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Matt
Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 21622
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Deisel 2.2 mondeo engine hunting at high speed

Resolved Question:

deisel 2.2 mondeo engine hunting at high speed
Submitted: 2 years ago.
Category: Car
Expert:  Matt replied 2 years ago.
HelloIdeally measure the pressure at the inlet to the main engine fuel pump and if this is low check the pump as described and also consider changing the fuel filter as if this partially blocked this too will reduce pressure. If both of these are OK then also check the connections to the EGR valve, if either the vacuumpipe of electrical connection are damaged / corroded then the EGR can be on alltime which certainly will hurt performance. Its also possible that its a fault with the EGR valve so its worth removing the valve and cleaning it out with brake cleaner, if it looks particularly clogged then replace it. If this is OK thencheck the small vacuum lines to the turbo and its connected control solenoid onthe bulkhead, any cracks or leaks can give turbo issues and its best to havethe boost pressure measured actually measured with a boost gauge to check thatthe turbo is healthy and that the sensor is reading correctly If its a variablevane turbo (they’ll be an actuator on the turbo body - but not a wastegate)then check its vacuum pipework as above and check the connections to the diaphragm / solenoid valve Also worthconsidering adding a bottle of injector cleaner into the tank as a clogged injector nozzle will reduce power andgive poor combustion - the next stage on from this is to remove all the injectors and have them ultrasonically cleaned and flow checked Also check all thehigh pressure hoses post turbo/s for any split hoses or cracked metal pipes,also check the ends of the intercooler as its not unheard of to pop the endcaps off under high boost. If the above areall OK then try checking for airleaks after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and leans the engine out causing rough running. As its a mechanical fault it tends not to turn onthe fault light and you can sometime hear a 'hissing' noise with the engine running. Check the hoseclips for tightness and inspect the trunking for any cracks or splits and alsoall 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 gasaround each joint in turn. If the engine rev's up you've found your leak.Work your waythrough each possible joint one at a time and you should find it. I use aslightly 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 intoeach area, especially those difficult to reach with large implements. Might also beworth checking the wiring and connector to the airflow meter for any signs of corrosionor damage. you can do a quick fault find if you unplug the meter and run theengine without it.if the enginecondition is the same then chances are the meter or the connection to it isfaulty its also worth cleaning 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 the cleaner is one of the old fashioned, non Eco type that does not leave a residue On no account touch the sensor wires with anything physical as they are extremely fragile
Expert:  Matt replied 2 years ago.
Hi

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