my toyota 5 litre diesel smocks black on going up hills and reduces efficience. this normaly happence together with delayed gear changes being an automatic vehicle, the rave counter will go up to 4 instead of normally 3. however on straight roads it normally changes on 3 but when going on up hill i have to rave up to 4. when it changes to the next gear the smoke stop. i have recently changed the air filter after the warning sign had appeared but the sign could not go off. a mechanic has advise me that i have to disconect the battery for a while for the air filter warning sign go off. what could be the problem for the above.
A diesel engine spewing black smoke is generally caused by ignition timing that has been retarded too far or a large amount of unburned fuel leaving the engine. A failing turbocharger that is not putting out enough boost may cause the engine to run very rich under load and spew black smoke.
Consider hiring an experienced technician like one from YourMechanic who can come out and take a closer look at the black smoke problem and offer a more personal diagnosis.
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