This is a continuation of the thread I started about a month ago: http://www.discoweb.org/forums/showthread.php?t=66486
Quick synopsis of previous events:
Ok. So after this I decided to replace the plugs (again) and wires. I replaced the NGKs (only ~2500 miles on them) with the champion coppers, and replaced the wires with magnacore 7mm. Now the idle was still rough and it was making a ticking/grinding sound from the front of the engine. Long story short dealership replaced bad A/C compressor, power steering pump, and alternator belt. Now purrs like a kitten. The engine has never idled so quiet or smooth and drives like a dream. About 50 miles of driving after bringing it home from the dealership the CEL pops up, I pull the code and sure enough it is the cyl 7 misfire code. Now it still idles drives fine. I have NO symptoms of a misfire other than the stupid orange light on my dash.
I don't know where to go from here. I assume if it was a coil pack more than just the #7 cyl would be misfiring. My next route is fuel system. I am going to seafoam the sh!t out of this thing. I am going to run a half bottle through the intake and a whole bottle in the gas. If that doesn't do it I am going to drive it until is catastrophically fails. I just spent $1900 last week I am not dumping anymore money into this thing. I am not going to throw money at it trying to diagnose this problem ie: replacing the coils, taking off the head looking at the valves, etc. Especially since it drives fine and I am basically treating a light on my dash board. And the bad news is the dealership got us a rental while it was in the shop. They got us a new Tahoe and my wife loves it. I have not even told her about this problem yet. She already wants to get rid of the disco and get a tahoe now. If this continues it might seal the disco's fate.
Quick synopsis of previous events:
This code has popped up twice in the past 1.5-2 months. First poppped up and I did a general tune up (BTW 105k miles). Air filter, plugs (NGK nothing fancy), cleaned MAF sensor, seafoam, and cleaned throttle body. Also at the time checked out the wires(looked ok to me) I even ran it in the dark looking for any arcing and nothing, ran some seafoam through the intake and gas. Code went away after a couple days. About 1.5-2 months later the code popped up again this week. The engine runs fine, power good, idles a little rough, acceleration is good, runs smooth, avg gas mileage. I always run premium gas, I buy brand name gas. And I always run a fuel system treatment every3-5k miles.
Ok. So after this I decided to replace the plugs (again) and wires. I replaced the NGKs (only ~2500 miles on them) with the champion coppers, and replaced the wires with magnacore 7mm. Now the idle was still rough and it was making a ticking/grinding sound from the front of the engine. Long story short dealership replaced bad A/C compressor, power steering pump, and alternator belt. Now purrs like a kitten. The engine has never idled so quiet or smooth and drives like a dream. About 50 miles of driving after bringing it home from the dealership the CEL pops up, I pull the code and sure enough it is the cyl 7 misfire code. Now it still idles drives fine. I have NO symptoms of a misfire other than the stupid orange light on my dash.
I don't know where to go from here. I assume if it was a coil pack more than just the #7 cyl would be misfiring. My next route is fuel system. I am going to seafoam the sh!t out of this thing. I am going to run a half bottle through the intake and a whole bottle in the gas. If that doesn't do it I am going to drive it until is catastrophically fails. I just spent $1900 last week I am not dumping anymore money into this thing. I am not going to throw money at it trying to diagnose this problem ie: replacing the coils, taking off the head looking at the valves, etc. Especially since it drives fine and I am basically treating a light on my dash board. And the bad news is the dealership got us a rental while it was in the shop. They got us a new Tahoe and my wife loves it. I have not even told her about this problem yet. She already wants to get rid of the disco and get a tahoe now. If this continues it might seal the disco's fate.
Last edited: