Engine is running but don't sound good

KINZLEY

MEMBER
1998 MAZDA MILLENIA
205,000 MILES

My car runs but sounds bad it will go but it wont go real fast. It has a really bad smell. What could it be. I have done re done the timing thinking that would fix it but didn't. Could it be a vacuum hose or the distributor making it not have no driving power and how hard would it be to fix it?

1 Reply

CARADIODOC

MECHANIC
33,752 POSTS

You haven't included any symptoms, and you're asking about an engine running problem but didn't list the engine size.

If the engine runs unusually smoothly but with no power or increase in speed, suspect a plugged catalytic converter. The clue is you'll hear a hiss at the tail pipe instead of the normal "putt putt". You also won't feel the normal air flow velocity.

If the engine is running rough and shaking, you have one or more misfiring cylinders. Start with the basics like spark plugs and wires. Your Engine Computer should detect which cylinder(s) are misfiring, set the appropriate diagnostic fault codes, and turn on the Check Engine light to tell you. Is that light on? Have you checked the fault codes?

There's a lot of "really bad smells". If it smells like rotten eggs, suspect too much fuel is going into the catalytic converter and is overheating it. If you just have a gas smell at the tail pipe, that is usually related to a sensor problem or a leaking fuel injector. Misfires due to loss of spark will do that too.