1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, Slightly Erratic Ignition Timing in Past Cadillac Vehicle Discussion; Hi guys. Question about timing. Long time ago when I hooked up a vac pressure gage, the vac at idle ...
- 10-18-13 01:17 AM #1Cadillac Owners Member
- Automobile(s): 1992 De Ville Sedan
- Join Date
- Oct 2013
Slightly Erratic Ignition Timing
Question about timing.
Long time ago when I hooked up a vac pressure gage, the vac at idle would generally hold steady at 18 inHg and very slowly fluctuate between 17..19 inHg. After doing extensive googling, I found the probable cause was likely a problem with ignition timing. Indeed, when I put the PCM in timing mode by jumping the ALDL connector, the base timing is supposed to be 10 deg before TDC, but the timing mark on the pulley actually oscillated between 12...8 deg, which would explain the vac gage fluctuation. This has been going on for years now and I would like to fix this if possible. What would be causing this? Timing belt too long? Distributor shaft gear worn out? Anything wrong with the distributor itself? What would be the most likely suspect to look at first?
The car has 210k miles on it, 92 deville, 4.9 motor.
Any input appreciated.
- 10-18-13 10:24 AM #2
Re: Slightly Erratic Ignition Timing
Distributor gear, timing chain/sprockets, (?) distributor advance flyweight spring(s).