I recently shot the spark pulg from the 6th cylinder of my 2002 mercury cougar 2.5 liter DOHC engine. I got all new plugs and wires an put a helicoil on the 6th cylinder so the plug would stay in. about a day later the engine started showing loss of power and when i stoped at stoplights the car would shudder constantly in idle. Going up hills and off the start the car shudders up till bout 30 mph then jets off, acceleration is tough because i have to slam the gas to the floor to get it to go. The engine light says cylinder 6 misfire an i went to shops around here they keep telling me the helicoil came loose and i have to get the header re-milled but i9ts gonna cost me a buttload of cash to take the header out. What should i do? could it be possibly anything other than the helicoil?
The repair will take removing the head and replacing it most likely.
Could try never seize thread coating
SOURCE: 99 cougar v6 P0352 misfire cylinder 3 and 4 replaced igntn coil..
Had the same problem, car was misfiring on cylinder 3 and 4. replaced wires, plugs, and ignition coil. still misfired on the same cynlinders. turned out the main engine wiring harness plug in was coming loose. spent well over $150 on the unneccesary repairs and ultimately fixed the problem wit a $3 bag of wire ties to hold the plug in...
SOURCE: I have a misfire on cylinder 4.
It sounds like your car is having intermittent misfires as it is only happening under load. This is really hard to diagnose based on a description.
You could be getting a bad air/fuel mixture, bad wiring, bad rings, oil or coolant leak into the engine, etc...
Scan the car with an OBD tool to see what the code is as that will help narrow down the cause.
SOURCE: i have a 2001 mercury cougar with the 2.5L v6
Its time to do a injector balance and cylinder leakage test, to determine whether the injector or its circuitry is bad . The leakage test will tell you if the cylinder has a compression leak.
SOURCE: I mixed up the fireing spark plug cables on my 6
On the 2002 Mercury Cougar
For the 2.5L V6 DOHC:
Firing Order:
1-2-3-4-5-6
Cylinders:
.....(back)
1......2......3
4......5......6
.....(front)
Ignition Coil:
.(back)
4...6...5
3...2...1
.(front)
1995 Mazda MX-6
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