Issues with AFR's and Idle on z32

[MagicMike]

Hi Team,

I have recently done an injector upgrade on my vg30, from nismo 555's to jecs 1000s.

I was using the JECS in my last z32 and they worked well. I am having issues after the install of these injectors in my new zed however.

I did the injector resize and the engine idled like crap.

Adjusting the kval and latency, I can get a rock solid idle with good afr's. I have disconnected factory O2's and removed fuel map feedback. Then when I go for a drive my afr's go instantly very rich (10:1). I pull over to the side of the road and make changes to the map and go for another quick drive and my afr's come to a more reasonable 11.5 to 12:1, however when I pull over again and come back to idle, the idle is really lean now (between 17:1 and off the gauge scale) and as such idles very rough.

I don't understand what can be causing this when I have not touched anything to do with idle? Or am I missing something?

Being that I had these injectors tuned in my last zed I had a good set of values to start from with the new zed.

Any thoughts or suggestions please gurus?

[Matt]

Resizing injectors means that you have changed K constant. This in turn affects TP scaling used on the fuel and timing maps

You need to adjust your TP scaling to suit the larger injectors now. This is detailed in the tuning guide and workshop tuning information training slides on our website

Once you have the scaling fixed up try it again and get a log of the run with AFRs as well as your BIN file to post here if you are still having issues

[MagicMike]

So an update on this...

Had a mate come round and he loaded up a brand new bin from his own laptop, which was then modded, and the car was much more stable. On a side note, my o2's were stuffed so the feedback was turned off.

Since then I installed new o2's and fired it up. O2's were reading as expected, so I turned feedback back on, and attempted to burn back to the ecu. At this point, I got a syncronization error. I then re-synced and burnt to ecu.

At this point, I noticed that the o2's stopped giving a reading at all (in both nistune and consult). 0.00V, flat out reading nothing.

Is it possible that the sync issue has made some tables go places they shouldn't?

[Matt]

It shouldnt. The sensors should always be reading in consult. You can verify by checking the sensor input into the ECU with a multimeter (using paperclips on the probes) to check the voltage

The sensor reporting in consult should show over 0.5 volts when AFRS are higher than 14.7:1

[MagicMike]

Ok. So I uninstalled the older version I was using and installed the latest. Haven't had an issue with o2's since.

What I have found, is that generally idle afr's are stable and load afr's are functioning correctly (after much fiddling).

Sometimes after load coming back to idle, afr's go strange. Slowly leaner and leaner and then back to normal. Then leaner and leaner and then back to normal. I noticed that injection duty does not change anymore than it does when idle is stable. Afm voltage increases slightly as revs increase with leaner condition.

This happens occasionally when at idle. I can give throttle a rev and once revs come back down and afr come back to normal, idle generally remains stable.

This hiccup can happen directly after a hard run of load, and also after prolonged idle time (think minutes, 5 to 10mins).

Any ideas?

[Matt]

Watch the O2 sensing LTFT and STFT which is based from both O2 sensors. This will change your AFRs by the % of trim of each

[MagicMike]

Made 535.9rwhp @ 22psi on Thursday.

Was increasing boost further when we encountered spark blow out, so need to upgrade ignition now. Didn't even get to start bringing timing back in

Still having idle issues tho No matter what I do I can't get SFT consistantly under 12% and LFT under 8%.

[Matt]

We would try a firmware update on your board to put K to factory and use the new Injection Adjust feature. Shoot me an email if you want to try that out

[MagicMike]

Would love to try that Matt

Firmware upgrade include the flex capability?

[Matt]

Yes it will. I've just got to finish some updates. Was meant to be today... but didnt get a chance to even start

I've added in a 16x16 flex fuel map into the firmware and we tested last night on the S14. All good so rolling those changes out through the other ECUs. Should be available next week depending on my hand (having another operation for my finger which got busted back in Feb)

[MagicMike]

Ok cool, hope the op goes ok!

I'll hold off til then and touch base in a week or so.