Rover 420iS mystery - Priceyj
I have a Sept 1999 Rover 420 IS with 77,000 miles on the clock. It has been regularly serviced at the required intervals & has been a brilliant car. However, it has recently started to run very roughly from starting & continues like this throughout the day-does sometimes get better but is particularly noticeable if in too high a gear.
The mechanic who services the car has changed the leads & the plugs and I have filled up the last 3 times with BP Ultimate,with a shot of Redex in each time but none of this has cured the problem.
My mechanic is at a loss & I wonder if you have any suggestions,please?

So far for this problem we have:-
> Replaced leads & plugs
> Run a compression test-all OK
> Run a scan on the firing-all OK
> Replaced manifold inlet gasket-due to air leak
> Replaced injector seals (8)-1 damaged causing air leak
> Gas treatment
> Ran a test on swapping injector 1 with 2 (possible spray
> deficiency)-all OK
> Still no resolution! Guess what we need is a gnarled old Rover
> mechanic/engineer who would have come across the same problem-or a
> complete
> diagnostic test from a Rover place with all the gear, but where do
> you find
> one of those?

Rover 420iS mystery - tr7v8
Head gasket or cracked head! Seen it before.
Rover 420iS mystery - bbroomlea{P}
sorry to disagree but I would have gone for sticking valves. The 2litre T series can suffer from this, even if it has been looked after, besides which if the head was cracked or the head gasket gone it would have showed up on the compression test.

An engine flush may help, as would running it on diesel oil for 1000 miles and then change it, at least that is what my dad did with his 820 with the same engine and cured it for a good 15,000miles and had very similar problems to what you describe.

May be worth popping over to and post in their technical section and asking the question there as well.

Rover 420iS mystery - Priceyj
Many thanks for your suggestions. As an update, I took it along today to a chap at a Rover service garage I managed to find & he lifted each lead in turn with the engine running-numbers 3 & 4 went clack clack as they should but 2 & 1 were very much quieter. The car still drives to over 70 but is drinking fuel like anything.
Rover 420iS mystery - 420 Turbo Diesel
Could it be a collapsed Catalitic Converter?
I do like my Diesels to be Turbocharged for that extra OOMPH!!!!
Rover 420iS mystery - Priceyj
How can I tell if it's collapsed?
Rover 420iS mystery - Civic8
>>but is drinking fuel like anything.

is the Temp guage working ok?,ie does it reach temp ok,or does it take a long time to get there

Rover 420iS mystery - bell boy
according to autodata the map sensor is built into the ecm check that the hose to this isnt blocked (carefully as the maps are sensitive)
Rover 420iS mystery - Priceyj
Steve, went from bottom to mid gauge within 3 miles & stayed there

Rover 420iS mystery - Priceyj
Does it have to be diesel oil or maybe a much lighter ordinary oil? Will this unstick the valves, presumably in 1 & 2 cylinders? Also getting suggestions in mg-rover as you suggested!
Rover 420iS mystery - kithmo
Could it be the coil pack ? (or its connections).
Rover 420iS mystery - Priceyj
Seems it may well be sticking valves.
Do you mean drain the engine oil & refill with diesel fuel directly into the engine instead of ordinary engine oil?

Not getting much out of mg-rover site!
Rover 420iS mystery - Brit_in_Germany
While having no suggestion for curing this, I am not sure bbroollea was suggesting filling the sump with diesel! Perhaps by diesel oil, an oil suitable for diesel engines was meant?

Rover 420iS mystery - Priceyj
Am desperately trying to find out exactly what he did mean but can't get a response!!
Rover 420iS mystery - Civic8
Diesel engine oil is what is meant-not fuel oil-It does on some engines work ok but not a stripdown is required depends how sticky the valve/s are
Rover 420iS mystery - Priceyj
bbroomlea- please see my reply & question below

Rover 420iS mystery - Robin the Technician
An obvious oversight here - the distibutor cap. If its never been changed then the running conditions you describe are pretty typical after the mileage its covered. Get the cap changed (and the rotor arm at the same time) and i think you'll notice an improvement.

These are the views of Robin the Technician with 35 years in the trade. I fix, therefore I am...
Rover 420iS mystery - Priceyj
As you will know-this car does not have a distributor but has a coil pack!
Rover 420iS mystery - Civic8
>>As you will know-this car does not have a distributor but has a coil pack!

Which often cause problems,Have you had a diagnostics carried out yet in case you have an electrical problem, as it may be electrical rather than mechanical
Rover 420iS mystery - Priceyj
No,not yet as I will have to leave the car with them for a few days & I need the car to get to work!! Catch 22!!

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