Modern Mondeo has started flooding badly

[Colin Lindsay]

My trailer-hauling workhorse of a 2007 1.6 petrol Mondeo has started flooding badly; it misses a bit when driving and last night there was a tremendous smell of petrol once I parked up, presumably from the exhaust. It starts fine from cold but if you do a short journey it's hard to start again.

This morning after a 20 minute run, I parked it in a car park, restarted it and got a huge cloud of bluey-black smoke out of the exhaust, which then cleared again.

I've run a diagnostic on it which tells me there is a weak injector gate (no 4) but that shouldn't cause rich running? Any chance that it's a MAF sensor?

Any other ideas?

 

 

 

[Pete Lewis]

Would a weak gate allow excess fueling ,  how is the cold starting richness  controlled ?  Is the erg valve clean and working, ?

Not stuck and something is over compensating ?

After that

Pass

 

Pete

[Colin Lindsay]

I had thought a weak gate would be a weaker mixture, rather than rich. It's got to be an intake sensor giving a false reading and so leading to excess fuel, but which, if nothing shows on the OBD reader? I hate moderns.

[NonMember]

I think a weak "gate" might mean the injector is leaking fuel all the time, which would result in very rich running.

[Colin Lindsay]

That's a possibility. I've the various bits off just this minute - freezing cold notwithstanding - and will see what the cylinder / injector is like.

[Conor L]

I'm assuming this problem has been fixed but rich running could be due to a faulty coolant temperature switch. If that is reading cold figures the ECU will think that the temperature is colder than it actually is so the engine will run a richer mixture when it doesnt need to. Had this on a BMW Mini a couple of weeks ago.

[poppyman]

Hi Colin, Maf sensor failure will normally cause non start from cold. Egr valve could be a problem if stuck with crap (you can try disconnecting it)  And as Conor say's poss temp sensor, although guage would usually show an odd reading. Also have you checked your oil level? Last but not least check the wires on the Lamda sensor or remove and clean the sensor with a wire brush.

Tony.

[Colin Lindsay]

2 hours ago, Conor L said:

I'm assuming this problem has been fixed but rich running could be due to a faulty coolant temperature switch. If that is reading cold figures the ECU will think that the temperature is colder than it actually is so the engine will run a richer mixture when it doesnt need to. Had this on a BMW Mini a couple of weeks ago.

Possibly! I cleaned everything thoroughly, damp-proofed it all and reassembled, then cleared the code using an OBD reader, it never came back, nor did the smell of fuel. Petrol consumption is 36.9 MPG which seems to be same as usual. I think I'm slightly down on power - very slightly - but then as I'm always hauling trailers or carrying bootfuls of hardware it's hard to tell... 

[Anglefire]

The other one to check I oil temperature sensor - been known to cause issues of a similar nature on land rovers - if you can read the live values via a diagnostic tool it could save some money. 

[Colin Lindsay]

Got it sorted - bad fuel injector (no4) - replaced it and no problems since.