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Matt
Matt, Mechanical Engineer
Category: Vauxhall
Satisfied Customers: 20600
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Have a 1.8 insignia Sri. The engine starts to splutter /

Customer Question

Have a 1.8 insignia Sri . The engine starts to splutter / shudder under exceleration . Starts up fine but if you Rev it , does the same thing . No management light comes up so is it the plugs or could it be the coil pack .
Submitted: 4 months ago.
Category: Vauxhall
Expert:  Matt replied 4 months ago.

Hello

This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by theECU and so not compensated for and can lean the engine out and can also allowthe 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 hoseclips 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 yourleak.

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 sparkto 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 oflighter 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 ofcorrosion or damage. you can do a quick fault find if you unplug the meter andrun 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 noaccount touch the wires with anything as they are very fragile

Expert:  Matt replied 3 months ago.

Hi

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