S14 SR20DET holding on to closed loop??!?!?!

[beast_man88]

hi everyone!
first post of desperation...

I have a annoying problem that i just cant work out. not sure if im doing this all wrong but i have got the car running quite smooth at the moment. the problem being is when i go WOT from low rpm. it will hold closed loop right up to 3500rpm regardless of the O2 flags. i start making boost from like 2800rpm and full boost at about 3900rpm. but below 3500rpm feels slugglish as its holding closed loop outside the flagged area.

Z32
Nismo 555cc
walboro fuel pump (stock reg)
exhaust
front mount
TD06 20G 8cm
running up to 23psi
Car is a S1 S14: 23710 74F01

i will attach a bin file and a log. i havnt really touched the timing map yet but its not knocking.

sorry for the shitty log. drive home from work today... there is a couple of WOT runs in there. keep in mind i have 110kph cut on the closed loop just to see it work. should also add. "LAFR" is my wideband.

any suggestions would be greatly appreciated!

[beast_man88]

The car was doing this before any tuning was done, so it seems strange. Any bin file i use still does this. Maybe the ecu itself?

[Eric]

sounds like you have the same problem as described here:

viewtopic.php?f=12&t=1702

I'm not sure there's a good solution for it (yet)

[beast_man88]

Thats sounds like the same issue to me. Surely this isnt happening to everyone though... Im screwd for lower rpm high load. The O2 sensor just fights off the fuel map until pretty much exactly 3500rpm.

[beast_man88]

If only the "closed loop cut" table worked off rpm instead of road speed.

[Adrian]

Hi
I have the same problems. I’m wondering that there is only a handful of people which have noticed that. I tested out many different ways to understand how the O2 feedback works, last night. I think there should be another O2 map in the ECU.

I have a solution to run the right AFR. pm me for that....

[skylinegtrhr]

I presume it's EDM S14a? What ECU number and what ECU image is on it?

[PL]

Hi A&M,

That's some interesting info. Good work with the investigation.

I'm currently looking at the self learn parameters to try and find out how they work. We all know what their job is but finding out the detail is another thing. I agree with what you did - and I've had similar experiences. I've tuned so that I saw 14.7:1 at low load with O2 sensing off and then turned it back on only to have the ECU add/remove fuel once closed loop was enabled.

I've been speaking to Matt about this and I think it'd be worth having fuel trims available in the gauges panel or maybe even as part of the fuel map window - depending on availability of screen space).

The other thing is naming them - traditionally in the Nissan ROM tuning world they've been known as AF Alpha and AF Alpha Learn. Terms I found somewhat confusing. Most other tuning systems seem to refer to them as Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT). Would it be worth going to the more generic STFT/LTFT terms? Or stay with the traditional Nissan terms of AF Alpha and AF Alpha Learn? What do other people think?

PL

[skylinegtrhr]

Maybe it's better to stick to Nissan terminology , so it doesn't make confusion if some one is reading OEM FSM .

Same problem was with TP limit AKA boost cut and in "internet tuners" terminology "fuel cut" - Nissan's fuel cut term was something different...

[Adrian]

I presume it's EDM S14a? What ECU number and what ECU image is on it?

Yes you're right. It's a european ECU 75F00 i've used aslo the european base image. I don't know if there are any difference to the JDM or US base maps.

The two TP values higher than TP34 witch i hadn't know in the last post are TP 40 and 48.

[skidder]

Hi Guys,

Where can you look at the Short term and long term fuel trim/ Or AF learn as it seems to be called?

I've been wondering if I can use the long term fuel trim to validate my K constant. But what iv'e just read above suggest that the target AFR's in the table is not the only thing effecting closed loop operation....interesting...

Any help appreciated...

Thanks

[Matt]

AF alpha and AF alpha learn are short and long term trims (names that Nissan uses) respectively

[skidder]

Hi all,

I have this exact same problem. Its really anouying. I cant use high load at low RPM. Ie under 3500 ish. The car just holds onto closed loop.

The more confusing this is i have 02 sensor disabled in nistune and the 02 of in all the cells. Seems to make no difference. For some reason the 02 sensing is still on....

Any suggestions?

Thanks

[Adrian]

Hi all,

I have this exact same problem. Its really anouying. I cant use high load at low RPM. Ie under 3500 ish. The car just holds onto closed loop.

The more confusing this is i have 02 sensor disabled in nistune and the 02 of in all the cells. Seems to make no difference. For some reason the 02 sensing is still on....

Any suggestions?

Thanks

As i writed ahead:
[color=#0000FF pm me for the solution.

[diehard]

Bumping this thread,
I have the exact same issue, S14a 83F00, z32,550cc.
Car holds closed loop with o2 feedback switch off and o2 off in the cells, doesnt go into open loop till 70 TP (10psi)
I had to put o2 on in the cells (o2 feedback switch still off) all the way up to this point for the ecu to go into open loop and read the fuel map cells.

so tldr; o2 on in cells = open loop, o2 off = closed loop, the backwards of how it should work.

o2 in cells off

o2 in cells on