How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15201
Experience:  GM Grand Master Technician 2007. 14 years experience.
Type Your Chevy Question Here...
GM Tech (Cam) is online now
A new question is answered every 9 seconds

2007 Chevy 2500 HD. 6.0L. I have a dead miss on cylinder 7.

Customer Question

2007 Chevy 2500 HD. 6.0L. I have a dead miss on cylinder 7. I have checked compression, spark, injector pulse, injector, spark plug, valves, and springs. Everything checks good. I even did a smoke test and can not find a leak. Any suggestions.
Submitted: 1 year ago.
Category: Chevy
Customer: replied 1 year ago.
Is this one to difficult to get a response?
Expert:  Ryan Schott replied 1 year ago.
Run it with the valve cover off and watch your rockers you could have flattened a cam lobe. Also swap the plug with another if the porcelain cracks too far in it can be difficult to see. If you don't find anything there do a leak down on that cylinder. Have you monitored fuel pressure to see that it doesn't bleed down when the key is off?
Customer: replied 1 year ago.
Have already taken the valve cover off and check the valves for proper movement. And fuel pressure is correct and no leak down.
Expert:  Ryan Schott replied 1 year ago.
have you pulled and cleaned inside your fuel rail, contaminants will build up on the ends and restrict fuel injectors, can you shoot me your vin
Expert:  Ryan Schott replied 1 year ago.
did you watch your valves while it was running or were you just tuning it by hand?
Customer: replied 1 year ago.
Activated the injector and verified fuel pressure drop.
Customer: replied 1 year ago.
Not running. Cranking
Customer: replied 1 year ago.
Will send vin tomorrow.
Customer: replied 1 year ago.
Expert:  Ryan Schott replied 1 year ago.
Does it have active fuel management?
Expert:  Ryan Schott replied 1 year ago.
Either way I would run it while monitoring that misfire and watch those rockers, you can rubber snub the coils over towards the booster for room. If nothing can be seen while the misfire is present and vehicle running, then its time to go back to step one, see if your spark is good and you can pull a large gap with it, if you can access an AFIT it will give a more accurate injector test, redo a leak down at a range of pressures, recheck compression and compare it to several other cylinders. If you go back through all of this and there is still no problem found you might need to try and measure the lift from your rockers or remove the head and visually inspect the cam and lifters.
Expert:  Ryan Schott replied 1 year ago.
I have seen a few with bad lifters and a slightly machined down cam because of it, you will get normal enough compression and it won't leak however the slightly insufficient valve opening will cause your miss.
Customer: replied 1 year ago.
Ok I will let you know my findings.
Customer: replied 1 year ago.
Turned out to have a faulty injector. Sprayed in a stream instead of a spray pattern.