disco300tdi · Oct 4, 2010

hi guys i have a 3.9 v8 auto discovery engine that is in a defender 110 crew cab it has idle issues where it revs up and down when stationary.
I have been told to check the RST but i dont know where to start looking if you guys could help please thanks in advance.
rob

fett · Oct 4, 2010

little box on the chassis rail by the gearbox usually

classic kev · Oct 5, 2010

Unlikely to be the transducer, if it is a hotwire injection system, the transducer only sends a signal to tell the ECU to switch on or off the idle stabilisation. Where your idle is irratic I would suggest starting with cleaning the stepper and plenum, check and set the throttle disc and make sure there are no air leaks on the induction system.

disco300tdi · Oct 5, 2010

hi yea i have cleaned the stepper and the plenum and resealed with hylomar i have checked the air gap and that is fine i now have the problem of not running all 8 cylinders i have just swapped the rotor arm dizzy cap plugs and leads it runs like a bag o ****e at the moment.
next i think i will reset the base idle

fett · Oct 5, 2010

use gen parts and or magnecore leads.

pattern are ****e!

classic kev · Oct 6, 2010

disco300tdi said:
hi yea i have cleaned the stepper and the plenum and resealed with hylomar i have checked the air gap and that is fine i now have the problem of not running all 8 cylinders i have just swapped the rotor arm dizzy cap plugs and leads it runs like a bag o ****e at the moment.
next i think i will reset the base idle

Make sure the HT leads are correctly routed and properly clipped. As Fett said DO NOT USE pattern parts in your ignition system - that means Lucas Cap and Arm and any good quality leads. You might also want to check some other things while you're in there. Are you getting a big fat spark off the king lead?

hammoj28 · Oct 6, 2010

As above, I binned the RST on my 3.9 and it runs fine.

Mr Noisy · Oct 6, 2010

check the ingition timing.

remove all leads and get a spare plug and check each one to make sure there is a spark at each lead.

and yeah, pattern parts are a gamble at best, dingocroft.com famousfour.com do the genuine lucas.

when my road speed transducer has a broken wire inside it, the car ran perfectly but when i slowed down to traffic lights it used to cut out. having said that, the 3.9 doesnt have a speedo cable normally - has it got a cable and RST, or just an electric speed sensor?

if its a speed sensor, does the speedo work too?

disco300tdi · Oct 6, 2010

i am sure it has a speed sensor and the speedo works fine too gotta have a look tomorrow the rotor arm is a **itpart i have just noticed damn

fett · Oct 6, 2010

put that straight in the bin then!

disco300tdi · Oct 6, 2010

yea will order lucas one tomorrow lol

fett · Oct 6, 2010

try and get the silcon coated one, it really makes a differnce on the cold damp mornings!

disco300tdi

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Mr Noisy

Coming in your ears.

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