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Robert, UK Qualified Car Technician
Category: Car
Satisfied Customers: 4708
Experience:  Fully qualified / self employed garage technician in the UK
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My Jeep has a replacement head and injectors but now emits

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My Jeep has a replacement head and injectors but now emits black smoke out of the exhaust when overtaking. Why?


Ok..If there is Black smoke then its usually a sign of an air to fuel ratio imbalance, either your fuel system is delivering too much fuel.diesel into the engine or there is not enough incomplete combustion- caused by blocked air filter/ faulty injector(s) ie;- leaky fuel injector/fault pushing too much fuel through but considering you have had these changed calibrated i cant see it being the next usually the first places to check would be the intake system pipe work circuit ie: starting off from the air filter checking its clean and follow all the way checking for any possible restrictions /tears or small holes in the pipe work leaks etc.there is the possibility of faulty mass air flow meter/check the conections and wiring there too for issues so maybe check inside the meter itself and ensure its not fouled up you can get mass air flow spray cleaners but brake cleaner sprayed in via the opposite direction of air flow should help..just check the screen is clear ..Another area to check up on the EGR valve "exhaust gas recirculation valve unit" to ensure its not at fault these do become faulty can in a sense cause black smoke if the samll valve that allows exhaust gas back into the intake cycle sticks check that too

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