engine timing

[careldo]

Hey Guys,

Last night i was just scrolling trough the DIC for no particular reason and decided to look at the PCM data.In doing so i came across one data point which is supposed to indicate the the timing degrees as the pcm is seeing it.Well to my suprise it was reading 7 degrees instead of 10 degrees (4.9 engine) but two weeks ago when i checked the timing with a timing light following the correct procedure as outlined in the manual i was reading 10 degrees.Is it possible the marker on the water pump is not in the correct position (pump not original)thus giving me an incorrect reading?

Should i reset my timing using the pcm data point to make sure the timing is correct?

thanks in advance for your help.

Careldo

[JasonA]

As I understand it, the timing isn't static at all -- it's changed by the PCM according to RPM...ie, there's more spark advance at high RPM. The 4.9L engines didn't get knock sensors, so there's no timing adjustment based on spark knock, but there should be some for RPM. Perhaps you set the timing with the throttle kicked up a little bit (1500 rpm), or while the car was in Park, and maybe this time you checked it while it was in Drive?

[Dan]

The 4.9 is really tolerant of the timing being a little off. I replaced the distibutor a couple of weeks ago and I had the timing set at 20 degrees (by accident) and the car still ran.

[careldo]

Thanks Bboynski, you have fully answered my question and yes to your question on setting the timing.

I run premium all the time, octane rating 91 to 94 depending on price so you know what I'm doing this weekend bumping my timing up to 14 and going for a nice ride to the country side.

[careldo]

Gave them a good cleaning last summer, i guess i should give a good cleaning again for continued enjoyment.