Weird timing issue.

[GavinJohnson]

Car is a 90 240sx with an rb20. Running nistune, 555cc injectors, z32 maf, and some other stuff that's irrelevant to this issue. My consult says 26 degrees of timing. My timing light Said 43 Car goes to 7 degrees under load then 60 under boost. For some reason my timing is way out and I can't figure out why. So far ive replace knock sensors, coolant temp sensor. Readjusted tps.

[GavinJohnson]

Ok so anything off idle it goes to 60.

[Skym]

It's normal to be 15-20 (manual / auto) degrees BTDC (Before Top Dead Centre or before piston reaches top of cylinder) at idle in Nistune tuning software and ECU adds what's on the ignition map cells to the 15-20 degrees BTDC. It can fluctuate, as ECU is using different cells with different ignition timing values on ignition timing map. You can datalog this with cursor trailing on via ignition map and play it back with Nistune tuning software.

ECU relies on CAS being set correctly at 15 degree BTDC (manual ECU / transmission), as the ignition timing values on ECU are added to that.

Be aware that when setting CAS, ECU idle stabilisation feature can vary base ignition timing (15 degrees BTDC figure) + or - 5 degrees or so which makes CAS hard to set. Airleaks, unstable idle A/F ratio, etc can make idle unstable.

Some go direct to coilpack 1 on front of engine via a separate wire and not use the black wire on back of engine near ignition module, because ECU sends the signals to adjust ignition timing to coilpack 1 at front of engine on that black wire when idle stabilisation is engaged.

[GavinJohnson]

Yea I did that but it's at 60 with any gas at all.

[Skym]

Sounds correct for stock ignition map, as say I take auto trans / auto ECU 20 degrees base ignition timng + reving at idle with 43 degrees max on ignition map, it should = 58 degrees. Under boost (high load) it should be 47 degrees or less unless ECU has been retuned which adds ignition timing to 47 degrees and depends on how aggressive ECU retune is.

Also don't install the latest version of Nistune tuning software, as person at Nistune took it down. It has calculation problems that he hasn't quite fixed. Use the version he has on the website in downloads page.

[GavinJohnson]

It doesn't fluctuate at all. Just goes to 7 then 60. I have a log if you want I can email it?

[Skym]

Email log to Matt at Nistune. He knows way more about the inner workings of the Nistune software than I do.

[GavinJohnson]

I posted it. Just waiting on a reply

[GavinJohnson]

Figures it out. Well matt did. My timing map somehow got wiped out.

[Skym]

Was it accidently done while setting up injectors (wiped ignition map instead of fuel map before adjusting K setting)???

[GavinJohnson]

I'm not sure yet. Going to check it as soon as I'm off work