hello all, i have a 2000 disco with 125k, within past couple weeks it has posted two coeds; P0440 an P0555. I replaced the purge valve and no SES light since. What I am still experiencing is a elevated rough idle in park around 950 rpm with ac on, when in drive the rpm drops to about 700 but with what feels like a misfire that gets progressively worse. When vehicle is cold it does not have this issue. Its only with the ac on that its noticeable, and no SES light. other wise drives normal and fuel mileage seems to be about the same.

no loss of coolant or oil, has had new plugs and wires with last year.


any ideas?

thank you!

 

I'd start with Vacuum leaks. Your P0440 and P0555 are evap system and brake booster sensor I think. Brake boosters run on vacuum and vacuum leaks can lead to bad idle. I would check the hose from the booster to the intake, the servo with the red circle, if your 2000 has this. From there check the MAF, and anything looking like a black tube or hose. Listen for leaks, etc.