probably the governor going bad
There could be many reasons, a vacuum leak is one possibility.
Could be many reasons such as contaminated fuel (water), could be in need of a tune up, could be a large vacuum leak,
This is very normal. The extra drag on the engine caused by the alternator and the a/c causes the engine to slow. The engine speed is most likely then compensated by the e.c.u to a pre-set value, thus causing the revs to rise.
A bad coolant temperature sensor is one thing that could cause an idling speed problem with a Peugeot 406. There could also be a problem with the idle control valve.
The power steering pump is working hard and the engine is only idling. It could be the harmonic balancer
too much fuel (unburned) getting into the exhaust. could be your oxygen sensor or catalyst converter. less likely, a leaking fuel injector
Could be,in need of a tune up, a vacuum leak, contaminated fuel (water), If we knew what year, make, model and engine more info would be available.
why is my ford sport trac run rough at idling. Being that the check engine light is on, start with having the codes read. Your local auto parts store can help with that at no cost.
It could be major or minor. You will have to have the codes read to know possible causes.
It could, you need to have the codes checked to know possible causes.
Mass Air Flow MAF sensor could be your, problem check that!
there are a number of things this could be, for example. vaccum problem, timing and firing problem, fuel problem, and if the check engine light is on it could be a nubmber of sensors, example, tps, iac, so you just have to start somewhere and go with it from there checking to find out what it really is