Nistune Forums

Hello,

I have a problem regarding the FTS behaviour on my Nistune ECU.

Currently I have a 44F ecu (suspected, case says it's 39F00 but I found a MEC-D009D eprom inside) with 39F00 nistune board. My car has an O2 loom. I'm running stock AFM and injectors for now.

In nistune I can't see O2 signal (It's stuck at 0 volts flat) but my FTS is acting on its own and my AFRs react to that. It doesn't matter if the O2 flag is on or off.

Is there anything that effects the FTS value other than the O2 value? The only connection I found in the logs is between the FTS and the throttle values. Whenever throttle is applied, FTS slowly rises till it hits %25(max).

Below you can see a screenshot of a cruise log, and the log itself.

Some fuel trim outputs (Z32 and it appears this) will be affected by throttle enrichment as well as closed loop. So its not just fuel trimming in this case (since you had disabled it) but extra fuel based on TPS position for extra acceleration enrichment

That is a common problem on CA18DET
The ECU mainboard between 44FXX and 39FXX is different,
44FXX ECU is non Anti Pollution ECU, does not have 02 control (does not produce 0.32V 02 signal), it require 4 pin AFM.
39FXX ECU is Anti Pollution ECU, it has 02 control, require 3 pin AFM, it will produce a 0.32V default 02 signal voltage if you unplug the 02 sensor, and the FTS is always stay 0% all the time, 02 feedback control activate only if you feed a 02 signal (wideband or factory 02 sensor)

The problem you have is the 44FXX ecu does not produce the 0.32V signal, and your nistune board base program 39FXX seeing 0.00V 02 signal, and 0.00V means lean, so it keep on adding fuel.

If your engine wire have a 02 sensor plug, thats mean your MAF plug is 3 pin, and you will need the 39FXX ECU. (Buy a 39FXX ecu and swap the nistune board to the new ecu is best way to fix this problem, no extra work to do except the nistune board installation)
If you keep on using 44FXX ecu, you have to reprogram the nistune board to 44FXX base program, and change the MAF to 4 pin MAF, the extra pin is for idle mixture knob on the 4 pin MAF (ie : and you have to manually add the extra wire to the ecu, otherwise you idle mixture will not correct)

So either swap the ECU or return board back for reflash to match the ECU

Does your ECU match the vehicle? 3/4 pin MAF?

Dear Matt and Louis,

Thank you for your input.

I have the 3 pin maf right now, soon I'll swap it with a RB Maf.

I'm planning to buy a base image programmer(It would be good to have the new features anyways). There are no shops in my country who can do it for me, and shipping things out is a bit problematic here. Maybe I can help future Nistune users around me.

If I can't also swap my ecu with a 39F and stay on 44F with my nistune flashed to 44F, do I need to wire in a potentiometer for the idle trim with an RB maf?

I'll also try to find the hardware difference between the 39F and 44F boards. I've previously read that an op-amp is missing in the 44F boards feeding the o2 heater. Maybe I can replace what is missing circuit wise.

Many thanks, cheers.

You can try adding a pot to the ECU wiring. However we notice you can tune around the pot (on the RB30 models which have this also) by moving K constant so I dont think that will be a big issue

Dear Matt,
I bought another ECU, 39F05 this time and transfered my Nistune to it (Nistune base 39F00, closest I can find was 05), but I still can't see the o2 signal.

I checked my loom for continuity and shorts, updated nistune editor to the latest, tried enabling/disabling the o2 flagg, connected a brand new o2 sensor; but the o2 readout in Nistune is still at 0 volts (not 0.32V).

Can this still be caused by a mismatch (39F00 vs 39F05) ?
I'm also seeing a knock sensor error, can that disable the o2 for some reason?

Regards,
Ozan

Knock sensor should only affect timing (not closed loop) from what I know about the knock sensing for these ECUs

You need to fix that problem firstly anyway

I'm not sure with differences between 39F05 and 39F00 hardware to cause this issue. One thing to check is with a multimeter the O2 sensor input line to the ECU to see if there is voltage there

I dont have 39Fxx hardware here to check. The 36F11 ECU I have at the moment with EDM 39F0F (39F00 Feature pack) shows O2 voltage fine even with Jap ECU hardware

I'm happy to report that I finally got it working.

The problem was with the loom. I cut the corresponding cable on the ecu side and I was finally able to see the magical 0.32Vs. Before, I checked the loom with a multimeter with the car off and ecu not plugged. I guess there is a heater relay that comes on when the ignition is on so that masked the issue. Something was pulling the o2 input to the ground.

I had a short observation but the erratic FTS behavior seems to be gone (at least on idle).

Good stuff!