by compression test
You have to disassemble the entire engine, remove the piston and check the rubber ring around that piston.
In some specs of cars, the type of petrol listed may be unleaded fuel, if you use leaded fuel, this will be detected by the engine activating the check engine sign. Tio eradicate this problem, you may need to drain your whole petrol tank and replace with unleade fuel only.
Sounds like you may have a serious internal engine problem i.e. bad valve or blown piston. Do a compression check to try to determine which cylinder(s) are involved and whether problem is with a valve, piston, or head gasket.
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The engine will be losing compression, and possibly burning oil. Check each cylinder to determine the compression. The loss could also be caused by a valve problem.
Check engine light on? Have vehicle scanned to determine the problem Bad spark plug or wire? Bad valve? Bad piston? Vacuum leak? Do a compression test
If it is not on, you do not have a problem.
engine check light is not on. right? if the fuel consumption is above the manufacture specification then please check the vehicles wheel alignment, dragging brakes and wheels air pressure etc.
under the bonnet on the engine
The only way to "check" a piston would be to remove it and visually inspect for damage and wear.Make certain that the piston is not cracked or otherwise damaged.check the ring grooves. Use a piston ring and a set of feeler gauges to determine the amount of wear. Excessive ring groove wear can result in piston failure and if the piston shatters, it can cause the engine to fail completely.Next, use a micrometer to determine the difference in the diameter of the piston between the top and bottom. The piston will wear and if the difference between the top and bottom is too great, the engine will exhibit "piston slap".Check the fit of the wrist pin, it should be tight.HOWEVERYou can run a compression test and get a good idea whether the piston is functioning somewhat correctly.
The check engine light comes on in a car when there is a problem with the engine. It will go off or be reset when the problem is fixed.
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