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Matt
Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 20604
Experience:  BEng hons Mech engineering, in auto industry 22 years
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05 116 petrol 1.6 car was driving bad all of a sudden; client

Customer Question

05 116 petrol 1.6 car was driving bad all of a sudden; client rang and we picked it up and pluged in diag tool and no faults, have 3.6 bar pressure have spark but wetting plugs turning over fine and have compression attemting 2 fire
Submitted: 2 years ago.
Category: Car
Expert:  Matt replied 2 years ago.
Hello

if the engine is misfiring its possibly running too rich?
this could be incorrect fuelling due to a faulty water temp sensor. If this is the problem then the ECU will be leaving the car constantly ' on choke' and not reducing the fuelling as the engine warms - so unplug the sensor and clean the contacts on both sides with some switch / electrical cleaner (not WD40) and inspect the wiring for any signs of damage to the insulation especially where it runs over other components and through the bulkhead- if this doesn't help consider replacing the sensor as they're not expensive


Also check for exhaust leaks before the O2 sensor as if this has been experiencing an exhaust leak then it will have been running very rich as the sensor will see the extra air pulled in as fresh / lean fuelling and be adding fuel to compensate.

this can lead to catalyst failure as the extra fuel can re-light inside and melt the catalyst

The best way to find an exhaust leak is to run the engine from cold and feel around the exhaust joints with your bare hands - you'll have about 30 seconds before it all gets too hot and you should feel any escaping gas blowing over your fingers

Customer: replied 2 years ago.

car is a none runner its firing but wont kick off due to plugs being wet i think

Expert:  Matt replied 2 years ago.


Hello Liam

thats possible and would fit the symptoms of running too rich, I'd remove the plugs to get them to dry out and then try disconneticng the coolant temperature sensor as the 1st thing

as this will force the ECU into using a default / warm engine value
Customer: replied 2 years ago.
Relist: Answer quality.
car wont start
Customer: replied 2 years ago.
Relist: Answer quality.
car wont start
Expert:  Matt replied 2 years ago.
Hello Liam

have you tried disconnecting the coolant sensor as i've suggested?

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