Engine Management light on

[David Loft]

Before having a full service recently the car had a bit of an erratic idol at tick over. Had the service done, all filters, fuel filter, oils, spark plugs etc etc replaced. 
 

erratic idol still existed, after a couple of fuel injector cleaner solutions added to the fuel at full tanks, the engine management light came on. I have plugged the car in to a reader, only two codes came up one for a clutch sensor which was green but a lean fuel code came up, nothing else, no mass air flow sensor codes, or anything else, my mechanic wasn’t too worried and reset the E/M light. Half way home of a 200mile journey it come  back on again. 
 

now the start up is really laboured, 3 to 4 long turn overs be fore it fires up, and stop start journeys the car starts up straight away, but after an hour of non use the car goes back to the start up issues.  There is no smoke discharge at all, although now does smell a bit rich at first turn over. MPG Is way down as well from 32mpg to 22mpg. 
 

no miss fire codes or any other fault code available . 
 

can any one shed some light 

 

its the 1.8 turbo petrol engine 

[Steve Q]

It might need a diagnostic check with a more sophisticated diagnostic system, no disrespect to your code reader. 

Erratic idle as you've rightly suggested could be the maf sensor but also the lambda sensor, cam position sensor, crank sensor, injector or injector seal etc. 

[David Loft]

Upon reflection is it possible the fuel pump is giving up, as per the hard turnovers before starting, not so perfect idling, lean reading and not so good mpg ?
 

My mechanic has a sophisticated code reader and every check he did came back with no fault apart from the lean reading 

Edited 3 hours ago by David Loft

[Magnet]

Petrol or diesel David? 

[daveyboy1967]

He says it's the 1.8 turbo petrol in the OP.

[Magnet]

OK David -missed that last sentence. 
 

Possible coolant temperature sensor that senses the coolant temperature and signals the ECU to provide the correct mixture in relation to coolant temperature?? 
 

They can fail to an arbitrary condition where starting and running mixture is too weak.