Dear Scotty,
my 1996 Mustang 3.8 V6 with 64800 miles shakes a little in idle. I hooked on my Anyscan A30M, thank you for your recommendation. It's adding 5% fuel but the mass airflow looks fine. No misfireing.
But the spark advance in idle is bouncing around between 18 and 21 degrees.
Could it be the crankshaft damper or a worn timing chain? Should I fix it as soon as possible or can I live with it?
Thank you for your help.
Olaf
Moving between 18 and 21 degrees isn't really bad enough to warrant replacing the timing chain, I don't think so, at least. My '99 Ranger goes from 12.5 degrees to 15 and back. I'll notice it run a little funky every once in awhile, usually when I'm idling for a long time. If the check engine light isn't on and a slightly rough idle is all there is, that's no real problem. It's a 26 year old car. Haha. It might throw off your fuel trims a bit. Keep the oil at the right level, don't drive like a freak, and change it often, it shouldn't get any worse.
You might not even be feeling the ignition timing difference. My truck was running -11.9% when I really noticed it running weird. I ran fuel injector cleaner several times, they came up to +/- 2.5%, and I hardly notice it now, you may be feeling the effects of vacuum leaks.
Spark advance bouncing around is a symptom of a stretched timing chain, though it could be just the tensioner. Since fuel is being added I'd check for vacuum leaks, especially if the car still has original 26-year-old rubber hoses.
It's adding 5% fuel
LT or ST?
5% isn't that bad.
if there's no misfire I wouldn't worry about it too much
Yes, thank you. The hoses are all original. I'll check them. And I'm thinking about to replace the timing chain. It's not that expensive but a lot of work.
Check engine light wasn't on. I think I'll check for vacuum leaks first.