engine overevving on tickover

[Archangel]

just lately i getthe occasionly i get overevving on tickover .

What do you think it mght be ? (2.1 litre engine), hopefully not expense apart from this it runs fine 800 rpm steady

[marty1979]

Could be a few things, but it's a good idea to check the green coolant sensor and it's plug, the one that lives in the side of the cylinder head on the passenger side as you're looking at the engine. Infact, it's a good idea to check all the plugs you can get your hands on cause they are all to easily attacked by nastiness.

[Archangel]

Could be a few things, but it's a good idea to check the green coolant sensor and it's plug, the one that lives in the side of the cylinder head on the passenger side as you're looking at the engine. Infact, it's a good idea to check all the plugs you can get your hands on cause they are all to easily attacked by nastiness.

I`ll check it but just done 240 mile trip and temp was between 70/80 the whole way . What is the significance of the coolant sensor ?

[marty1979]

There are 3 sensors relating to temperature on the 2.1. The blue one next to the fuel filter is for the temp gauge, the brown one next to it controls the cooling fans, and the green one on the side of the cylinder head is used by the ECU to control fueling. From my experience, this green one has been the cause of this revving issue, but as I say there are many sensors, including a metering sensor inside of the pump itself which is a real problem if this is the culprit. There are also 2 electrovalves under the black cover on top of the injector pump that can cause issues. To be honest it would be a good idea to get it on a Lexia with someone who can read the live data, that way all sensor parameters can be seen. It may even be something as simple as air ingress. Can you clarify the revving, how high up does it go?

[Archangel]

There are 3 sensors relating to temperature on the 2.1. The blue one next to the fuel filter is for the temp gauge, the brown one next to it controls the cooling fans, and the green one on the side of the cylinder head is used by the ECU to control fueling. From my experience, this green one has been the cause of this revving issue, but as I say there are many sensors, including a metering sensor inside of the pump itself which is a real problem if this is the culprit. There are also 2 electrovalves under the black cover on top of the injector pump that can cause issues. To be honest it would be a good idea to get it on a Lexia with someone who can read the live data, that way all sensor parameters can be seen. It may even be something as simple as air ingress. Can you clarify the revving, how high up does it go?

doesnt go beyond 3000 revs, but a hard rev seems to settle it down