Posted by Steve on April 9th, 2009
Can a bad alternator cause my engine to misfire?
Filed under: Automobile Hell
If your engine is mifiring, there are many potential causes. For example:
- One the cylinders may have lost compression.
- Bad fuel mixture.
- Spark plugs may be fouled.
- HT leads might be shorting out.
- Coils could be damaged.
But something I haven’t read anywhere is that an alternator can cause misfires – and last week, this was proven to be true.
If I started my car in the morning to drive to work, a few miles down the road my car would begin to misfire. To begin with, I suspected the coils – but looking down, it was evident that the coils weren’t showing any sign of shorting out and they also weren’t hot after running.
I thought back to the time I jump started my car and wondered if it may have caused damage to my alternator. I noticed that while the car was running, the interior dome light was flickering – a sure sign of a failing alternator.
My next test was to see if the car could run on its own power – by removing the battery. To do this:
- Lift the hood with the car running.
- Disconnect the negative terminal from the battery. (if the car keeps running, the alternator must be producing some power)
- Try turning your lights and blowers on to see if the car stalls. If it does – your alternator is probably dead.
Based on the results of the test, I went out and bought a second hand $50 alternator from a parts yard. After several hours of drilling through the side of my Saturn (more on that later) I finally managed to connect the replacement alternator.
Sure enough – my car no longer misfires. I’ve also noticed my battery seems stronger too.
