Second shop look at diagnostic codes, shows 2nd cylinder misfiring and replaced dirty spark plugs. Still getting check engine light. Since 1st shop did fuel injection service the 2nd shop said only VM dealer can do fuel injector cleaning to stop misfires at slow speed. What do you suggest?
My car has 124000 miles.
My car has an automatic transmission.
Hi, thanks for writing in. Misfires can happen for many different reasons beyond just dirty fuel injectors. This may be due to a vacuum leak, but it can also be caused by a weak fuel pump (low fuel pressure) or a faulty fuel pressure regulator. It can also be caused by ignition misfire due to fouled spark plugs, bad spark plug wires, or weak ignition coil, a bad mass air flow sensor, a faulty crank position sensor, a faulty camshaft position sensor and many others. The best approach to identifying a misfire due to the broad spectrum of possibilities is to hook the car up to a scanner to download any fault codes that may be registered in the computer. These will further indicate more specifically what the cause of the misfire may be. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.