Mercury cougar 2002 with a P0171 & now P0301 codes

Question

If the timing was off would it cause this because all this started (4 Months ago) when the timing belt was replaced?

Answer 1

P0171 Fuel trim Bank 1

P0301 Misfire cylinder number 1

Yes a timing belt off a tooth can cause the misfire condition . A timing belt that is off its timing mark would also cause the engine to buckle as it accelerates. A simple inspection of the timing mark alignment is all that is required to determine if the timing belt installation is the cause, If the timing belt is aligned properly and is not the cause, what needs to be checked is a vacuum , a disconnected vacuum hose or even the intake manifold gasket taking in false air has to be checked. The vacuum leak would be found at or around the number 1 cylinder. And this includes the EGR.

Comments

I have been trying to find a leak or what the heck is wrong for months now I can't find any replaced all kinds of things nothing helps

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The intake manifold on these engine tends to leak you can use brake cleaner or carburetor cleaner a spray along the intake and note any change