A bit of advise please

Thanks for the replies everyone, I know what you mean Philip everything points to the engine being fine theres no tapping noises on startup, no misses and the economy is good, the only thing that worries me is the black smoke and loss of power.

I might do a compression test first, that seems the cheapest place to start, no I haven't checked the PCV system. I've got no history on the car so I can only assume its not been done since its come out of the factory...

Idling is fine, but sometimes when I come off the freeway and sit at the traffic lights the engine idles at 1,500rpm, and then drops to 800 after a few seconds.

How do I check the temp sender to the ECU ? I'm guessing its the same sender that the temp gauge on the dash uses ? If so then its reading normal temp.

if it was running at all rich,, you wouldnt be getting 14's. plug chop sounds the go---

G`day Duncan

Check your fuel pressure regulator .

There is a vacuum pipe going to it , remove this and any sign or form of fuel on the hose side says it needs replacing .

It lowers the pressure for slower running and increases for faster running .

With your economy it has to be something that alters with revs .

Cheers

Yeah, check the easy things first. I was thinking maybe a vacuum leak? It's easy for any vacuum hose to spring a leak, so be sure to check them and of course all connections, fittings, etc.

Does this jigger have an EGO sensor, and, if so, is it faulty?

1 The temp sender for the ECU is not the same as for the gauge. The gauge one is a single wire sitting next to the thermostat housing, the ECU is on top of the manifold at the front RH, and has 2 wires and an injector plug on it. It should read about 300Ohms at normal operating temp.

2 No EGO sensor

3 look I say again , I think it is fine. The soot you see may be water condensing on a cold exhaust.
Regards Philip A

As you are in Perth, drop in to either Jordan Rovertech or Guest and Puddey and get the ECU checked. If you have an injection fault, it will send the ECU into 'limp mode" which will make it run rich. generally the fault can be cleared, but it will depend on what the actual fault is.
Its also worth while checking the pressure regulator on the fuel rail to see if it has stuck open. The fuel rails have a habit of rusting inside and small bits of junk can clog the regulator in an open, or possibly in this case, a closed position increasing the injector pressure. Normal injection pressure should be about 36 psi. Any higher and you are pushing a lot more fuel thru the nozzles.
Thermostat stuck open or the lack of one in the first place is also something to look at!:eek:

At 1 litre/5000 km, I'd say that's better than average for a RR V8! I wouldn't complain about that.

What plugs are you running? Are they too cold?

Quote:

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Originally Posted by PhilipA

If you are getting 14l per 100Kms on the freeway and using 1 litre of oil per 5000K, to me it seems there is nothing wrong with your engine.

You don't start her up cold and move her into the driveway before you check the plugs do you?
If you have no misses or poor starting and the fuel economy is good, stop worrying.
The plugs are always sooted on one side on any V8. A bit of idling or a cold start will probably spread it. Why not try driving at 100Kmh on the freeway, then turn off immediately and check the plugs.
Regards Philip A

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I'm curious about the comment that 'plugs are always sooted on one side of any V8' - if they've got equal fuel feed and similar independent extractors, why would this be? One of the reasons I ask is because I've got a tranverse mounted parallel twin motorbike (TRX850) and it always runs richer on one side (and soots the plug) and I've been told that one cylinder runs hotter than the other on this bike - which I can't work out because they've got equal airflow and similar but independent carbs and exhaust. Surely there wouldn't be big differences in the water channels on each side of the block? Anyway, fortunately on a motorbike with carbs this is easily accounted for by adjusting the jets/needles on each carby independently until neither runs rich.

I have done tuneups on V8 ski boats in the past where I fitted different heat range plugs to each bank to cure fouling issues. Raw water cooling with no thermostat means each bank runs at considerably different temeratures.