Engine shuddering

NSSCHENKS

MEMBER
2004 NISSAN SENTRA
2.5L
4 CYL
MANUAL
131,000 MILES

I recently had my starter and battery replaced at a mechanic for my car listed above SE-R Spec V (+/- 131,000 miles).

While it now starts easily, all of a sudden the whole car shudders and vibrates (seat, steering wheel, etc) even while sitting idle. When I accelerate, the check engine light comes on and blinks. I’ve only driven it for all of 5 minutes from the mechanic to my parking spot. I didn’t notice the engine then, but today when I moved it the problem occurred.

I’m not sure what’s going on, but I’m quite suspicious. I know it’s an old car, but my engine did not have this issue before I had the starter replaced. No shuddering and no check engine light, just a faulty starter. Is it possible the mechanics screwed something up when they installed the starter? I ask here because I don’t want to take it back yet and have them diagnose unnecessary repairs or charge me more to fix this new problem.

Any ideas what this might be? I haven’t had a chance to do a diagnostics check on the engine yet but will add the codes when I do. Thanks!

3 Replies

CARADIODOC

MECHANIC
33,873 POSTS

Go back to that shop right away. If you wait, they can legitimately assume this is a new problem. At the very least, the mechanic deserves the right to correct any mistakes he made.

From your description, a good suspect would be a spark plug wire became disconnected. The flashing Check Engine light means you're supposed to stop the engine as soon as possible to prevent overheating and damaging the very expensive catalytic converter. It's flashing because too much unburned gas is going into the exhaust system. That would result from a disconnected spark plug wire, but there are other potential causes too.

It is even possible this really is a new problem. We hate when coincidences like that happen, but if something is going to fail at a certain time, that could just as likely be as the car is leaving the shop as at any other time. Worn spark plugs can cause this shaking too, and that isn't anything the mechanic could have caused. Also, if the engine ran fine when you left the shop, then it started the shaking hours or days later, that too would point to this being a new problem. We can make better generalizations once we know what the solution turns out to be. Please keep us updated.

These articles might give you more ideas:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

https://www.2carpros.com/articles/vibration-noise