KA24DE Diagnosing with Nistune

[iyarovoy]

Hey All,

I would like to use Nistune as a diagnostics tool as well as a tuning tool to find out if the engine is running correctly. Here is where I need your help with my car.

Engine: S13 KA24DE Auto to 5 speed swapped
Timing: 20Degrees (set using "Active Tests" in Nistune and using a timing light)
Injectors: 1.5 years old STOCK
Fueling: Tomei FPR set to 43psi w/o vacuum, 36 at idle w vacuum
Fuel Pump: Good. Tested by mounting FPR and gauge on my windshield and wife monitoring pressure while I do some hard pulls. Does not drop PSI.
Sparkplugs: New NGKs gapped
Wires: New NGKs
O2: New Bosh Universal
Vacuum Leaks: Built a smoke machine using metal Paint Can, brass nipples, clear tubing, mattress air pump, insents. No leaks. All hoses were replaced just for the hell of it, including removing the manifold to get those hard to reach ones. Air leak was found where the Air Controller connects to the lower portion of the intake manifold, now fixed
PVC Valve: New , including the hoses that connect it to the manifold
Distributor: Cap and Rotor 1 year old

Problem: My Fuel Trims at idle are crazy. LTFT at +10 and STFT at +18. Does that indicate that I still have an air leak somewhere? Car idles great. Occasionally it will dip into the 600s RPM when coming to a stop and then bounces back up after stopping. Any suggestions would be great.

I attached some logs so those who are curious can see the driving and idle behavior

I'd like to try and maybe have a topic page of engines that have faults and the logs associated with them. (O2 sensor bad, vacuum leak, boost leak ect) as a reference for others.

Thank you

[Matt]

As long as at idle you are seeing around 14.7:1 on the wideband then I would not be concerned about the trim values. Some Nissan ECUs (like Z32) will not show actual trim % at idle (only when off idle during cruise conditions) so in those cases like idle the trim values are not correct.

You can try and lower TP minimum around the area where it appears to have too much fuel to see if that helps with the drop to 687rpm idle

[iyarovoy]

Thank you very much for the help.

Is there any value in noting that at my Load Index does not go below 12 during idle, so essentially the left side of my Fuel and Ignition timing maps is never accessed?

[Matt]

This may be caused by TP reading higher than normal due to K constant being increased or slightly higher than normal MAF reading at idle

TP = MAF(VQ) x K constant / RPM

TP min table will limit the minimum value allowed here (looks like this table is TP / 8 perhaps for this ECU) so reducing may help