The V8 Owners Forum -

hi there,

ive reached the point where im not sure what to do. i have a rover 3.9l efi in a cobra replica. Been having problems with it for a while now and cant work out what is wrong. It has recently returned from a garage after having a load of tests done but nothing untoward found. these are the tests that were done:

Fuel supply/return pipes - nff
Fuel pressure/pressure regulator operation - nff (36psi min)
fuel condition i.e.: water ingress - nff
fuel rail/injector leak test (initially thought to have failed upon removing and retesting turned out to be a fault with the pressure gauge) - nff
fuel injector pattern/flow test.- ok (they haven't been duty cycled)
Ignition timing - static/idle & maximum mechanical advance. - nff (10*idle, 30* full advance)
ECU/engine earth points cleaned secured..- ok
ECU coolant thermistor operation/multi plug condition.- nff
Injector electrical pulse (noid) test.- nff
Throttle potentiometer operation - nff
Engine compression test - ok (c150psi)
ignition system - rotor/cap/leads/plugs.- nff
Air flow meter operation/adjustment. T.B.C
Visual inspection of engine wiring loom (where accessible). - nff
Check for inlet air leaks (where accessible) - nff

Now, the main reason for sending the car to the garage was becuase the engine sounded like it was mis-firing and was running rich as there was popping and banging at all revs and a lot of black oil particles coming out of one of the exhaust pipes - the injectors had been sent off separately about a year ago and these were all tested, refurbished and refitted - do they jam easily if left unused?

Does anyone have any idea where to go from here, the gargage was listing the following as next course of action but i was reluctant as i hoped a specific avenue would have been found to go down rather than testing everything:

removal and testing of all injectors to include duty cycle
removal/inspection/replace inlet manifold gasket
inspect cam shaft & valve gear.
Remove dashboard to access ECU, remove multiplug and 'pin out' engine harness
Test ECU

the car has been sitting for years due to the above but before that was running beautifully for a long time. Any help greatly received

I's be very surprised if your garage could test a Lucas ECU.

When you tested the CTS, what results did you get?

Does the popping/black smoke change as the engine warms up?

Just to be sure - is this a hotwire or flapper system?

sorry, im not sure what CTS is?

there's not so much black smoke but when i put my hand over the exhaust about an inch away, lots of small specks of oil and the exhaust is very harsh smelling generally

and its a flapper system - cold start injector on side of the plenum is usually unplugged

CTS is the coolant temperature sensor. If this fails open circuit (the most likely way) the ECU will think the engine cold and go maximum rich.

Easily checked at home with a DVM.

The cold start injector isn't controlled by the ECU. No need to unplug it as it only operates below a certain temperature. The engine will start on all but the coldest day without it, though.

Sounds like the system wants a thorough check through. Sadly, very few garages understand it well.

Check your spark plugs.
Are all electrodes similar colour? If not the different one is showing the problem cylinder
Are they all the same brand and heat range? If so what?

Wait till dark
Open bonnet
Start car, look at wiring for spark show, to see if spark is escaping before plug.

Would be my first test

Ian

New leads and dizzy cap.

DEVONMAN wrote:

New leads and dizzy cap.

Original ...............not after market

Ian

At least on the hotwire setup, if you remove the water heater under the throttle you need to ensure the two holes in the left side of this picture are plugged up - as they go direct into the manifold and cause an air leak which causes rough running.

thanks for the replies guys, much appreciated. i shall investigate further and see what happens

http://www.cowdery.org.uk/downloads/FlapperManual.zip is the Land Rover manual.
http://www.cowdery.org.uk/downloads/V8EFiSystem.pdf is a TVR interpretation of the same.

Chris.

Did you have any luck sorting the problem?

Ian

So the problem is you perceive it is running rich....but you also state oil and black particles coming from one exhaust pipe only ?

Is that one exhaust per bank, or other ?

And is it actually running rich ? What sort of mixtures is it seeing ? Hydrocarbons ? Again, for each bank if possible.

And does this correspond with injector pulse widths for each bank ? ie are they excessively high ?

Injectors can give issues if laid up for a long time, but it really depends what the last fluid was through them and how they were stored.

But you dont seem to be suggesting it is off cylinders as per a stuck injector.