Rough idle - discovery 1

hi_arshard · Oct 31, 2024

Hello guys, good day …!

I am having an issue with idle. The RPM goes up and down. In cold start By Default the RPM idle on 900 to 1100 RPM. When stopped in traffic or signal light the RPM goes up and down and the engine stalls. when the car comes to a complete stop on Gear D this happens. In neutral the idle is up and down for 1800 and down to 600RPM but it doesn’t stall the engine.

Only last change done was replaced the vacuum advance unit on the distributor.

Appreciate your support on this as usual.

Rangieman123 · Oct 31, 2024

Check your throttle position sensor. If it doesn't correctly tell the ECU when your throttle valve is closed it won't activate the idle control valve.

discool · Nov 2, 2024

Simples first, so remove the crankcase breather (flame trap) and its hose to the plenum chamber and soak in petrol to clean it, then refit,

If you still have an issue carefully remove the throttle control valve and clean and replace and then check the base idle which was set in the factory, info on the procedure and how to do that is in workshop manuals.

There’s not much you can do with the throttle position sensor, its just a variable resistor, so don’t fiddle with it as they are now obsolete… so you will have to find a replacement or make a replacement item

hi_arshard · Nov 3, 2024

discool said:
Simples first, so remove the crankcase breather (flame trap) and its hose to the plenum chamber and soak in petrol to clean it, then refit,

If you still have an issue carefully remove the throttle control valve and clean and replace and then check the base idle which was set in the factory, info on the procedure and how to do that is in workshop manuals.

There’s not much you can do with the throttle position sensor, its just a variable resistor, so don’t fiddle with it as they are now obsolete… so you will have to find a replacement or make a replacement item

1 month the go I cleaned the flame trap.

I checked the the rover gauge the TPS is working and responding when the physical acceleration.
But I see very less response from the stepper motor (bypass control valve) I am suspecting this. But the issue happens only after driving few KM’s told start no problem or stop the car for few minutes and start driving back no issue unless you for for few Km’s. Issue: as you slow down / stop on idle , it starts idling erratically and which god down between 500 and 1500 RPM and the car stalls

Rough idle - discovery 1

hi_arshard

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Rangieman123

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discool

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hi_arshard

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