Yes, timing can vary a lot on these vehicles because timing is PCM controlled (not distributor controlled) and it can instantly change it to anything it decides. As long as distributor rotor is pointing at the correct terminal, distributor has no affect on timing. But when the spark does come through the rotor must be pointed correctly or the spark will jump internally and cause a misfire. The correct rotor orientation is read by the "Cam Sensor Retard" PID. This is a common cause of misfire on Blazers and late 1990's Vortec V8s (same fuel injection setup), and why its important to have a scanner that can read this GM enhanced PID. Just something that is always suspect and should be verified on these vehicles. Distributor gear wear is usually the culprit, but stretched timing chain can also cause cam sensor retard to be off. Spec is zero degrees plus/minus 2 degrees.

 

you can take the belt off to tell which. FWIW a 2002 should have a tensioner on the timimg chain

 

I honestly didn’t think of that🤦‍♂️. I have put in a whole new distributor, cap and rotor from oreillys, so it would be safe to rule out the distributor gear. When I put it in time I checked the chain wear through the rotor by turning the engine in either direction and it moved instantly with no hesitation. Are there any reasonably priced scanners that will read what I need and be able to adjust if need be?

 

Either Dash Command or Car Diagnostic Pro will read it. Thats about all your inexpensive options for cam sensor retard.

 

is this the app you’re talking about?

 

yes, thats it! Remember WiFi if you have iphone. Bluetooth if you have android.

 

so I pulled out my Dist cap that I put on before swapping my distributor and spark isn’t hitting the terminals in the center. It’s more to the side of them. As soon as I pulled in my driveway last night my radiator gave out 😒😒

 

Sorry to hear that.

Position on the distributor terminal receiving the spark depends on the timing at that moment. So the rotor position is set so terminal is "reachable" throughout the timing range. Running down highway will make different visible pattern than will idling around town. Only way to accurately check/set is with cam sensor retard.

 

sorry I’ve been MIA been down for a bit with Covid and finally feeling better. So I got to reading on spark plugs… and I cheaped out when I replaced them the first time and went with the cheapest. So yesterday I went and but the bullet and bought ACDelco iridium plugs and my miss is totally gone now. I still have the code p0101 though and when that code is on it absolutely will not shift into OD