Join Date: Mar 2011
Location: Fort Loramie, Ohio
Random misfire with 2.7
My 2002 Intrepid (120,000 miles) 2.7 has had a random misfire for a couple years now. Typically it'll happen when the engine is cold , but not always. Pretty much a perpetual check engine light. Here are the different scenarios that show up.
1. About 10% of the times that we leave the house in the morning, pull onto the highway, push down normally on the gas and the engine bogs down and you can't get any speed at all. Let off the gas a couple times and punch it down and suddenly the engine comes to life and all is good.
2. Engine seems to be running fine going down the road, but when you pull up to a stop light, it feels like the engine is running on two cylinders (shakes). Put the car in neutral and the shaking seems to go away. (This isn't a real common occurrence, maybe once a week)
3. Traveling down the highway on cruise at 65mph, everything works fine for quite a while and sullenly you can feel engine hesitations, which go away and repeat themselves until you take it off cruise and punch the gas to the floor.
All these conditions have flashing check engine lights, beeps, associated with them. The Dodge dealer says that it only shows (random misfire). I have a code reader coming next week, so I'll be able to keep a closer eye on it after that.
Some things that have been done to the car up to this point are a new fuel pump, new spark plugs, new coil wires. Throttle body cleaned.
This morning, the engine was running rough so I tried pulling coil power to isolate which cylinder was causing the problem. The front two cylinders (1 and 4) made no difference at all to engine performance. All other cylinders made a big difference when I pulled the power to the coil. I tried a new coil on one of the problem cylinders and it made no difference at all. I checked the compression of the questionable cylinders and it seemed good (about 175 lbs). I then decided to only plug in coils of the questionable cylinders to see if there was any reaction if I tried to start the engine. To my surprise, the engine started on those two cylinders. I hooked up the rest of the coils and now when I tried to remove a coil power to cylinders 1 and 4, I can hear the engine dropping rpms. (This is the random part of the problem that is making the diagnosis so hard)
A Dodge dealer has had the car twice and an independent repairman once.
Any ideas as to what could be causing this? Like I said, I'll have a code reader in a few days, so I'll be able to tell you what is being reported by the computer.
Thanks in advance,
Fort Loramie, Ohio