Can driving with misfire cause engine damage?

Title. Can driving with single cylinder misfire due to lean condition cause major engine damage and if so what? (Piston rings, valve stems, etc.) I have a misfire on cylinder 3 on my 4 cyl car for the first 1-2 minutes of driving then it goes away. What damage do I risk to my engine if any if I continue to drive it like this? Mechanic said car probably has a weak fuel pump. My funds may not allow me to fix the issue for another couple weeks

A mis fire puts unburned fuel in the exhaust and can overheat and damage the catalytic converter.

Try another mechanic, I doubt a weak fuel pump would cause a misfire consistently on the same cylinder.

BTW is this a 1968 Cortina with 145,000 miles?

How about telling us what the car is, make, model, year, mileage, maintenance history etc.

What if the misfire is because an injector isn’t injecting fuel?

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It’s not perfect, but most manuals tell you to shut off the engine if the CEL is blinking, to avoid doing damage; but driving with the light on is OK.

You might have leaking injector. Pour a bottle of Techron cleaner into your gas and give it some time and miles to maybe clear up the problem.

Is that what the “lean condition” means? I’d think too little fuel wouldn’t necessarily mean none.

It might. Cat at risk. Also could overheat and damage valve etc. Could be benign for the most part too. Best to get it diagnosed asap imo.

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A bad fuel pump would cause a misfire on all cylinders randomly, not just one cylinder.
Likely causes:
Intake manifold gasket
Fuel injector
Fuel injector wire (personal experience with this one)

How do you know it’s a misfire due to a lean condition?


“Lean” means that there is either too much air or not enough fuel. Instead of replacing parts, this can likely be diagnosed quickly by checking fuel trim values on a scan tool with live data. You may also have more than one issue, like a bad spark plug and a vacuum leak for example.

Again, “lean” doesn’t necessarily mean no fuel. It means an improper mixture. I agree with @Dappersworth that it’s not the fuel pump. Bad or leaking injector is more likely.

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