advanced timing.... maybe

89 renix my timing seems to be at around 16 to 18 degrees BTC at a low idle (300-400 rpm) i am chasing a low idle issue and am now needing to find what is causing the ecu to advance my timing. or is 16 to 18 normal? i know there is no way to adjust them, but there has got to be a base timing number for the most part. anyone know?

There is no base timing number.

However, for the Renix, there were (and can still be) "high-altitude" crank position sensors.

Do a search, been discussed here quite a bit.

thanks. i do know about the high altitude CPS but did not check the numbers on all of the ones i have to compare. might have to do that. i was just hoping to find an "average" renix timing. i have read 12 BTC by google, but was just hoping some of the naxja guys may have checked theirs at one point so to get a reference.
on a side note i did a leak down test today and found 15% on #2#3#5#6, but got 25% on #1 and 30% on #4. could be why the ecu is changing timing and air/fuel.

A sticky EGR valve will lower your idle. Plug off the vacuum to the EGR and see what happens. Rap the top of the EGR with a screwdriver handle and see what happens. Don't unplug the EGR solenoid, the default is open and the ECU can't shut off the EGR at idle and throttle closed while driving.

Plug off all of your vacuum lines except the fuel regulator and maybe the brake booster. Most times a small vacuum leak will make the idle higher, but it is possible, if not likely, a small vacuum leak can cause the ECU to richen the mixture. I've had mine lope at idle with a small vacuum leak, the ECU couldn't seem to make up it's mind and find the proper air fuel mix or proper IAC position. Only happened on a hot motor.

I think a TPS issue is the likely cause or the O2 sensor on a hot motor.

There is a factory air bypass adjuster under a lead cap on the side of the TB. Most times it is screwed all the way closed. But some motors have it opened a bit, the bypass fills with junk and gets clogged. Most times adjusting it does nothing, the O2 sensor and IAC compensates. But there does seem to be a magic spot on some motors, so it does do something, I'm just not sure what. If yours is set slightly opened from the factory, make sure the orifice and passage is clean. I remove the adjusting screw (torx), counting the turns, clean everything out and reassemble.