View Full Version : Help!! Engine idling with hiccups

06-24-09, 07:16 AM
Engine started idling poorly especially once warmed like its missing. Not throwing any codes,I've changed front bank of plugs ( the back ones seem next to impossible),used Sea Foam, cleaned throttle body, What next? I've read something about a plennum failure causing a vaccuum leak. Could this be it? What about injectors? Don't want the garage to be hunting and pecking like I do on the keyboard.

06-24-09, 07:18 AM
I forgot to mention this is a 2003 DTS with 80,000 miles.

06-24-09, 10:58 AM
Read the thread down in Cadillac Technical Discussion, Technical Tips, titled "How to pull codes on '98 -'04..........." and then write them all down, go to the the link with OBD-II in the URL and decipher what each code means - also whether each code is a Current or History. You don't need a scanner - it's all built into the car already.

To check the intake manifold plenum, remove the engine cover, start the engine, and shoot a tad of choke cleaner at the base of the hose clamp between the throttlebody and intake manifold. An idle speed change is a vacuum leak. That rubber bellows tends to crack from heat and oil vapor attack and then causes a nagging vacuum leak which will set O2 sensor codes eventually.

06-24-09, 11:56 AM
I knew how to do this on my 97 Deville but I'm lost with this one. Where exactly is this thread you speak of? Thanks.

06-24-09, 12:17 PM
Go down to the bottom of this page where you see Cadillac Forum Jump. Click the arrow and when the drop down box opens, scroll down to TECH TIPS forum. See the sticky at the top of the page.

06-24-09, 12:33 PM
Thanks, I'll try this tonight or tommorrow after work. Hopefully, something will show up.