96 V8 Disco Idle speed

[LandyV8]

How do I increase the idle speed on my 96 3.9 v8 Discovery? From cold it is fine but when the engine is warm it struggles to idle and cuts out.

Any ideas?

[Jon v8]

The engine ecu controls the idle speed,so something is wrong.Have a good look around all the vacuum hoses on the engine plus the large inlet hose,make sure they are all leak free.Any exhaust manifold leaks will cause problems too.A sticky idle stepper motor will also do this plus failed oxygen sensors.

[landnut]

Hi all,

thanks, that's interesting! as we are having similar problems on our disco 1 with LPG, ( with duff ECU). Have had problems since mechanic bypassed/disconnected LPG system assuming we would pay 600€ for new one a.s.a.p! two years on still a problem. We assume this is causing a vacuum problem, as we have checked vacuum pipes.
We have booked her in for ecu check (and for tune up) in Limoges france hoping it will solve the problem. Any thoughts would be appreciated ta!

Out of interest what is a sticky stepper motor? :rolleyes: Oxygene senser we assume you mean air mass meter?

[JulesV8]

The iddle is set at the factory and I would be inclined to leave it alone as it cant change (screw is threalocked)

As said, I would first make sure that the engine is breathing properly. I had a similar problem on my 96 V8 and its amazing what a new air filter will do. Check your Ht leads and plugs, always worth replacing anything suspect.

The Stepper motor is different to the Mass airflow meter. The idle air system or stepper motor can get clogged up and sometimes needs a clean. Its located at the back of the plenum, so as you are looking at the engine, head down the left hand side behind the alloy thing with 3.9L stamped on it.

What you are looking for is a connection with 2 allen bolts at the top, a vaccum hose running to it and an electrical multiplupg. Take the rubber hose off and give it a clean - see if that makes any difference.

Good luck

[v8jobster]

agree with Jules, have you also checked your plugs recently, had a problem on mine, was fine cold, but when up to temperature, it missed fired as plug no 7 was breaking down. Then you might start the great debate, as to what plugs are best, champion, bosch, ngk!!:D