Rough Idling

QUENCY GARDNER

MEMBER
2001 CHRYSLER TOWN AND COUNTRY
3.8L
6 CYL
2WD
129,000 MILES

My vehicle has a rough idle. Spark plugs and wires replaced. Check engine light indicates the map sensor problem. Purchased new map sensor and problem persist. Obtained another map sensor and no change in idle condition. I am not sure if the following is related, but the power brakes acts as if they are not power brakes, about half the time. Replaced the master cylinder and the unit behind the master cylinder which controls the vacuum flow. Yet no change in the function of the power brakes. What could possibly be the problem?

2 Replies

CARADIODOC

MECHANIC
33,873 POSTS

You could have saved a lot of time and money by having this properly diagnosed. The MAP sensor measures intake manifold vacuum, and apparently is indicating a problem with that vacuum. The power brake booster runs on intake manifold vacuum. If it is not working, you do not replace the part. You find the cause of the low or missing vacuum.

Those comments are not meant to insult your intelligence. They are only to show how too many people get "wrapped around the axle" and make things too complicated. The first thing you must understand is diagnostic fault codes never say to replace parts or that one is bad. When a part is referenced in a fault code, it is actually the cause of that code only about half of the time. Your mechanic will check for wiring and connector terminal problems, and perform some other tests before spending money on a part. Also, there are over a dozen fault codes related to the MAP sensor, and they mean very different things. You need to list the exact code number before I can suggest a course of action. Given the multiple symptoms, I would start by suspecting a pretty large vacuum leak.