I have a 2001 Cadilliac Deville and here is what happens, it sounds funny when it idles, When you first start it when it's cold and after it runs for 30 secounds, the rpms slow down to normal idle speed and then it sounds like the rpm's are raising and droping like 200 rpms over and over again but I am not sure why it's doing this. I am a sevice tech but don't know what to do here.
2007-01-23 16:15:01 · 5 answers · asked by stealth5033 3 in Cars & Transportation ➔ Maintenance & Repairs
I am not sure which is which, but I think your car's computer operates on different circuits when it is cold and warm. One is closed loop and the other is open loop. I think the closed loop is for cold start operation. I sound like it is fluctuation between closed and open loop. you Can change the cycles with a pretty sophisticated code reader. Then it could also be the O2 sensor, Map sensor, or throttle position sensor hunting the correct RPM for cold operation. Good luck.
2007-01-23 16:38:45 · answer #1 · answered by gyro-nut64 3 · 0⤊ 0⤋
There is a good chance that the A/C clutch is cycling. When the PCM sees that the clutch is engaged, it adds a bit of time to the injectors. When the clutch disengages, the PCM takes the time away. If the refrigerant is a bit low, but high enough t allow the system to work, the "rolling idle" occurs.
Just a thought.
Happy Motoring
2007-01-23 16:33:18 · answer #2 · answered by Ironhand 6 · 0⤊ 0⤋
hi, we'd hint demanding to discover leaks on prototype autos utilising propane. i do no longer could desire to be flamed in this because it does artwork and acceptable completed isn't risky. Hook up a tach to the motor and positioned a protracted tube over the splendid of a propane torch. Crack the valve purely a tad till you get a tiny circulate of propane. Now come across a vacuum line and pull it off the motor. Introduce the top of the hose to the disconnect vacuum port and be conscious the rpm earnings on the tach. Reinstall the vacuum hose. Now start up finding the motor, intake manifold and vacuum lines interior the engine compartment. once you hit the leak, the rpm will advance. you are able to living house in on the offending section right this moment. do no longer forget the interior below the sprint which has a lot of vacuum plumbing. it works in this too. sturdy luck Phil
2016-11-26 22:33:11 · answer #3 · answered by Anonymous · 0⤊ 0⤋
i own a repair shop,and you need to check for a vacuum leak some where on it,that will cause it to do this,,and also a bad set of plugs will make it idle funny,the computer can compensate the fuel and spark timing on it ,but it cant increase the amount of the spark,and a bad plug or plus,can cause this,really when it comes down to it there's about 10 actual things that can cause this,if you have it scanned you probably will get a trouble code from it,good luck,i hope this help,s.
2007-01-23 16:31:40 · answer #4 · answered by dodge man 7 · 0⤊ 0⤋
you're a service tech for what? Dell?
It could be a throttle position sensor or an air flow meter problem or something as simple as a leaking vacuum hose. Also make sure you aren't too low on oil or coolant.
2007-01-23 16:28:20 · answer #5 · answered by sk33t3r 3 · 0⤊ 0⤋