Maintenance....

[CTX-SLPR]

Well all 3 of my cars have the check engine light on. The Riviera I'm not really worried about since there are other things I want to fix and it's nothing that worries me. However my DD Lincoln LS and Silverado do worry me. The LS just has a single code telling me that cat performance is off on one bank. I'm interpretting this to mean that the rear O2 sensor needs to changed. Since it's coming up on 100K miles I was thinking of putting all 4 in there but I don't want to throw money at a non existant problem.

Should I put the fronts on and see if it goes away then change the one that's associated with the code if it doesn't? At $80 a pop I don't want to be changing more than I need too.

On the Silverado the most annoying thing is the ABS intermittently tripping the LF wheel sensor. Since it's not a constant fault and I've cleaned and reseated the connection, am I just doomed for a new wheel hub since it looks like it's integrated? The other codes seem to be related to what might be a leaking intake gasket as people have suggested since when cold it idle surges, the fuel trims are way out, and there is definately some idle instability even when it's warm outside. I really just want the lights to go out since I'm going to be trading it in sometime in the near future.

Thanks,

[oldsman71]

I guess there isnt a way to test a O)2 senser?


when I was in auto tech in witchita, a guy with a monte carlo ss DRILLED threw his check engine light when he couldnt
get it to go out .... note this was in 1989!!!! he got an F in diagnostics, a rich kid who had mom and dad pay to fix his car

[TheSilverBuick]

On the Lincoln, why not suspect that the cat is actually under performing at 100k?

Interesting thing I noticed about my '07 Silverado today, I don't think it has ABS. Driving on ice and snow, the pedal doesn't do the ABS thing and no motor's whirring. I haven't popped the hood, but I don't recall seeing an ABS light, light up when I start the truck either...

[TC]

Bad Cat Performance means the cat is going bad, you need to replace it, the rear O2 can also be bad, I'd start with replacing that and see if the code comes back, if it does you need a new cat.......And just so you know the rear O2 is only there to monitor the cat it has nothing to do with monitoring the AFR's other than to tell the computer to richen up the mixture to cool the cat down.....

As for changing all the O2's it's not a bad Idea with that type of mileage, I do it on my cars just as a preventive maintenance thing.....

And yes you'll probably have to replace the hub, but check the wiring and connections first...... as for the other code it'd be nice to know what it is, but if you feel it's vacuum check for vacuum leaks, you can spray carb clean around the intake and see if the idle changes.......Do it along where the intake gasket is if you feel that is where it is leaking....

[DanStokes]

Cats are WAY tougher than people think they are. We (EPA) did tests on in-service cars (borrowed from private citizens who used them in their daily lives) with up to 200K miles and they were still working well. Not to say they CAN'T go bad, of course. I had to replace the one on the Dakota at about 90K miles because the bed (AKA "brick") had broken up, maybe the result of excessive trailer towing. When you banged on it it would rattle.

I agree that O2 sensors are prone to failure around 100 K although all of ours are OK so far (2 on the Dak @ 125K, 4 on ME's HHR @ 99.5K) (knock on wood).


Dan

[Bamfster]

I'm gonna say CAT on the LS. I've been chasing the same thing on the wife's Pathfinder and it has finally started rattling.

Had an 04 Suburban in last fall. Wonky cold idle more often than not and constant surges when warm. Fuel trims were all over the place ... Spidey pointed me to a TSB that addressed it with R&Ring intake gaskets. It took care of all of the issues ....

[hauen]

If you think it's the sensor you can always pull them, clean them, and then swap sides and see if it still throws a code. It probably will, I had the same problem on my LS around 120k. It was the cat.

I'm no help when it comes to GM products, however.

[CTX-SLPR]

Thanks for the idea Hauen... unfortunately it does look like it's the cat because after a big fight to get the second sensor out and swapped sides, clearing the DTC then going for a 45min drive I still have P0430, Catalyst Efficiency (Bank 2). Now that I think about it I remember hearing a rattling sound off and on that I thought was from a heatsheild but the cats are in the right place to be the source. CRAP... ~$700 for an OEM cat and I'm not sure I'd trust the $215 rockauto units. The O2 sensors are built right into the cat so a DIY setup wouldn't really be something I'd like to tackle.

