Drove to the pub the other day, perfect. When I came to drive off, she wouldn’t start. After a few times with foot down on throttle she started but with a misfire and terrible black smoke, seems a lot of smell of fuel. Undrivable in that condition.
I managed to get the AS to recover to local garage. He did swap all relays and code read it but it was difficult to keep revs up. The only fault was p1251 but that was because the relays had been swapped all over the place.
In the recent past she’s has new AITS , TPS, MAF, CTS, so I know it’s not them.
the EML is on and “failsafe engine mode “.

the only other thing it was suggested by the mechanic was coil pack failure .
Is it right that if a coil pack goes, it just goes dead? Does each cylinder/plug have its own coil pack on these V8s?

Suggestions most appreciated!
cheers!

 

Why the garage was replacing the relays and what relays were replaced? These cars has tons of relays. Engines in these cars has COP ignition that means coil on plug. So 8 coils and 8 plugs. Black smoke tells that there is loads of unburnt fuel. Rest of it burns in the exhaust pipes. First thing is to narrow misfiring cylinders down. Either running engine long enough to ecm diagnose it by itself or mechanic to find it. Is it only one or two or so. Or is it completely random cylinder that is misfiring. Then is it misfiring of lack of fuel or because way too much fuel. Are temperature sensors reading correct ?

 

Yeah nothing wrong with any sensors. She all of a sudden did this. So my question is, if a coil pack one one, maybe two, plugs went, would it then all of a sudden create this issue.
cheers

 

My first question is: Do you have a locking gas cap?

 

Yeah it’s a locking cap….

 

That's good...one of my first thoughts when a car is running great and
then all of a sudden, it is not....is a polluted gas tank. That coming from
a possible envious person introducing something foreign Into your gas
or filling the car up from a station whose gasoline is less than desirable.
In your case however, it would seem to be more likely an electrical issue
that suddenly escalated during a driving cycle..

 

Why did the garage swap relays at all? This seems like an odd way to diagnose this problem. When you say the garage swapped all relays, you mean literally all relays in the car, so the relay for the taillamps was swapped out as was the one for the secondary fuel pump and all that? Or just the ones in one particular fusebox?

I'm also left wondering why swapping any relays around would cause a code P1251, which is a throttle motor relay malfunction...were they swapping relays around while the car was running or something?

 

Yes whilst ignition on. It is very strange, as she now runs ok with the old MAF which originally threw up the engine failsafe mode and the MAF code in the first place.
My only conclusion is I sprayed too much electrical cleaner in the plug connection for the original maf.