Mud-club
Vehicle & Technical => Discovery => Topic started by: diesel-smoke on January 23, 2013, 19:43:45
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So, I have got rid of the diesel, and bought a 3.9 petrol in a 1995 discovery, and generally the xar is great, but does have a couple of issues.
When the car is at normal temperature, it runs great, idles at about 650rpm, and pulls like a train, doesn't cut out or overheat.
However when starting, either hot or cold, the engine seems to rev to about 2000rpm, and then gradually drops back to about 750rpm over about 60 - 90 seconds, if you try and drive it straight away, it stutters, and powrr drops off a little, almost as if it is trying to stall, and when you pull up at a junction, the engine is trying to rev at about 1500 rpm.
This lasts for about ten minutes, after every start.
It also stinks of petrol, and at the moment is doing about 5mpg, on petrol and gas. (Same thing happens on either fuel),.
Like I said, when warmed up it is great, but still heavy on fuel.
It has recently had, new plugs, leads, coil, ign amp, dis cap and arm, idle valve, air flow meter, and throttle position sensor, complete new stanard exhaust, and both lamba probes replaced.
Any ideas what could be causing this ?
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Have you checked the fuel pipes for leaks? Also fuel and air filters. Has the ecu been interrogated?
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Sounds to me as it is running on both fuels at the same time. Turn the gas off at the tank and see if it is the same.
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The lucas 14CUX will raise the idle after starting if it see the battery voltage dip suring cranking, though that only explains the initial fast idle.
Check the stepper motor isn't stuck and also it might be worht checking the base idle speed. Fairly easy to do but a bit involved to explain (plus I'm at work) so PM me back if you can't find the how-to-do-it.
Check also the fuel pressure (metal tyre gauge onto the fuel rail, not a plastic one) and clean the injectors.
BTW, with all the bits it's had replaced I have to ask, did you do it or the previous owner? becasue it sound slike all the stuff I'd swap if I couldn't trace excessive fuel consumption!
You should check the TSR next to the ECU, it tell the ECY whether the car has lambdas or not, if not it runs open loop and uses the AMF, with them it runs closed loop and goes to the Lambdas rather than the MAF after 30 seconds of starting (base callibration). Default is WITH lambdas.
One big thing, a worn camshaft will manifest itself by chronicl fuel consumption BEFORE it becomes audible. Even a new chain will improve fuel consumption on an old cam, but the cam was around £60 last time I checked.
Call it £100 plus labour and if it makes a difference it will pay for itself, assuming you don't find a fault somewhere else.
5 mpg does sound bad though, I'd expect nearer 9 :wink: