lightflood Posted February 3, 2009 Report Share Posted February 3, 2009 Hello gentlemen, I have used this site for help years ago on my 93 STS, that car is still going strong at 150k. This car is my brothers 2000 deville 110 k mi. It has a dead miss at all engine speeds on the #4 cylinder. The codes are: p0101, p0171,p0174, p0304. Changed the plugs----no luck. I'm thinking bad coil. Possibly the rubber boot is torn to account for the p0171 and p0174, but I get no rpm change when I soked it with carb cleaner. Any thoughts? thanks guys Link to comment Share on other sites More sharing options...
BodybyFisher Posted February 3, 2009 Report Share Posted February 3, 2009 Take your email address out of your profile it might cause you to get spam. Where did you get these codes from the on-board diag or a code scanner? I am surprised to see a specific P0304 P0101 - Mass Air Flow (MAF) Sensor Performance P0171 - Fuel Trim System Lean Bank 1 P0174 - Fuel Trim System Lean Bank 2 P0304 - Cylinder 4 Misfire Detected The 2000 may have that rubber intake plenum you speak about, it usually gets a crack in it causing the P0171 and P0174 codes. Check out cylinder #4 for a bad plug, coil pack, injector and compression Check the electrical connector on your MAF and take a look at the sensor end (small wire) it to see if its covered with oil, grease or dirt, you can buy MAF cleaner. Does this car have an aftermarket air filter (read K&N). BE careful with the MAF don't damage the wire You can get your codes here in the future http://myweb.accessus.net/~090/dtcobd2.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...
BodybyFisher Posted February 3, 2009 Report Share Posted February 3, 2009 By the way Here is a photo of the rubber plenum in question, it connects the throttle body to the intake manifold. It cracks on the bottom and I don't think the carb cleaner will get there, use the extension 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...
lightflood Posted February 3, 2009 Author Report Share Posted February 3, 2009 I got the codes from a code scanner. I just solved the misfire issue. I took loose the suspect coil pack and laid it on top of the engine. I attatched a lead to the ground of the pack, the other end to the head. Then I took some old plug wires from a 6.0 chevy and cut the boots back on the end which normally goes over the coils. So I was pushing spark backward through them, (they didn't seem to mind). Then I could pull the wire out of the #4 hole to see that the spark was VERY weak. Then to be totally sure I switched the module out from the other bank. I had the same problem so that ruled out the module. I'm going to go to car-part.com and find a used coil pack, run the car and see if any of the other codes reappear. Thanks guys Link to comment Share on other sites More sharing options...
lightflood Posted February 3, 2009 Author Report Share Posted February 3, 2009 Oh and I said it wrong, it an eldorado not a deville. But I guess their the same as far as this is concerned. Link to comment Share on other sites More sharing options...
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