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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 20357
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Diesel transit loses power then picks back up

Customer Question

diesel transit loses power then picks back up
Submitted: 9 months ago.
Category: Car
Customer: replied 9 months ago.
(Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Matt replied 9 months ago.
Hello 1st check the connections to the EGR valve, if either the vacuum pipe of electrical connection are damaged / corroded then the EGR can be on all time 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 then check the small vacuum lines to the turbo and its connected control solenoid on the bulkhead, any cracks or leaks can give turbo issues and its best to have the boost pressure measured actually measured with a boost gauge to check that the turbo is healthy and that the sensor is reading correctly If its a variable vane 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 worth checking that the glow-plug relay is switching off as they can stick on and leave the glow plugs also on - on some cars this can force it into limp home Also worth considering adding a bottle of injector cleaner into the tank as a clogged injector nozzle will reduce power and give 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 the high 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 end caps off under high boost. If the above are all 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 on the fault light and you can sometime 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.
Expert:  Matt replied 9 months ago.
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