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Dr.Carz, ASE Certified Technician
Category: Cadillac
Satisfied Customers: 303
Experience:  12 years of exp. 10 with ford on my third with all other makes.Just love cars
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Rough and irratic idle on my cadillac DHS 2004
, When

Customer Question

Customer: rough and irratic idle on my cadillac DHS 2004
JA: Thanks. Can you give me any more details about your issue?
Customer: When started, it drops idle to around 500 rpm and idles roughly. Pushing gas pedal might increase rpm to 900. After awhile, it will accelerate, but still idles roughly around 500 rpm
JA: OK got it. Last thing — JustAnswer charges a fee (generally around $18) to post your type of question to Cadillac Experts (you only pay if satisfied). There are a couple customers ahead of you. We can help you for less if you're not in a rush. Are you willing to wait a bit?
Customer: sure i can wait. I was planning to first lubricate the throttle assembly
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Submitted: 1 year ago.
Category: Cadillac
Expert:  Dr.Carz replied 1 year ago.

Good evening. I would like to say not to lubricate the throttle body. Instead service it by using throttle body cleaner and a nylon brush (Old toothbrush works great). This is a drive by wire system that over time carbon builds up and restricts airflow. Remove the air inlet tube and I use the same screw driver to hold open the throttle plate and spray with cleaner top bottom sides then scrub down with the brush respray and re scrub repeat as necessary. I then start the car and hold rpm at 2500rpm with someone else's foot or pry bar and run the rest of the can through the intake while running and well ventilated area. Good luck and keep me posted.

Customer: replied 1 year ago.
Chad, I thoroughly cleaned the throttle assembly with carb cleaner. Did not fix the problem. Idle drops down to 500 rpm then very rough idle. Seems like a control/vacuum issue or possible an O2 sensor, but I'm not a mechanic (I am a mechanical engineer). Anything else to try?
Expert:  Dr.Carz replied 1 year ago.

Vacuum leak will be next I use some brake cleaner or some left over cleaner from throttle body with engine running start spraying around the intake area looking for an rpm change. The pcv line to the valve cover are known to crack over time but the upper intake will need to be removed not a bad job to remove if needed. Is there a check engine light on yet?

Customer: replied 1 year ago.
Chad, I just dropped it off with the auto mechanic. I'll let a professional fix it. I'm sure you guys have seen this a hundred times. Thanks, Frank
Expert:  Dr.Carz replied 1 year ago.

Smart move if you are not comfortable with the repair then let someone else do it. I have been at this for 20yrs and fix everything. For time sake I sent my wife's car to Volvo for the timing belt and cam gear replacement. That is what they see and work on and glad I did saved me 230 dollars for the tools that I have not yet needed and 6 hrs of my time. I did not have to learn on the bosses car. Keep me posted and please feel free for further input. Also remember to rate my services and Accept Thank you. Will be fairly simple repair just remember it is your car and you have the right to see your parts and decline any work been a lot of poor news on here lately from people getting taken advantage of.

Expert:  Dr.Carz replied 1 year ago.

Please remember to rate my services and Accept Thank You.As always any further assistance with this topic is open to you. Thanks again.