Several days ago my truck started to miss. I had a hunch it was some plug wires that were in bad shape. I replaced the plug wires, dist. cap and spark plugs. The truck would not start, labored the started and would backfire. I of course thought I had botched the firing order. After checking the firing order (18436572) I adjusted the dist. to try and find a position that would at least allow the engine to start and idle.
After many attempts I grabbed the timing light, disconnected the injectors and set the timing to 0-deg. TDC and tried again, no luck. Removed the spark plug wires one at a time to try and isolate a bad plug or wire, still no luck. Set engine to TDC and checked position of rotor, pointing nearly to number one plug on dist. cap.
At this point I ran a compression check and got readings between 75 and 90 lbs. on each cylinder. Referring to my rebuild manual I see no reading below 101 lbs. in min. allowable compression. Decided that maybe the timing chain had jumped and removed cover. Timing marks are correct.
I'm out of ideas. Any thing that would cause a miss in the engine, and a complete backfire after new plugs, cap, rotor and wires were installed? I was also unaware that this model truck had an ESC that needed to be disconnected before setting the timing. So after I re-install the timing cover, I'll probable go ahead and just replace the chain and sprockets as long as I'm this far, I'll try and unplug the ESC and try again. I'm also not sure if this is an acceptable reading for compression. I replaced the heads on this engine about 3-5k mi. ago.
After many attempts I grabbed the timing light, disconnected the injectors and set the timing to 0-deg. TDC and tried again, no luck. Removed the spark plug wires one at a time to try and isolate a bad plug or wire, still no luck. Set engine to TDC and checked position of rotor, pointing nearly to number one plug on dist. cap.
At this point I ran a compression check and got readings between 75 and 90 lbs. on each cylinder. Referring to my rebuild manual I see no reading below 101 lbs. in min. allowable compression. Decided that maybe the timing chain had jumped and removed cover. Timing marks are correct.
I'm out of ideas. Any thing that would cause a miss in the engine, and a complete backfire after new plugs, cap, rotor and wires were installed? I was also unaware that this model truck had an ESC that needed to be disconnected before setting the timing. So after I re-install the timing cover, I'll probable go ahead and just replace the chain and sprockets as long as I'm this far, I'll try and unplug the ESC and try again. I'm also not sure if this is an acceptable reading for compression. I replaced the heads on this engine about 3-5k mi. ago.
May 12, 2011 at 12:57 AM
