95SevilleSLS Posted May 28, 2007 Report Share Posted May 28, 2007 Any ideas why my 02 Seville STS would be getting about 4-5 less MPG on the highway than my 97 Seville STS? I would think that the 02, which is actually rated for better fuel economy, would get higher. Thanks for the help in advance! -Dusty- - 02 Seville STS, white diamond - 93 Sixty Special, Tan with vinyl top - 79 Coupe DeVille, Tan with Tan top - 06 GMC Sierra Z71, Black - 92 Silverado C1500, black and grey - 83 Chevy K10 Silverado, Black and Grey Link to comment Share on other sites More sharing options...
OynxSTS Posted May 28, 2007 Report Share Posted May 28, 2007 2002 was not a very good year for Catalytic converters at GM... Plugged cat = bad mileage Easin' down the highway in a new Cadillac, I had a fine fox in front, I had three more in the back ZZTOP, I'm Bad I'm Nationwide Greg Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 28, 2007 Report Share Posted May 28, 2007 2002 was not a very good year for Catalytic converters at GM... Plugged cat = bad mileage That is so true Greg, my wife's 02 Monte Carlo needed its CAT replaced at 50K and the dealer stated its common...for 02 Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
KHE Posted May 28, 2007 Report Share Posted May 28, 2007 '02 White STS, You may want to have your catalytic converter checked - considering your posts on poor fuel economy posts, I think it is worth looking into. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
95SevilleSLS Posted May 29, 2007 Author Report Share Posted May 29, 2007 I was thinking it may be a cat, because my 97 seems to accelerate a little better than the 02 also. How or who can I have check the cat? How much are they usually? -Dusty- - 02 Seville STS, white diamond - 93 Sixty Special, Tan with vinyl top - 79 Coupe DeVille, Tan with Tan top - 06 GMC Sierra Z71, Black - 92 Silverado C1500, black and grey - 83 Chevy K10 Silverado, Black and Grey Link to comment Share on other sites More sharing options...
Ranger Posted May 29, 2007 Report Share Posted May 29, 2007 It may still be under warranty. Emissions are warrantied longer by law. I forget the time/mileage, but someone will chime in with it. EDIT: Just looked it up. It's 80/80,000. Link to comment Share on other sites More sharing options...
BodybyFisher Posted May 29, 2007 Report Share Posted May 29, 2007 Consider buying one of these Exhaust Back Pressure Testers http://www.mytoolstore.com/toolaid/diagn04.html Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
95SevilleSLS Posted May 29, 2007 Author Report Share Posted May 29, 2007 I bought it with 80,500 miles so that warranty went up right when I bought it. I may buy that pressure tester to see if that's the problem. -Dusty- - 02 Seville STS, white diamond - 93 Sixty Special, Tan with vinyl top - 79 Coupe DeVille, Tan with Tan top - 06 GMC Sierra Z71, Black - 92 Silverado C1500, black and grey - 83 Chevy K10 Silverado, Black and Grey Link to comment Share on other sites More sharing options...
daniel812 Posted May 30, 2007 Report Share Posted May 30, 2007 emission warranty is 8 year/80k miles. A partially clogged catalytic converter may also be the cause for your slight stumble/hesitation at idle. Link to comment Share on other sites More sharing options...
95SevilleSLS Posted May 30, 2007 Author Report Share Posted May 30, 2007 emission warranty is 8 year/80k miles. A partially clogged catalytic converter may also be the cause for your slight stumble/hesitation at idle. Hmmm, that would be nice to cure everything at once. Sucks that they are so much. -Dusty- - 02 Seville STS, white diamond - 93 Sixty Special, Tan with vinyl top - 79 Coupe DeVille, Tan with Tan top - 06 GMC Sierra Z71, Black - 92 Silverado C1500, black and grey - 83 Chevy K10 Silverado, Black and Grey Link to comment Share on other sites More sharing options...
Cadillac Jim Posted May 30, 2007 Report Share Posted May 30, 2007 You can change your catalytic converter yourself. If you get a made-to-fit one online the cost is $150-$300. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
95SevilleSLS Posted May 30, 2007 Author Report Share Posted May 30, 2007 Where did you find one that cheap (inexpensive I suppose is the correct word)? The only one I found was about $330. I'm not worried about the installation costs, I have a guy I go to who would probably charge $20 at the most. -Dusty- - 02 Seville STS, white diamond - 93 Sixty Special, Tan with vinyl top - 79 Coupe DeVille, Tan with Tan top - 06 GMC Sierra Z71, Black - 92 Silverado C1500, black and grey - 83 Chevy K10 Silverado, Black and Grey Link to comment Share on other sites More sharing options...
Cadillac Jim Posted May 30, 2007 Report Share Posted May 30, 2007 I went through an exhaust system exercise last Fall when I was rear-ended, the main casualty being my mufflers and tips, and did a lot of web searching. In this process I discovered that my old cat was clogged from running too long with head gasket leakage. I went with a high-flow, welding-required solution for abut $80 and had it installed for another $80. The muffler shop used my old flanges and oxygen sensor fittings; that saves a lot of money. Looking at my stored links... Rock Auto has a Merit, welding required, for $93, Direct Fit (little or no welding) for $182: http://www.rockauto.com/catalog/raframecatalog.php Xtrme Flow offers a wide range; CA direct-fit are high, though: http://www.xtremeflow.com/catalyticconverters.htm Parts Train sells a selection of direct-fit and universal, including the high-flow that I went with (part 94009): http://www2.partstrain.com/products/Engine...OURING-001.html -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
Ranger Posted May 30, 2007 Report Share Posted May 30, 2007 It may still be under warranty. Emissions are warrantied longer by law. I forget the time/mileage, but someone will chime in with it. EDIT: Just looked it up. It's 80/80,000. OOPS. Make that 8/80,000 Link to comment Share on other sites More sharing options...
95SevilleSLS Posted May 30, 2007 Author Report Share Posted May 30, 2007 It may still be under warranty. Emissions are warrantied longer by law. I forget the time/mileage, but someone will chime in with it. EDIT: Just looked it up. It's 80/80,000. OOPS. Make that 8/80,000 That would be one heck of a warranty! -Dusty- - 02 Seville STS, white diamond - 93 Sixty Special, Tan with vinyl top - 79 Coupe DeVille, Tan with Tan top - 06 GMC Sierra Z71, Black - 92 Silverado C1500, black and grey - 83 Chevy K10 Silverado, Black and Grey Link to comment Share on other sites More sharing options...
tjtjwdad Posted May 30, 2007 Report Share Posted May 30, 2007 It may still be under warranty. Emissions are warrantied longer by law. I forget the time/mileage, but someone will chime in with it. EDIT: Just looked it up. It's 80/80,000. OOPS. Make that 8/80,000 That would be one heck of a warranty! Hmmm, Mine is getting near 80K, maybe a once over before the warranty expires. Link to comment Share on other sites More sharing options...
bweekes Posted June 1, 2007 Report Share Posted June 1, 2007 Mine failed at ~55K last fall. The dealer said GM went with a different manufacturer in 02 for their converters which have been failing left and right. The dealer also said that GM chose a different company soon after... I hope I have better luck with my new one but I've got the new warranty w/ anyway. Link to comment Share on other sites More sharing options...
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