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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22739
Experience:  BEng hons Mech engineering, in auto industry 22 years
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I have a mk6 transit van 2.0 and recently changed the egr

Customer Question

Hi I have a mk6 transit van 2.0 and recently changed the egr valve it was going brilliant for about a week but now it have started to over rev can you tell me the problem....thanks
Submitted: 2 years ago.
Category: Car
Expert:  Matt replied 2 years ago.
as its over-revving its likley to be overfuelling so I'd suggest trying a bottle of injector cleaner as a 1st step
if thats OK then I'd check the condition of the MAF wiring and connection for damage
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 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.
Customer: replied 2 years ago.
I'm 100% sure it's not the injectors, have the inside of the egr valve got to be lubed as it is a brand new part and looked way to clean to me and that was the last new part I changed then I had the revving problem....which only happens when the engine reaches its running temperature, would this make the egr valve stick and course the engine to idle...
Expert:  Matt replied 2 years ago.
hello the EGR valve doesn't need lubricating but if its brand new then it can have sharp edges which can catch so it would be worth removing it and checking that it moves freelyas its quite possible the new part is faulty