While accelerating has a jerking/pulsating?

SEBASTIANFROMNJ

MEMBER
2012 SUBARU FORESTER
2.5L
4 CYL
4WD
AUTOMATIC
130,000 MILES

It almost feels like a transmission slip but it’s not the transmission slipping. Transmission was replaced 2x to verify, the first trans they had was burnt from low fluid driving from a leaking line and wasn’t shifting properly. Unplugging the MAF sensor makes it stop pulsating while accelerating, tried substituting the sensor did not work, had oxygen sensor codes both were replaced, all codes are gone, car is still jerking while accelerating. Plugs and coils were replaced. Idle feels a bit rough and sometimes has a long crank. Other times it starts right up first try. Starter fluid does not help it start if it’s long cranking. Any ideas on what to check?

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,758 POSTS

Hi,

If starting fluid doesn't cause it to start, it sounds like you may have lost spark to the spark plugs. When this happens and it has a delayed start, check for spark.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/how-to-check-for-ignition-spark

If you find there is no spark, my first suspect would be the crankshaft position sensor is failing. Take a look through this link and let me know if anything mirrors what you are experiencing:

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

Let me know.

Joe

Note: This sensor can fail and not set a diagnostic trouble code.