Ignition timing in live data at idle

I bought an OBD2 scanner and scanned my two current vehicles just to familiarize myself with it. Both vehicle engines run and sound excellent with no codes. My 2000 Tacoma 2.4 double overhead cams (140,000 ) shows rock steady 9.5*-10* advance at idle. My 2007 Kia 2.4 double overhead cams (127,000 ) shows 3.5*-15* (rapid ups & downs) advance at idle.

My question, is this a sign that my timing chain is worn?

(no timing chain noise, no metal debris in oil, runs and sounds excellent)

if your idle is fluctuating it can cause that.

Thank you for the reply but …….idle is rock steady, no rpm fluctuating at all.
If I didn’t have the live data I wouldn’t suspect a thing.

The timing you are reading is IGNITION timing not VALVE timing which is controlled by the cams and timing chain.

The ignition timing on your Kia varies a lot because it is used to stabilize your idle speed. It is faster to adjust idle speed with ignition timing than with the electronic throttle.

The Toyo is old enough to have an idle air control valve to adjust idle. No need to adjust timing.


You have taken a big load off my mind and I thank you very much for taking the time to answer.

Being from the tach and dwell with points era, I couldn’t understand why my perfectly running and sounding engine would show such a wide variance in timing at idle but run perfectly otherwise.

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