Hello, I have a 2006 Envoy Denali that has been giving me problems lately. It stalled while driving two and a half weeks ago, leaving my friend and I stranded in the middle of the street. The truck would crank and crank but it wouldn't start. I decided to get out and grab my tools so that I could disconnect the battery and hopefully clear any sensors that were causing me problems. Well, I couldn't have picked a more terrible time to open my liftgate and lean for my tools... A drunk driver plowed into the back of my truck at 40 mph. Luckily, my buddy saw him coming and yelled at me about 3 seconds before impact. I looked over my shoulder and jumped as he struck my leg then the rear of my truck. I landed on his hood with a sore leg, but greatful to be alive! Anyways, the next day at the tow company's yard, the truck fired right up. It was fine for a week and then started acting up. It stalled at a friend's house and wouldn't start for two days. Finally, it started and ran fine for a couple of days. Then, it started mising occasionally while driving. The RPMs would completely drop down to zero and if I pumped the pedal, sometimes they would kick back up to over 1,000 and the truck would stay running. This all mainly happened while I was going about 55mph. Other times, it would just stall completely and I would be forced to shift it into neutral and start it back up. For some reason, when I was moving, it seemed like I could get it to start again. Then it ran fine for a few more days, no problems at all. It wouldn't start again at the end of last week for a whole day. I got it to start and it ran for one day. I was driving home and going about 25 mph and it suddenly stalled. No warning or anything. I coasted to a stop and tried to start it but nothing. I had to get it towed home. It's been sitting in my driveway ever since. I've been trying everything I can think of. I put a fuel pressure gauge on the fuel rail and verified that the gauge jumps to 60psi when the key is turned and then settles to about 58psi. I've checked for any codes and the only ones I was able to pull were while it was running like crap and it stalled so I threw the code reader on it before starting it back up while driving. I ended up getting two codes: P1133-Heated oxygen sensor insufficient switching bank 1 sensor 1, and P1153-Heated oxygen sensor insufficient switching bank 2 sensor 1. I have not gotten these again, and was wondering if I got these because of it running rough and stalling or if they are a symptom of the problem. I checked the throttle body to make sure the butterfly wasn't getting stuck as some members have reported and all was well. I took it off and cleaned it while I was at it. Then, I decided that since I had checked fuel and air, I would check spark. I pulled a plug and cranked the motor and didn't get any spark. i put the plug back in and decided to replace the crankshaft sensor since i had read that it would cause the motor to crank and crank, but wouldn't give me any spark. Nothing changed. I had replaced the ignition switch since i also read about those doing crazy things and just wanted to rule out the cheaper and easier culprits. I grabbed my test light and checked for voltage to the coils. I'm getting voltage to the coils as well as the reference from the PCM. However, I'm not getting any ground. I read a wiring diagram that says the coils are grounded to G109 on the left side of the motor. I could not locate any such ground and I looked very thoroughly. My diagrams and pictures show the ground being in the same sheath as the knock sensor and then continuing above the sensor where it should be bolted into the engine. There is no bolt, no wire, and no indication of a ground having been there. Any chance the diagram i have is wrong? I have followed the ground cables from the coils to the underhood fuse box and I don't know where they go from there. I really want to get this thing started! Any suggestions? I'm wondering if the PCM has something to do with it or if that is unlikely since I'm getting voltage and reference ground at the coils from the PCM?
Thanks in advance!
Kyle
Thanks in advance!
Kyle