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Matt
Matt, Engineer
Category: Nissan
Satisfied Customers: 20812
Experience:  BEng hons Mech engineering, worked in auto industry for 22 years on engine, transmission and suspension design
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Quest: 2005 Quest On a trip across the country. We've stopped

Customer Question

2005 Quest
On a trip across the country. We've stopped for a week in AZ. Just today the van started to sputter, as if it's misfiring. The engine light was on but now is starting to flash. Just before I turned the engine off, the light was steady again. I opened the hood and when the gas pedal was depressed (rev the engine) I heard a quick sucking sound from under the air filter. It feels as if the van is misfiring or not running on all cylinders.
Submitted: 1 year ago.
Category: Nissan
Expert:  Matt replied 1 year 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 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 tolocate 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 beworth 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 isfaulty Air leaks are very temperature dependent as gaps can open or close up as things expand with heat,so the weather and engine temperature can effect them. This leads them tobe quite intermittent in the case of mild leaks its also worthcleaning the airflow meter by removing it from the car and spraying the exposedsensor wires inside the tube with a brake or switch cleaner - ensure that thecleaner is one of the old fashioned, non Eco type that does not leave a residue On no accounttouch the sensor wires with anything physical as they are extremely fragile
Expert:  Matt replied 1 year ago.
Hi
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