I have a 1999 GRand Cherokee that I have had at the shop for a couple month, and the couple things the tech did was replace the crank sensor to restore spart to the motor, but after that he commented that he was able to get it started but it was miss firing and back firing. so he used some kind of scope to check some thing out. He checked the cam sensor said that was ok. At this point I am not sure why the vehicle will not start...any suggestions would be very appreciative. thanks again.

Note: I have replaced the ECU with a salvage yard unit, due to the techs recomendation, I also replaced the engine wire harness due to a couple broken connectors on the old one, that is all I have replaced under the hood.

 

Take a look at this article, I thought it was pretty interesting.

http://www.askamechanic.info/askamec...ent/view/36/47

 

So did he change the timing chain or does the timing need to be corrected?