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Discussion Starter #1 (Edited)
Hello

I have a 2002 Park Avenue with 122k miles. (Not SC) A few weeks ago, it started hesitating and stumbling under load; accelerating 25-40 mph, going uphill. No codes.

I replaced:

1. the plugs and wires. (Napa "wired for life" and iridium plugs)
2. TPS (throttle pos. sensor)
3. Fuel filter

Drove it up a steep hill, started sputtering, coughing and the service engine light came on, flashing and alarm chiming. The light and alarm went away when I let up off the throttle, but now there's a pending code for mis-fire on #3.

Since the plugs and wires are new, I used my old inductive timing light on the #3 wire - sure enough it was skipping. So I got a new coil for that pair. According to my timing light, problem is still there on #3, perhaps even worse.

I checked the other wires, and sure enough, there were skips/misses on all of them, but #3 seems worse than the rest, and that's with a new coil.

I have read about the crankshaft sensor and ICM possibly being the problem, and according to that, if the sensor was bad it wouldn't run at all. Is this true?

Also, can the ICM fail progressively, but still let the engine run, but poorly?

Thank you in advance for any advice you can send my way!

---------------update-------------

So I bought an ICM from a scrapyard - came with the coils. Swapped out the ICM, left my coils in, and if anything, it's worse. Used inductive timing light on all six wires - looks like the 4 wires from the lower and middle coils are firing at the right tempo with the occasional miss, but the 2 wires from the top coil are firing about half tempo, so those 2 are missing every other stroke, pretty consistently. I am going to replace the (cheap O'reilley's) new upper coil with the junkyard one and see what effect that may have.

-------------update #2-----------

So I put the junkyard coil in replacing the new one - performance improved, a bit better than when I started. I put all 3 junkyard coils in, but have the same symptoms. It will run OK between 1-2k rpm, but when I open the throttle a bit more, it tries to accelerate, gets a bit above 3k rpm, and skips and stumbles and stays in a low gear. if I back off the throttle, it will upshift, and I can nurse it along as long as I feather the throttle and stay below 2k rpm. What am I missing here? BTW, my scanner now shows "no codes" so the previous P0303 is now gone. WTF?
 
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