Dominator Posted December 14, 2010 Report Share Posted December 14, 2010 Recently my wife was complaning that her care (2000 Seville) was stumbling on idle and acceleration. Knowing how to check her codes she came up with a code 300 on the pcm which is an engine misfire. I drove the car last night with the same results and the check engine light was flashing as I was driving. I have started the car a few times after this occurance and this morning it would not start at all. The air temp was 9 degrees and of course the combination of the problem and air temps make life miserable. My question is, would changing out the plugs be a good first step in a possible repair or would I be better off having it towed for a full diagnostic? Link to comment Share on other sites More sharing options...
MAC Posted December 15, 2010 Report Share Posted December 15, 2010 The P0300 code means there is a multiple misfire, which is two or more cylinders. Take a look at the plugs. Replacing plugs can solve the problem. However, other culprits could be a vacuum leak or even low fuel pressure or bad battery. Low fuel pressure can be caused by a clogged fuel filter. Check for leaking vacuum by simply listening for a leak or even it has been suggested to spray some carburetor cleaner around the intake manifold. If the engine idle changes then you have a leak. If you haven't changed the fuel filter in a while or ever, then change it first because it's cheap and an easy job. Then turn to the spark plugs unless you hear an obvious vacuum leak. Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 15, 2010 Report Share Posted December 15, 2010 The problem with posting in MULTIPLE places is that it gets answered all over and members dont see that happening. ONLY post in one location here is a link to your other post on the same problem http://caddyinfo.ipbhost.com/index.php?showtopic=34763&st=0&p=179732&fromsearch=1entry179732 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...
Ranger Posted December 15, 2010 Report Share Posted December 15, 2010 A flashing SES light actually means "severe" misfire detected. You might want to change the boots along with the plugs just in case there is some carbon tracking on them. Link to comment Share on other sites More sharing options...
Logan Posted December 16, 2010 Report Share Posted December 16, 2010 A flashing SES lamp with PO300 is a misfire bad enough to damage the catalytic converter. The FED warranty on a cat is 8 year/ 80K. A 2000 model would be out of warranty. Some cars will display a different code for whichever cylinder is missing. PO301 would be misfire cylinder #1, PO302 would be misfire cylinder #2...etc. The 2000 Deville will only display a PO300. It's up to you to figure out which cylinder is misfiring. A Tech 2 will easily show which cylinder is misfiring. On that version Northstar. There is a silver painted and a black coil pack available. The silver one is designed for the front bank of the engine. That said..they are interchangeable. I carry a spare one in my trunk. Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 16, 2010 Report Share Posted December 16, 2010 Very cool Logan, I had referred this member to your prior experience in this thread http://caddyinfo.ipbhost.com/index.php?showtopic=34763&st=0&p=179732&fromsearch=1entry179732 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...
Dominator Posted December 16, 2010 Author Report Share Posted December 16, 2010 A flashing SES lamp with PO300 is a misfire bad enough to damage the catalytic converter. The FED warranty on a cat is 8 year/ 80K. A 2000 model would be out of warranty. Some cars will display a different code for whichever cylinder is missing. PO301 would be misfire cylinder #1, PO302 would be misfire cylinder #2...etc. The 2000 Deville will only display a PO300. It's up to you to figure out which cylinder is misfiring. A Tech 2 will easily show which cylinder is misfiring. On that version Northstar. There is a silver painted and a black coil pack available. The silver one is designed for the front bank of the engine. That said..they are interchangeable. I carry a spare one in my trunk. Link to comment Share on other sites More sharing options...
Dominator Posted December 16, 2010 Author Report Share Posted December 16, 2010 Really appreciate the advise. After changing out the plugs it still would not start. It appears that the coils pack or packs are suspect here. I can't think of anything else which would cause multiple cylinders not to fire. Any further thoughts? Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 16, 2010 Report Share Posted December 16, 2010 Really appreciate the advise. After changing out the plugs it still would not start. It appears that the coils pack or packs are suspect here. I can't think of anything else which would cause multiple cylinders not to fire. Any further thoughts? As logan noted you need to determine which bank is not firing, get one of these. As it gets colder, resistance increases. Its probably the entire bank is out, that would probably cause a no start. If you can find on of these gadgets you can quickly determine which bank is out http://www.waekon.co...copvsintro.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...
CarlaValentine Posted December 17, 2010 Report Share Posted December 17, 2010 Would a crankshaft position sensor set a code on this car? Judging by the symptoms, particularly the no start, I would think that COULD be a possibility. Link to comment Share on other sites More sharing options...
BodybyFisher Posted December 17, 2010 Report Share Posted December 17, 2010 Would a crankshaft position sensor set a code on this car? Judging by the symptoms, particularly the no start, I would think that COULD be a possibility. Carla, on an OBD2 system a crank sensor should set a code I personally focused on the P0300 and the fact that this year with its coil packs tend to have them go bad 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...
Ranger Posted December 18, 2010 Report Share Posted December 18, 2010 As BBF said, a CKP sensor SHOULD set a code, but they don't always do it. Link to comment Share on other sites More sharing options...
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