I posted this in alt.autos.4x4.chevy-trucks but thought I would post it here just in case anyone has some insight that doesn't read the other.
Vehical: 1999 Chevy Silverado Z71 4x4 Extended cab,. 5.3 liter automatic with 143k miles.
I've had this truck for almost two years now and it had 89k miles on it when I bought it. I'm about to replace the plugs, wires, and at the very least both pre cat O2 sensors here pretty quick because I have no idea when the last time any of these part were changed and I'm sure some are original.....
I've always had a problem with the motor missing when it's hot out but it's not limited to just when it's hot sometime it'll do it cold but it's certinally worse when the weather is hot and the truck has been driven for awhile. I normally run regular unleaded (86 octane) and have tried running a tank of 89 octane through her and nothing really seemed to change.
The check engine light has come on several times since I bought it but it always either goes off by itself over time or can be reset wtih a scan tool and it wont come on for another extended period.. The only code I can remember pulling are knock/miss codes, you'll have to excuse me I can't remember the code number off the top of my head.
Besides the fact that I want and really need to change these parts anyway does anyone have any ideas what else I need to look at? What about the knock sensor itself? Crack sensor? I honestly think that the O2 sensors are the biggest part of my problem next with plugs and wires. I'm considering pulling all the plugs and checking condition and gap before I purchase just to make sure it's not something that simple. The truck used to have a K&N air filter but I have since replaced it with a Wix HD filter and when I did I cleaned the MAF with electronics cleaner just to make sure it didn't have oil all over it any likely hood of there being a problem there?
I've also noticed a problem with the motor back firing in the exhaust at high rpm at road speeds.. I'd say it happens if the truck down shifts going up a grade around 4krpm.
Suggestions Welcome before I go spending money I don't have! :)
Adair