'98 LC very rough running, engine light flashing

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LCtygrys

LCtygrys

10 Year 15 Year
Joined
May 2, 2007
Threads
21
Messages
92
Location
Pittsburgh, PA,
She was running perfectly for ten years and when I went to start it today it felt like I was missing a cylinder and the engine light was flashing. The light would go off sometimes for short periods of time but the running is terrible at all rpms. I was really low on gas so got a half a tank of Sunoco hi test in in case it was from cheaper gas. Still the same problem. It was really sudden. So I am reading about coil packs? Any others have this happen?

Thanks!
 
I agree with Trunk Monkey. Just pleeease promise me you WILL NOT drive it with the engine light flashing (assuming it's possible to get it into drive in the first place). When your engine light stays on, it's saying you need to check on it the next chance you get but there's no crisis. When the light is flashing, it's your engines way of begging for mercy. Doing so will only result in causing more damage than you even knew was possible.


Official Jeep Recovery Vehicle
 
It starts fine and goes into gear fine. Just scanned it an got a misfire on #7 code. Mechanic will look at it first thing tomorrow. Is there a file here on the procedure for changing the coil packs? I want to go in and see if anything is loose or obvious (plugs, wires etc.) before I take it down.
BTW TF, the light is on steady for now but I still am trying not to drive it except to take it the mile to the shop tomorrow.

thanks
 
The light will stay steady letting you know about the coil pack issue. Start driving it in limp mode and floor it, you'll get the flashing light back.

You could DL the 2004 FSM and look at the coil pack info in there, may not be the exact year as your truck, but the coil pack stuff will be the same.
 
Ok I pulled the coil easily as you might have guessed. I hear there is way to meter it to check it. Anyone familiar with this?
If I can pick one up today perhaps I'll save myself a trip to the mechanic tomorrow.
 
Replace the coil pack. As you've discovered its dead easy to do, and you have the code telling you that the #7 coil has failed.
Buy the Denso from Amazon. Some [most?] after market coil packs are junk. Better still, buy two coil packs and a decent OBDII scanner on Amazon. You'll be all set the next time one fails [and there WILL be a next time] and this will still cost less than your mechanic will charge to replace one coil pack.
 
Thanks APKhaos. We needed to try to get it on the road today so were forced to buy one at Advance Auto, which was obviously not a Denso. I'll be picking a couple of those up from ebay. BTW replacing the coil did nothing for the problem. Would I need to reset the ECM with the scanner for the new coil to work right? I haven't been able to do that yet. So it's off to the mechanic first thing in the morning...
 
LCtygrys said:
Thanks APKhaos. BTW replacing the coil did nothing for the problem. Would I need to reset the ECM with the scanner for the new coil to work right? I haven't been able to do that yet. So it's off to the mechanic first thing in the morning...
Click to expand...

Bad coil pack out, new coil pack in, you're done. You will need an OBD scanner to reset the CEL, but the engine should be smooth once the bad coil pack is replaced.

Aside from the the CEL, is the engine idling smoothly after replacing the coil pack? If not, its also just possible that the aftermarket coil is faulty. Need to read the codes to figure out what is happening now. Have your local FLAPS read codes with their scanner. Most do this as a free service. When coil packs start to fail its possible that another one has died, but unlikely.
 
You can also discon the battery or pull the EFI fuse to reset the CEL. A few have reported the code showing one coil when it's turned out to be another one (or two).

Pick up one of these:
http://www.amazon.com/dp/B004B7YXOM/?tag=ihco-20

If $8 is too rich, they drop down to $5 all the time. If you have a smartphone with Bluetooth, you can read and clear codes with it. Great thing to throw in the glove or tool box.
 
Just a thought, but sometimes when a coil goes bad all that fuel will foul the plugs. If you have a chance to look at it before it goes to the mechanic then pull the coil and plug out. If its covered in fuel a new plug may be needed.
 
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