JimD Posted December 2, 2006 Report Share Posted December 2, 2006 Would one of our Cadillac owners test this for us and report your findings? To check for a restricted catalytic converter, connect a vacuum gauge to the intake manifold then hold the engine speed to about 2,000 rpm. If the vacuum gradually drops, there is a restriction in the exhaust system. It could be in the cat, but it could also be due to a collapsed pipe or rusted out muffler. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 2, 2006 Report Share Posted December 2, 2006 Do you want me to do this and report the vacuum readings for you? 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...
JimD Posted December 2, 2006 Author Report Share Posted December 2, 2006 No, Mike. Unless you know for sure your exhaust system is partially plugged up. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 2, 2006 Report Share Posted December 2, 2006 OK that's what I thought, too bad I didn't run this test when my wife's CAT was clogged (02 Monte Carlo) 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...
Cadillac Jim Posted December 2, 2006 Report Share Posted December 2, 2006 Is there a way to get the MAP sensor data on the DIC to do this test? -- 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...
sal.carceller@cox.net Posted January 23, 2007 Report Share Posted January 23, 2007 I currently have what I suspect is a clogged Catalytic Converter in my 93 Seville 4.9L. The Converter has been rattling for 2 months or so and now the rattle has stopped but I have no power at 1/2 to full throttle range with severe power loss/ misfires at WOT. I will test the procedure outlined above for Vacuum in the intake and report the results. Another method of testing for exhaust back pressure is to remove the O2 sensor (before the Cat) and put a low pressure gauge into the fitting (use 0-10lb gauge) also be sure to use long hose (3 feet or so) this hose length allows for the exhaust to slightly cool before reaching the gauge. At idle you should see less than 2lbs pressure here, then at 2500RPM you should still see less than 2lbs if you see readings around 4lbs or more you have a restriction in the exhaust, most likely the cat but not always. Sometimes you could have a clogged/ crimped pipe. Or the cat internally fell apart and these broken parts went down the pipe toward the mufflers, so you may wish to also test back pressure futher down stream by drilling small hole in pipe before the muffler and testing with gauge at that spot. The easiest thing is to take the cat out and look inside it to see what's up. Hope this other test method helps. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted January 23, 2007 Report Share Posted January 23, 2007 Put a fork in the cat. It's done. If you let it go too long, pieces of the ceramic get in the mufflers and you need to replace them too. -- 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...
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