98 rodeo- timing WAY advanced by PCM


dclegg61
04-19-2010, 04:49 PM
timing on my rodeo seems way to advanced. Spec 12 degrees, reads 19-20 degrees at idle and up to 45-50 degrees while accelerating.

Looking at data from each sensor on my OBD2 scanner. But I need a resource to know what each should be, so I can pinpoint the problem. Any suggestions?

dclegg61
04-19-2010, 06:48 PM
forgot to say engine has to spin for several seconds before it starts

Cat Fuzz
04-19-2010, 07:13 PM
I'd begin by looking for vacuum leaks. When unmetered air gets into the engine, the PCM compensates for the lean condition by increasing fuel which increases the engine speed which advances the timing.

dclegg61
04-20-2010, 02:15 PM
I searched the engine over and couldn't find any vacuum leaks.
One other thing, that I think is just coincidental, This started a few days after I replaced the timing belt, tensioner, and pulleys. But that thing was so tight that I almost couldn't get the belt on, so I don't THINK it could have slipped.

Cat Fuzz
04-20-2010, 03:08 PM
Well, I tend to think that if you don't have a CEL you everything should be ok. That little bit of advance at idle isn't a concern and the timing always advances when accelerating and higher RPM's. I hooked up my scanner and I'm also idling at 19 degrees advanced and 800 rpm's.

I'm thinking it's nothing to worry about. If your timing belt jumped even one tooth, it would run rough and totally crappy.

dclegg61
04-20-2010, 09:49 PM
Well, I tend to think that if you don't have a CEL you everything should be ok. That little bit of advance at idle isn't a concern and the timing always advances when accelerating and higher RPM's. I hooked up my scanner and I'm also idling at 19 degrees advanced and 800 rpm's.

I'm thinking it's nothing to worry about. If your timing belt jumped even one tooth, it would run rough and totally crappy.


Thanks Cat Fuzz!!! the timing must b ok. I was pretty sure teh belt was still ok
Thanks again.!!!!!

Add your comment to this topic!