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Matt
Matt, Mechanical Engineer
Category: UK Car
Satisfied Customers: 20584
Experience:  BEng hons Mech engineering, in auto industry 22 years
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My 2003 vauxhall vectra is not ticking over very good I have

Customer Question

hi my 2003 vauxhall vectra is not ticking over very good I have changed fuel filter and changed gasket on carburetor body but still no change I was gonna change idle control valve but not sure where it is or to go ahead with it or not
JA: Is the fuel filter an external one, or is it inside the tank?
Customer: It's an external one at the bottom of the tank
JA: What is the model of your '03 Vauxhall?
Customer: 1•8 LS KA03BVL
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: got a neil our who is a mechanic I have changed fuel filter and gasket on carburetor body but still no change
JA: Anything else you want the mechanic to know before I connect you?
Customer: No
Submitted: 2 months ago.
Category: UK Car
Expert:  Matt replied 2 months ago.

Hello

This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.

if the engine condition is the same then chances are the meter or the connection to it is faulty

It’s also worth cleaning the MAF sensor wires, as they can get coated with dirt over time which then offsets the reading

Use some contact cleaner or brake cleaner to spray onto the wires to remove the dirt – on no account touch the wires with anything as they are very fragile

Customer: replied 2 months ago.
hi I have changed the fuel filter last night I also changed gasket on carburetor body but still no difference but I was considering changing the idle control valve to see if that would help
Customer: replied 2 months ago.
It seems to be that when it is stationery the problems start but ok when driving
Customer: replied 2 months ago.
There are no warning lights on the dashboard
Expert:  Matt replied 2 months ago.

Hello

Ok

try checking for airleaks in the manner I've described and let me know what you find

Expert:  Matt replied 2 months ago.

Hi

do you still need help?

Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you

Customer: replied 2 months ago.
hi it sometimes backfires as well
Expert:  Matt replied 2 months ago.

hello

OK a bad vacuum leak can create a lean misfire / backfire

but its also worth checking

Check the resistance of the spark plug leads ( 13-15Kohm / metre) and replace if any doubt or high resistance - Also replace the spark plugs if any of them fail this checklist:

http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp

You can also try spraying some water on the coil pack with the engine running. It is possible the coil is faulty and causing the misfire. If you see sparks arcing with the water, then replace the coil.

Customer: replied 2 months ago.
hi when it went fir MOT in nay it came back with recommendation for flexie hose leading into main exhaust needs replaced slightly caroded could this be the problem with it ticking over as well ?
Expert:  Matt replied 2 months ago.

hello

if the exhaust is leaking before the oxygen sensors then yes it can effect the idle as the closed loop fuel control will be in error

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

Expert:  Matt replied 1 month ago.

Hi

do you still need help?

Bear in mind that the site takes a deposit from you at the beginning andthis is held by the site until you rate my answer at which point the cash issplit between the site and the expert. I am only paid for my work on thisquestion if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you

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