WHAT ARE THE KNOCK SENSOR AND THE SPEED SENSOR.l HAVE A RENAULT ESPACE WHICH l AM CURRENTLY HAVING PROBLEMS WITH, IT WON'T START WHEN ENGINE IS WARM.

If it wo not start when the engines warm it could be the cold air sensor wherever that may be on that car. It is telling the brain that the car is cold even when it is warm and therefore the mixture is wrong and makes it a pig to start

There isnt much difference in the spark except for the resistance of the H T leads. Your problem is likely that the mixture is over rich when starting from cold as the result of a sensor problem

The spark is generated at the coil. To get to the plug it travels through spark plug wires and the spark plug itself. The wires and the spark plugs have a high internal resistance which reduces the spark intensity.
Check out the web site below.

Its the same spark but ur plug leads may be resistive.


The knock sensor is a device bolted usually to the cylinder block that is used to detect when there is detonation going on in the engine cylinders. Detonation (put simply) is when parts of the fuel / air mix combust prematurely in the cylinder for various reasons u do not need to know. Its bad because it can blow holes in ur pistons.

One way of reducing detonation is to use a signal from a knock sensor to retard the ignition timing (done via the engine ECU). It allows the ignition timing to be as advanced as is safe or indeed mapped to be. If the knock sensor fails, it is likely that ur engine ECU will default to a safe ignition map to get u home.

A speed sensor - It may refer to an engine speed sensor- usually a hall effect (magnetic) pick up on the engine flywheel that feeds engine speed & and timing signals to the engine ECU.

You can live without a knock sensor but can be stuffed without a speed sensor.

In any event be assured that ur car is probably much more unreliable than most given its make. Best buy a Honda or Toyota, some of which r made in the UK.

In my experience its hard to find anyone in the garage trade who really knows about engine management systems let alone afford the stupid prices for diagnostic equipment. If u find one, do not let them go.

And finally (sorry for rambling - its me age) there could be many reasons for ur hot starting problems - try renault forums, there may be a well known ongoing issue that causes it.