'93 V8i revving @ idle

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nzoliver

nzoliver

Member
Posts
67
Location
Christchurch, New Zealand
Hi all and Happy New Year from the sunny south Pacific!!:welcome:

I have a couple of problems with me '93 Camel Trophy Disco V8i (yes it IS a Special Vehicles - A promo vehicle);)

#1: When I start it from cold it goes up to about 1800rpm :eek:and sits there. :eek: I shut it off at the mo and re-start it and that normally stops it.

#2: When coming to an intersection or similar, it seems to be revving against the brakes. Chuck it into N(Auto) and it revs to about 1500 and drops back slowly in steps over about 6-8 seconds. :5bwilly_nilly: It's driving me mad and i'll bet using a bit of fuel too.

DO these trucks have a sensor or something to tell the ECU that it is moving? If the revs are up at 1200- 1500 and i am coasting in N it won't come down to idle until I stop the truck. :confused::5btoetap05:

#3: It stinks of petrol when the tank is quite full only and usually only after driving it. I can smell it in the cab too. I live up a steep hill and fill up on the way home so it works HARD as the hill is STEEP. :5bdriving: It's like there is something to do with breathing in the return line to the fuel tank.:rolleyes:

Any input would be fab.:boink:

Thanks

Oliver:pop2:
 
They do have a speed transducer for gearbox, this could cause the over reving at junctions.
It could be a lot of things.

I ain't clued up about v8's anymore but some1 will be along shortly.

Or pm mr noisey
 
Hi Oliver,

Cricky....over-revving V8s....There's loads to look at.
I'm assuming it was ok before, but now it's not?
The simpliest things to do first... Check the engine air filter (any over resistance there will cause over revving), breather and pipes inc around the t connector that easily and frequently blocks with hard run engines.
Basically look at your air-intake and breather system first. take em off and clean throughly, including the first sensor to check which is the MAF on the intake pipe.


Good luck
 
nzoliver said:
Hi all and Happy New Year from the sunny south Pacific!!:welcome:

I have a couple of problems with me '93 Camel Trophy Disco V8i (yes it IS a Special Vehicles - A promo vehicle);)

#1: When I start it from cold it goes up to about 1800rpm :eek:and sits there. :eek: I shut it off at the mo and re-start it and that normally stops it.

#2: When coming to an intersection or similar, it seems to be revving against the brakes. Chuck it into N(Auto) and it revs to about 1500 and drops back slowly in steps over about 6-8 seconds. :5bwilly_nilly: It's driving me mad and i'll bet using a bit of fuel too.

DO these trucks have a sensor or something to tell the ECU that it is moving? If the revs are up at 1200- 1500 and i am coasting in N it won't come down to idle until I stop the truck. :confused::5btoetap05:

#3: It stinks of petrol when the tank is quite full only and usually only after driving it. I can smell it in the cab too. I live up a steep hill and fill up on the way home so it works HARD as the hill is STEEP. :5bdriving: It's like there is something to do with breathing in the return line to the fuel tank.:rolleyes:

Any input would be fab.:boink:

Thanks

Oliver:pop2:
Click to expand...

Idle problems are quite common (do a search). Do the easy stuff first, check and clean the stepper motor (idle stabilisation valve). Check the plenum and all vac hoses for air leaks/splits/tears etc.

There is a speed sensor. The 14 CUX ECU looks for a signal from it to tell it to turn off (or on) idle stabilisation. Normally if the speed sensor goes down you'll lose your speedo.

The smell of petrol is most likely to be corroded fuel pipes. Have a careful look at the back of the chassis where the pipes sit on top (follow lines back from fuel filter to tank). You can also see a bit better if you lift the boot carpet and take out the access panel for the fuel tank.
 
Is it a 3.5 or 3.9?

Because they have different types of speed sense.

On my 3.5 when the speed sensor failed I had cutting out at traffic lights because the idle control was not switching back on. It did not idle high though.

I'm saying for now as above air leak or stepper failure/sticking etc.

Regards the fuel smell, it could actually be rotten fuel lines? Not sure what spec the vehicle is or it's corrosion status but my lines had rotted through so there was a long for a while before the leak, or does your car have a fancy evaporative emissions system?

It has the crude tank breather which my 92 had fitted just failed/cracked??

Cheers :)
 
Turns out I have a similar issue, when moving (even 1mph) it sits at 1200ish until I stop. rather annoying if you want to go slow. going to look at testing the speed transducer
 
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