Rough running until warm

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Johny h

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20
Location
Sunderland
2005, 2.7 tdv6 no fault codes at all! Engine runs really rough and very nearly cuts out sometimes until the engine is warm - after 5-10minutes. The car then runs perfect. Any ideas - please!
 
Garage has drained some fuel from the ‘return’ and it has a few metal particles! They suggest removing injectors and testing them, draining and cleaning the entire fuel system and maybe pump. This would cost a fortune and I don’t think is worth the chance. They can’t be sure this will solve the rough idle anyway!

when returning from the garage today I hit traffic while the car was cold and the misfire/rough idle was terrible! Once warmed up the car ran perfect again.

I am still hoping for an easier solution before I spend huge sums of money on a gamble.
 
Metal shavings mostly come from the pump as there are more moving parts.
Any garage would consider having the injectors and pump tested and proceed from there. You may be correct, it could get expensive pretty fast....
 
Not much clue on doozles but I'd expect coolant, air and fuel sensors at least. If one is'stuck' at a hot reading, not sure if would show as a fault but a diag tool will pick it up
 
Garage has drained some fuel from the ‘return’ and it has a few metal particles!
Have you see these particles? Any particulate matter more than a few microns across will block the injector spray nozzles, which would be permanent, not clear when hot.
They suggest removing injectors and testing them
That's only helpful if the injectors are OK. If they prove to be faulty, you'll pay to test duff injectors, then buy new ones to fit in their place. I'd be doing an injector offset diagnostic before pulling the injectors unnecessarily.
This would cost a fortune and I don’t think is worth the chance. They can’t be sure this will solve the rough idle anyway!
With the correct diagnosis, there's no need for guessing as to the cause.

Was the oil temperature sensor replaced, as suggested in the last thread on the same subject?
 
Have you see these particles? Any particulate matter more than a few microns across will block the injector spray nozzles, which would be permanent, not clear when hot.

I have seen a sample of the fuel, it had a few very small specs of what might be metal along with some small specs of black carbon.

the injectors must not be blocked when hot as it runs perfectly once up to temp. Which is why I don’t agree with the garage diagnostic.

That's only helpful if the injectors are OK. If they prove to be faulty, you'll pay to test duff injectors, then buy new ones to fit in their place. I'd be doing an injector offset diagnostic before pulling the injectors unnecessarily.

With the correct diagnosis, there's no need for guessing as to the cause.

Was the oil temperature sensor replaced, as suggested in the last thread on the same subject?
 
The oil temp sensor has not been changed yet as the garage can’t see a fault on it.
Many time a sensor doesn't flag a fault, but it can still be faulty. A faulty sensor can return an out of spec signal, but because its returning a signal, the ECM won't flag it. This is really common, and unfortunately requires experience on a particular engine, to know such issues exist.

What about the metal in the fuel? I don't see how metal in the fuel only affects it when cold, as if there was particulates in the fuel, it would effect the running all the time.
It sounds like they're clueless, and don't understand how to diagnose faults, or after work.

If I couldn't fix it myself, I'd take it to someone else for another opinion.
 
I’m no mechanic but I agree with what you say about the blocked injector. If it’s blocked with metal fragments it’s not going to clear when up to temperature.

The problem is only present when cold and soon disappears, knowing a trust worthy knowledgable garage is the problem.

Is it worth running injector cleaner through it?
 
do you have diagnostics? see what reading you get from all the sensors when cold, they should all be around the same whatever the ambient temp is
 
Metal in fuel = run away fast.
Iirc the injectors have a small filter in each so that means the metal can only have come from HPFP and if so the whole fuel system right back to the fuel tank could be contaminated.
Van guys where I used to work dealt with misfuels all the time, misfuel = swarf in the fuel system, hpfp and injectors off for testing, tank off for cleaning and all fuel ines flushed/blown through, ie a lot of time and money.

I would say fit a new oil temp sensor regardless of what garage says, at 30 quid you have to try, then if the same its get rid time.

You really should carry on with threads rather than start new ones as it causes confusion, and people in the future will not be able to follow what has happened in your quest to fix the thing.
 
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