Solved the Problem with my 2002

I finally solved the problem with my 02 LeSabre. :iceslolan:iceslolan I posted several times over the last year about this car misfiring and then not starting for a day or 3 after parking it. It just happened last week and then started and I have been driving it since with no problems. I had the fuel pressure (42psi) checked and the only code that came up was the infamous P0420. Emisions Catlyst ect. ect.... Yesterday, as I was getting to my driveway the car started to misfire again and sputter when under load. I pulled it in my yard and popped the hood to take a looksee. There right next to the coil packs was a visible spark/short. The wires, when I replaced them last, were all kinds bunched together with some of the boots actually touching. :cwm27: Here's the stranger part, :sunglasse there was moisture/water seeping from the edges of the boots. :uhoh: The only logical explanation here was condensation. This has happened on mostly damp days but in no way was I driving through puddles or anything to cause excess water to cover the engine. Now, yesterday was below freezing here but around 25 degrees, which would be ideal for condensation. :iceslolan After further investigation, this would also cause the code P0420 but, like a moron I went and changed my oxygen sensor (bank 1) today and I'm waiting to see if the light goes off or if I need to have this cleared. I hope this helps at least one other person here and at the very least my dash lights will stay off until my inspection next month. :rofl::rofl::rofl:

Rob

Rain likes to roll from the windshield, onto cowl, and divert onto your engine.
Clean your cowl, and check the rubber gasket when the hood is closed.
I like to park my car up hill for better drainage.

The down stream HO2 sensor told the ECU, that the catalytic converter is bad on bank 1.

Changed the O2 sensor and cleared the codes. 2 days later the F'in light is on again. So if it's not the wires shorting out and it's not Bank #1 02 sensor. What the FFFFFFFFFF is it ??? match and lighter fluid here I come.

Rob

How is this car running other than the DTC P0420?
The original HO2 sensor is probably good. I would use the new HO2 sensor upstream, use the original down stream, and have a back pressure test done on your catalytic converter.

Perhaps the misfire dumped a lot of unburned fuel into the exhaust and constantly overloaded the catalyst. It's likely you destroyed the catalytic converter by allowing the misfire condition to persist for so long. I know I had a similar situation crop up with my 1992 where it had a stumble and misfire for a very long time and eventually just obliterated the catalytic converter. Partially burned fuel will leave moon craters in the catalyic converter catalyst honey comb. I would try to pull the exhaust apart and take a look at the converter itself. The exhaust on this car is not difficult to disassemble and you can get a really good look at the catalyst with a flashlight in the front pipe. I've done the same repair on my 2000 with the exact same symptoms although my catalyst failed on the 2000 without any misfire present. I junked the 1992 before fixing the catalyst and misfire problem.


Now I've got to scramble through the forums to see if I can get a handle on why my transmission has blown up on my 2004. My 1992 LeSabre died with 240k on the clock. My 2000 and 2004 barely made it to 110 without major problems. Car quality around the world has just taken a total nose dive, I think during the roaring 90's people decided they'd just rather throw the car away when it got to 100k. Car companies picked up on that and pumped all the profit margin into gadgets and creature comforts and figured the car would last 100k. Now that I'm facing down the great recession I need another 240k car, what I have is a disposable 2004. Sorry you're having a tough time, we're all in the same boat. I finally got a 3 month contract job with decent pay and I'm going to rack up my credit cards again to pay for a 2400k transmission so I can get to a job that ends in six weeks. It's interesting that 1/3 of my check goes to washington DC, if I had that money to pay off my damn bills I'd be in fine shape right now.

Cat efficiency can only be checked with a graphing scanner comparing pre and post cat 02 readings, or use a non contact thermometer and check the inlet vs outlet cat temps, when fully warmed up a good cat will have outlet temps at least 100 degrees higher than the inlet temp.

I think I paid 450 for the whole exhaust, cat and all at the dealer on the 2000. I'd also put the job in the range of easy to slightly annoying. If you are certain you solved the misfire problem, maybe you should just replace the whole exhaust and be done with it. By the time you get done running the diag and buying O2 sensors, you might end up worse off financially. At least you already have one new sensor. All you need is one more and the exhaust and you're virtually gaurunteed to have the catalyst issue solved. I'd be more concerned about making sure the misfire is gone.

I should mention that I solved a serious misfire problem with my 2004 recently and it turned out to be the ignition module itself, not the coil pack, not the plug, not the wire, fuel pressure regulator, or any of the usual suspects. I ended up diagnosing the problem by using an old school inline spark tester which showed me that I had no spark on one of the cylinders at the time of the misfire. If you can get the car to repeatedly misfire at startup you could easily pull the wires and insert the inline tester one at a time. Fortunately for me, my misfire was constant and totally consistent, I was able to start and stop the engine as much as I needed in order to diagnose.


I'd also check to be sure you are pushing the spark plug wire boots all the way down on the coil towers. Sometimes they seem to click down when in fact they are only partially engaged.

I replaced all the plugs and wires yesterday, after finding shorts in two of the 6. I originally replaced them with some cheap wires and you get what you pay for. I'm hoping the cat isn't fried. I don't think it was that bad because my gas mileage wan't effected and the exhaust didn't smell rich. Time will tell and I will have code cleared or wait to see if light goes off. Thanks to all.

Rob

Also, I had the ignition module checked and it was fine.