My old OTC Genisys scan tool would be a nice help for you right now. It had a mode where I could monitor individual cylinder misfire counts real time, even if they were not high enough to trigger a diagnostic code. The '98 SHO I had would misfire enough that I could feel it, but never set a code. I was able to track down the offending coils with the Genisys and it found them every time.

If you're really convinced it's a misfire, you could try disconnecting 1 coil at a time to see if you can find one that doesn't seem to have much impact on the way the car runs. When/if you do, you've likely found your offending cylinder. Then check compression on that cylinder, see if the spark plug is wet with fuel. If the compression is good, you might try swapping the spark plug with another cylinder and the coil with yet a different cylinder, then repeat the test of disconnecting one coil at a time to see if the misfire remains on cylinder or follows the plug or coil.

Hi Rod,

So I replaced the battery. It was dead. Odd thing is car is still running the same but since removing the battery cleared the engine codes, no codes have come back. I've driven it for about 100 miles. I'm totally stuck for ideas but it's really irritating to drive. Another thing that has recently started that probably isn't related but worth mentioning, a high pitched whirring sound (sounds like it's coming from the fan) when driving. It changes pitch with acceleration and continues for a second or so after turning off the car. You have any other ideas? It still feels like a cylinder misfire to me, having had bad coils before.

I cannot think of any way the clockspring could cause the car to run funny. Going back to the battery, how old is the battery? Before changing the 3 year old Napa battery in my wife's car, I load tested it with a 100A load and checked the conductance of the battery. Both suggested the battery was "good" but with all the electronics in a modern luxury car, "good" is not always good enough. The first time I ran in to this was on a 1997 Olds Aurora. Two places said the battery was fine, yet it wouldn't even crank the engine over if the headlights were on (which they came on automatically when dark). With a voltmeter on the battery when turning the key to start, we could see the voltage drop below 10 volts. Installed a new battery with no other changes and the car worked fine for the next 2 years he owned the car.

-Rod

Battery Checked out okay. Any chance that clock spring code could cause it to run funny?

How old is the battery? My wife's 2002 LS would stall just about every time she backed out of the driveway the first drive of the day and shifted to Drive. There were no diagnostic codes and everything seemed fine. I finally replaced the battery and never had another issue with the stalling. Her battery was only 3 years old at the time.

Hi Rod. Having a strange LS issue I was hoping you could shed some light on. 2000 V6. I've had to replace ignition coils multiple times. Just started misfiring again but I'm getting no misfire code. I'm 99% sure it's a coil issue but with no code it's weird. The codes I'm getting are 1. P1565 - (I know the Clockspring is bad so I'm guessing that's causing this one) and 2. P0401 (I replaced the EGR Valve and am still getting this code so I have no idea what this one is from.) Do you have any thoughts on this issue?