'06 Runs rough only when in third gear

[BrentRN]

I have started to feel a roughness in the engine when accelerating but only in third gear. It is worse when the engine is cold and is less noticeable when the engine is warm but is perceptible. In fifth at highway speeds all seems fine. There are no engine codes thrown.

The car is a 5-speed with 107K. I bought it in 2010 with 30K. Rocketchip at 45K. New TB at 80K. New clutch at 90K. All oil changes with recommended oil at 10K intervals. Fuel filter changes every 20K. It has run perfectly since I bought it. Any ideas what this could be?

 

[scrichy84]

Did you change your tranny fluid when you did the clutch? The fluid capacity has to be pumped in as it will run out the filler hole, unless the fluid was changed with the tranny out of the car.

As it is an issue isolated to third, I would start there. My 2 cents.

 

[BrentRN]

Did you change your tranny fluid when you did the clutch?

No, the tranny fluid wasn't changed. Thanks for the suggestion.

Today I noticed it in third and fourth but only when accelerating and between 2000 and 2500 rpm. The roughness could almost be described as a "bouncing" of the engine. It that an engine mount issue?

 

[D-Cell_Mekanick]

Have you inspected for cam wear?

 

[D45014]

2x on the cam.

 

[BrentRN]

The problem turn out to be a bad fuel filter. The third and fourth gear issue was because I was accelerating and I guess not enough fuel was passing through.

I cleaned out the canister, put in the new filter, filled it with half Power Service and half diesel, primed it 3x before starting, and now it runs great.

 

[scrichy84]

Cool! Glad you figured it out!