First I will apologize for not giving as much information as I could have from the beginning. I consider myself to be a very educated diagnostic tech from past experiences and employment history, unfortunately, I have none of the scan equipment that I had at my disposal while working for GM Milford Proving Grounds as a prototype vehicle tech. I have had the vehicle scanned at auto parts facility and the codes that were set were issues with the camshaft positioning sensor and crankshaft positioning sensor. If I remember it correctly, I was told the codes said they were "out of sync". In my opinion, my best guess was that a vehicle with 244000 miles could quite possibly have a timing chain with enough wear to cause this symptom. But I might be wrong for thinking this. I took a back yard mechanics approach at resolving the issue by replacing the mass air flow sensor, but it did nothing for the issue. I will include this information as a help to you (if I haven't bored to the point of not reading further) I replaced the fuel pump at 175000 because of failure and the vehicle has good pressure (tested vehicle with fuel pressure gauge installed on fuel rail tap while driving). I replaced the tps last month because of failure (3000 rpm idle). I have checked for vacuum leaks. None found, I have inspected all components visually but have not dug into the voltage testing on each individual emissions components as I should do. I was hoping to research forums with a quick resolve for this problem from someone who has experienced the same issue. Final comment, I could go to dealership with my check book in hopes of better scanning equipment to diagnose, continue with the pathetic replace this part and see what happens concept, or continue from the comfort of my couch on my laptop, eating a bag of chips and watching COPS on my TV in the background! Thank you so much for taking the time to respond.
Friday, August 6th, 2010 AT 10:39 AM