[TC]

Thanks for the idea Hauen... unfortunately it does look like it's the cat because after a big fight to get the second sensor out and swapped sides, clearing the DTC then going for a 45min drive I still have P0430, Catalyst Efficiency (Bank 2). Now that I think about it I remember hearing a rattling sound off and on that I thought was from a heatsheild but the cats are in the right place to be the source. CRAP... ~$700 for an OEM cat and I'm not sure I'd trust the $215 rockauto units. The O2 sensors are built right into the cat so a DIY setup wouldn't really be something I'd like to tackle.

Looks like Summit has you covered with a bolt in unit under $200.........

http://www.summitracing.com/search/Part-Type/Catalytic-Converters/Make/CHEVROLET/Model/IMPALA/Engine-Type/V8/Year/1996/Converter-Inlet-Attachment/Stock-flange/?Ns=Rank%7cAsc

[stangbanger]

Magnaflow makes a nicely priced bolt in cat for most vehicles. I have used them on three different vehicles and have had no issues what so ever in 50k+ miles on all of them.

http://www.magnaflow.com/02catalytic_converters/02product/shopdisplayproducts.asp?portal=49%20State&make=LINCOLN&model=LS&year=2000

There are the part numbers. wasn't sure of the year or motor you had for the Lincoln. My advice would be to find the model # on there, and purchase from www.hottexhaust.com I have used them for all of the Magnaflow products I've purchased and they are the cheapest I've found and iirc still offer free shipping.

[CTX-SLPR]

Magnaflow makes a nicely priced bolt in cat for most vehicles. I have used them on three different vehicles and have had no issues what so ever in 50k+ miles on all of them.

http://www.magnaflow.com/02catalytic_converters/02product/shopdisplayproducts.asp?portal=49%20State&make=LINCOLN&model=LS&year=2000

There are the part numbers. wasn't sure of the year or motor you had for the Lincoln. My advice would be to find the model # on there, and purchase from www.hottexhaust.com I have used them for all of the Magnaflow products I've purchased and they are the cheapest I've found and iirc still offer free shipping.

Thanks for the info! I had pretty much come to the conclusion that a Magnaflow was what I was going to buy. The only question really left is do I get the cheaper Direct Fit system or, and I haven't priced it out yet, get a universal OEM grade cat and have a muffler shop splice it into the piping potentially on both sides. Unlike the truck, I plan on keeping this car for years so I'd like to put parts are on it that will last for another 100K ish miles.

I'll price out the options tonight

[Stich496]

if your keeping it.. direct fit.. it'll save ya down the line. unless you're next exhaust is gonna be custom and not off the shelf

[stangbanger]

Mine last one was cheaper to have a universal fit welded in, than a direct fit. I also replaced the flex pipe (yes the car drives the wrong wheels) with a universal as well. $150 versus $350 for direct fit cat and factory flexpipe.

[SpiderGearsMan]

Bad Cat Performance means the cat is going bad, you need to replace it, the rear O2 can also be bad, I'd start with replacing that and see if the code comes back, if it does you need a new cat.......And just so you know the rear O2 is only there to monitor the cat it has nothing to do with monitoring the AFR's other than to tell the computer to richen up the mixture to cool the cat down.....

As for changing all the O2's it's not a bad Idea with that type of mileage, I do it on my cars just as a preventive maintenance thing.....

And yes you'll probably have to replace the hub, but check the wiring and connections first...... as for the other code it'd be nice to know what it is, but if you feel it's vacuum check for vacuum leaks, you can spray carb clean around the intake and see if the idle changes.......Do it along where the intake gasket is if you feel that is where it is leaking....

right tc , never saw a p0420 repaired with o2 sensor
green intake gaskets are the hot setup

[CTX-SLPR]

Got a Magnaflow 23937 D/S cat for $443.79 thanks to the military discount! It should be here next week so next weekend I can crawl under there and see if this is an in the garage or at the hobby shop on the lift type of job. When the paycheck drops I'll need to pick up a pair of front O2 sensors and 6 coil clips from rock auto so I can get to fixing most of the car's little faults atleast engine wise. We'll see how long I wait to order up all 4 shocks and a seat back that's broken a clip.

The truck I need to check the codes again and see if they are a return of the same stuff and order up that intake gasket. The ABS will have to wait till the new year.