« Reply #4 on: Oct 31, 2012, 02:44PM »
I didn't think about it properly. I forgot about the FICD solenoid.
The idle is raised by the FICD when the A/C is turned on, not the AAC/IACV.
Both these are mounted one above the other on the D21 throttle body, FICD on top, AAC/IACV below.
Some investigating to do. I might try disconnecting the FICD and see what happens.
« Last Edit: Nov 2, 2012, 10:14AM by Nomad »

Offline Budgie

  • Dr. B Udgie - AWD FTW
  • Administrator
  • post whore
  • *****
  • Posts: 9411
  • Karma: +131/-33
  • Gender: Male
  • U12-U13
Re: O2 Sensor Affects Idle Mixture?
« Reply #5 on: Oct 31, 2012, 08:56PM »
Keep updating this thread as well Brian, just because no-one is really replying doesn't mean this information won't be of use to someone else in the future. Hope you get it sorted!
dont piss me off with your pillarless shit captain snappy wrist

Offline S1L03T

  • antrx.com pre-pewbie newbie
  • *
  • Posts: 1
  • Karma: +0/-0
  • new skids in my jocks
Re: O2 Sensor Affects Idle Mixture?
« Reply #6 on: Sep 7, 2016, 08:42PM »
Sorry for thread revival, but you are in fact right about this thread being of use to someone in the future lol.

I've just done the same thing, put a u12 ecu into my d21 navara along with a pintara o2 sensor. The issues I'm having is trying to find an ecu pin out diagram for the stock d21 ecu. It seems impossible to find. On plugging my consult in and firing up nistune, i am getting a number of issues.

1. The power steering flag is on all the time; deactivates when a gear is selected (Neutral switch pin out is wrong?)
2. The start signal flag is on all the time unless you aren't idling (throttle valve switch pin out is wrong?)
3. AC pressure switch flag coming on whenever the steering is turned (power steering switch pin out is wrong?)

And finally, the o2 sensor is clearly functioning but I am basically using exactly the same amount of fuel as before (400km to 60 litres, highway driving)

Any of the hard body manuals I have found all have the same pin outs as defined in the u12 ford corsair fsm, yet on closer inspection and tracing these pins, the start signal with the d21 is in fact in the right spot, the air con switch is in the right spot, the power steering switch is in pin 44 when its pin 43 in the u12 fsm, and pin 44 is the Throttle Valve Switch Power Supply on the u12. However, pin 43 is a direct earth with the factory d21 ecu (Traced it to a screw and eyelet next to the ecu). So i could see why the power steering flag was always on as it was earthing as if the switch was active, so that pin definitely needs to be removed. Moved the power steering switch wire to its correct pin (43), confirmed it was in fact the power steering switch wire, but still no change apart from it not activating the ac flag, which was strange, seeing as that pin (44) is the Throttle Valve Switch Power Supply on the u12, which means that from the moment i plugged the ecu in and went to steer, it would've short circuited, as it would've opened an earth directly to the ecu's 8-10v Throttle Valve Switch output.. Checked that there was 8-10V as the fsm diagnostic describes, there was. Somehow. Confirmed that the neutral switch was in fact the right pin, so i have no idea why its triggering the wrong flags.

Maybe somehow it's fried circuits because of a different pin layout... thats what i wanted to know from day dot, is can i plug and play.. I'm anal when it comes to these things, i've done many successful conversions with rb's, ca's and so forth. I like to have everything working as per factory installation, pin for pin.

There is bugger all information to support such modification, or the fact that Australian d21's have a different pin layout. I really need a pinout for the aus spec d21, otherwise i'm going to pull out a loom of a wrecked d21, and reverse engineer that. I also spent many hours compiling a pinout document for the u12 ecu, all pinouts are correct and were compiled from the fsm. I just made a reference document like many other nissan engines have, but not the ka24e. I just need to work out the differences, as clearly there's something different between the two.
« Last Edit: Sep 9, 2016, 07:57PM by S1L03T »

Offline Nomad

  • antrx.com junior member
  • **
  • Posts: 24
  • Karma: +0/-0
  • Gender: Male
Re: O2 Sensor Affects Idle Mixture?
« Reply #7 on: Sep 27, 2016, 09:19PM »
Don't worry about the flags being different. I emailed Peter Collins of ECUtalk about the same thing.
I get the same as you:
Pwr Stg SW = Neutral SW (ie: move gear lever into & out of gear and the pwr stg sw gauge changes)
Start Signal = Closed Throttle
Clt Fan SW Hi = Clt Fan SW Lo
A/C Relay = A/C Relay
A/C On SW = Pwr Stg SW
Peter indicated the KA24E probably has unique digital bit register outputs for some reason.
On to the ECU swap, the main differences between the U12 & D21 are the addition of Consult capability (Pins 7, 14 & 15),
the O2 sensor on Pin 19 and the idle-up for headlamp (pin 27) and rear defog (pin 42) load.
Pin 42 wire must be cut for the ECU swap as it was an earth in the D21.
When I did my ECU swap it was basically plug and play, all I did was add the shielded wire from Pin 19 to the O2 sensor, the Consult connections and cut the wire to pin 42,
all other pinouts are the same or not connected. So the US spec wiring diagrams are 99% correct.
The main difference on drivability and fuel consumption is the different MAF curve between the D21 and U12. The U12 curve results in rich running conditions.
I added a U12 MAF and disconnected the D21 MAF to my conversion.
PM me with your email address and we can continue this with pictures, charts, etc to clarify things.
« Last Edit: Sep 27, 2016, 09:26PM by Nomad »

Offline pedro666

  • post whore
  • *****
  • Posts: 2326
  • Karma: +26/-8
  • Gender: Male
  • VET NEO VVL is how I roll...
Re: O2 Sensor Affects Idle Mixture?
« Reply #8 on: Sep 28, 2016, 07:00PM »
great info Nomad, would be great to have any extra diagrams etc posted up for future reference. do you have the antrx chip, or just stock ecu?
the words "race car" spelled backward still spell "race car"? 




skype_shannan801

Offline Nomad

  • antrx.com junior member
  • **
  • Posts: 24
  • Karma: +0/-0
  • Gender: Male
Re: O2 Sensor Affects Idle Mixture?
« Reply #9 on: Sep 28, 2016, 10:46PM »
I bought a Stage 3 antrx chip off Pure_Sincerity a while back but have not installed it yet.
My ECU is chipped but with mods I have done myself with info from here and from the old ECCS-hybridka/ECCS-tech sites.
Just a few basic changes, +1 degree of timing over the whole map, much leaner fuel maps, etc.
« Last Edit: Sep 28, 2016, 10:57PM by Nomad »

Offline Nomad

  • antrx.com junior member
  • **
  • Posts: 24
  • Karma: +0/-0
  • Gender: Male
Re: O2 Sensor Affects Idle Mixture?
« Reply #10 on: Oct 29, 2016, 08:13PM »
The other major change I forgot to mention for the ECU swap is static or base timing.
The D21 is 10 degrees but the U12 is 15 degrees.
So when you convert to the U12 ECU, you need to adjust the base timing to 15 degrees.
Refer the U12 or D21 FSM. Basically, disconnect the TPS and rotate the distributor untill you get the timing light to the 15 degree mark.
If you don't do this, your timing will be retarded and performance wil suffer.
Cheers,
Brian.