A very common problem is when a vehicle jerks when accelerating. If your Saab 9-5 is jerking when you press the gas, there are a few common issues that can cause this to happen. These include misfiring, fuel delivery issues, the catalytic converter, and more.
Saab 9-5: Jerks When Accelerating Causes
Your 9-5’s engine is a pump. It mixes air and fuel together and needs a strong ignition of the two to run properly. If any of these three variables are off, you will not have optimal combustion.
If your check engine light is on, the first thing that you should do is scan the computer system and see if there are any OBDII diagnostic trouble codes. You can pick up a scanner pretty cheap. Or, most major parts stores will provide this service to you free of charge.
Here are the most common issues that cause your 9-5 to jerk when accelerating:
1. Misfire
An engine misfire can be caused by a few things. Most of the time it’s going to be the spark plugs or coil packs that are the culprit. A misfire is the most common reason that your Saab 9-5 would be jerking while accelerating.
Here are some common misfire causes.
- Spark Plugs– Even under the best conditions, spark plugs will eventually need to be replaced. Oil on the plugs, the wrong plug, or bad spark plugs can cause a misfire.
- Coil Packs– Your ignition coil, or coil packs, create the spark and send it to the spark plug at just the right time for optimal power and efficiency. When one has gone bad, they’ll usually cause your 9-5 to jerk when accelerating, idle rough, and hurt fuel mileage. Here’s more on diagnosing bad coil packs.
- Plug Wires– Spark plug wires are not as common as they used to be, but your particular model of 9-5 may have them, so they are on the list. A spark plug wire goes bad when it can no longer transfer the spark from the coil pack or distributor properly.
While ignition system is the most likely reason that a vehicle will jerk when accelerating, it is not the only one.
2. Exhaust Issues
All of your exhaust has to pass through the catalytic converter to get to the tailpipe. It is possible for the converter to clog. This is particularly true if there has been a rich air/fuel mixture that has run through it for a while. When it is clogged, your 9-5 will struggle and jerk when accelerating.
You may also notice that it has a “top speed” that is much lower than what you would need to drive on the highway. This happens when the catalytic converter is almost completely full, and the engine is choking on its exhaust.
3. Fuel System
Your 9-5 needs fuel to run(obviously). If one of your fuel injectors is clogged, or not firing properly, it can cause a jerking sensation.
Outside of bad fuel injectors, a bad fuel pump or fuel filter can also cause a jerk while accelerating. When either of these go bad, there is not enough fuel pressure at the fuel rails.
You should check to see if the air intake it blocked with something foreign. Or, if you have a very dirty air filter. Not enough air will throw off the air fuel ratio and make the 9-5 jerk as well.
4. Bad Motor Mount or Transmission Mount
The motor and transmission mounts are responsible for connecting your 9-5’s engine and transmission to the chassis. If one of them breaks, it can lead to jerking when braking, accelerating, or putting the vehicle in gear.
Conclusion: Saab 9-5 Jerking While Accelerating
Good luck figuring out what is causing your Saab 9-5 to jerk while accelerating. Everything described above should cause the check engine light to come on, with the exception of a bad motor/transmission mount. So, make sure you get the trouble codes and take it from there.
If there is anything you would like to add, or if you have a question, leave a comment below. Have a great day.