98deville Posted May 2, 2011 Report Share Posted May 2, 2011 Just scanned the car and got these codes: P0101- mass or volume air flow a circuit range/ performance P0171 - system too lean Bank 1 P0174 - system too lean Bank 2 P0300- Random / multiple cylinder misfire detected What do I need to do to fix these codes? Its a 2003 Cadillac DTS with 109,000 miles. Link to comment Share on other sites More sharing options...
Göran W Posted May 2, 2011 Report Share Posted May 2, 2011 I think you´ll find a defektive MAF-sensor or a leaking vacuumhose connected to the same sensor. Link to comment Share on other sites More sharing options...
Ranger Posted May 3, 2011 Report Share Posted May 3, 2011 Replace the MAF sensor first. Then clear the codes. If the P0171 & P0174 come back, it's probably a rip in the plenum (the rubber coupler between the TB and the manifold). Also clean the TB. Link to comment Share on other sites More sharing options...
98deville Posted May 3, 2011 Author Report Share Posted May 3, 2011 How about the misfire? The car shakes real bad due to this.I already changed the front coil pack and plugs about a yr ago. Should I change the back also? On the maf sensor should I go with an ac delco or does it matter on this? Link to comment Share on other sites More sharing options...
Cadillac Jim Posted May 3, 2011 Report Share Posted May 3, 2011 The lean mixture condition that throws the codes will cause misfires. Fix the lean mixture codes first and the misfire will probably go away. -- 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...
98deville Posted May 3, 2011 Author Report Share Posted May 3, 2011 Just ordered the AC Delco MAF Sensor from rockauto for about $145. Link to comment Share on other sites More sharing options...
PAUL T Posted May 6, 2011 Report Share Posted May 6, 2011 Just ordered the AC Delco MAF Sensor from rockauto for about $145. If that does not do it check for vacuum leaks around the evap system, throttle body, EGR valve. Make sure your air cleaner is installed properly and there is no leaks in air induction system. Also check your intake manifold bolts for tightness, you can get a vacuum leak there also. You should have checked for the vacuum leaks first. I am afraid the MAF sensor was not bad. A leaky FPR can cause these codes also. My 97 manual suggests running down all the other codes before settling on the MAF sensor. Learning to check things out in the correct order can save a bunch of money spent replacing good parts. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted May 6, 2011 Report Share Posted May 6, 2011 Sensors are rarely the cause for a trouble code. Going for the sensor or module is like shooting the messenger. -- 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 7, 2011 Report Share Posted May 7, 2011 It's possible that a leaky FPR might cause the misfire code, but I doubt it would have anything to do with the other three. Link to comment Share on other sites More sharing options...
98deville Posted May 7, 2011 Author Report Share Posted May 7, 2011 just recieved the MAF Sensor and switched it out...and still the same problem, so I switched it back to the old one. I also noticed (with the engine on) as I unplug the maf sensor connector the engine idles real high at about 1500rpms and as I plug it back in the rpms drop down and the car seems like it wants to die out and the whole engine shakes alot.I also hear a loud, what sounds like a vacuum leak coming from the intake manifold. Whats the best way to check for vacuum leaks? Link to comment Share on other sites More sharing options...
JimD Posted May 7, 2011 Report Share Posted May 7, 2011 just recieved the MAF Sensor and switched it out...and still the same problem, so I switched it back to the old one. I also noticed (with the engine on) as I unplug the maf sensor connector the engine idles real high at about 1500rpms and as I plug it back in the rpms drop down and the car seems like it wants to die out and the whole engine shakes alot.I also hear a loud, what sounds like a vacuum leak coming from the intake manifold. Whats the best way to check for vacuum leaks? Your primary issue is certainly a vacuum leak as indicated by the P0171 and P0174 codes you originally posted. Those two codes together on your year engine point to a failed/cracked "plenum" with 99% certainty. Plenum is what GM calls the rubber connection between the throttle body and the intake manifold. As vacuum leak test (which you do not need, the two codes say it all), you can spray some brake-clean solvent at the bottom surface of the plenum. A noticeable change in idle speed will occur. Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
Cadillac Jim Posted May 7, 2011 Report Share Posted May 7, 2011 The simplest thing to do is to check all the hoses that connect to the throttle body. A common problem hose is the one to the PCV because it has oil mist in it that attacks the rubber. Sometimes the gasket or rubber spacer between the throttle body and the intake manifold gets cracks in it. Some people recommend that you use an oil can to detect small leaks because they will just stop when oil gets in them. Yours sounds a bit big for that. As far as the manifold seal is concerned, popping the manifold is easy on an Northstar. The gasket is reusable, but if you have a big leak and it's not a hose, or if you determine that it's the manifold seal against a head, I would get new intake manifold gaskets, take the intake manifold off, clean everything up (no abrasives!!!) and put on new gaskets. -- 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...
98deville Posted May 11, 2011 Author Report Share Posted May 11, 2011 just recieved the MAF Sensor and switched it out...and still the same problem, so I switched it back to the old one. I also noticed (with the engine on) as I unplug the maf sensor connector the engine idles real high at about 1500rpms and as I plug it back in the rpms drop down and the car seems like it wants to die out and the whole engine shakes alot.I also hear a loud, what sounds like a vacuum leak coming from the intake manifold. Whats the best way to check for vacuum leaks? Your primary issue is certainly a vacuum leak as indicated by the P0171 and P0174 codes you originally posted. Those two codes together on your year engine point to a failed/cracked "plenum" with 99% certainty. Plenum is what GM calls the rubber connection between the throttle body and the intake manifold. As vacuum leak test (which you do not need, the two codes say it all), you can spray some brake-clean solvent at the bottom surface of the plenum. A noticeable change in idle speed will occur. Problem fixed, The whole bottom of the old Plenum was torn apart. Bought me another one from the dealer for about $35. Thanks guys Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.