Engine vibrations at low speed (stop and go traffic)

[supercow2610]

I have 2010 Legacy with 2.5i engine and 120k miles. Recently I upgrade to WRX 17" wheels and 225 55 17 wheels, KYB struts, 2013-14 front springs (no time for rear yet).

 

I notice the car rides smooth and engine vibration is relatively low most of the time except for when it's traffic (i.e. stop and go on freeway where you go slow down from 50mph to 10 quick and have to pick up speed and slow down again). I notice that the engines shudder more often and can feel the vibrations. Gear ratio changing isn't smooth either.

 

Does that mean the engine mount needs to be looked at? Or it's just the nature of automatics or is there something else to it?

[supercow2610]

I had the wheels re-balanced today and apparently the front driver was slightly off according to DT tech guy. This "slightly off" once fixed makes braking much more reasonable and the car vibrations in my other thread is pretty much reduced to minimal. "slightly off" felt like an underestimation.

[Timothy.B]

If you're on the stock wheels, I had balancing issues with mine. I would go to a regular tire shop and they would say they were "balanced within spec" then I'd get on the highway and it'd be a paint mixer. So I'd have to pay out for a RoadForce Balance at the dealer and it'd be fine. This happened with both the stock Bridgestone tires and my new Yokohama winter tires.

 

I got my new Enkei's and Michelin tires, went to a regular Conrads (same one that I had issues with with the stock wheels) Car drives smooth as can be. He said they took hardly any weight to balance. I feel like these stockers can warp and bend in odd ways that tire shops have trouble balancing out.

 

Edit: I see your first post now. Kinda odd for new wheels. Vibrations could be a number of things.

[supercow2610]

If you're on the stock wheels, I had balancing issues with mine. I would go to a regular tire shop and they would say they were "balanced within spec" then I'd get on the highway and it'd be a paint mixer. So I'd have to pay out for a RoadForce Balance at the dealer and it'd be fine. This happened with both the stock Bridgestone tires and my new Yokohama winter tires.

 

I got my new Enkei's and Michelin tires, went to a regular Conrads (same one that I had issues with with the stock wheels) Car drives smooth as can be. He said they took hardly any weight to balance. I feel like these stockers can warp and bend in odd ways that tire shops have trouble balancing out.

 

Edit: I see your first post now. Kinda odd for new wheels. Vibrations could be a number of things.

 

Thanks for the reply. These wheels are ysed wrx but i checked before buying and theyre not bent. I also brlught them in the shop before getting tires to make sure. I might have to look into what machine discount tire uses to balance. For now, the ride is relatively smootth. However, i can feel engine. Ibration at certain rpm especially low speed. I also feel vibrations, most noticeable when i keep the rpm at around 1800 or 2000. Feels as if the tranny is not sure what to do. Any insight?

 

I feel like the cvt is only smooth at high speed ie 40 and above.

 

Thanks for the tip

[supercow2610]

A little update on the engine/car vibration. The vibration is really shaking the car @ 1k-1.5k rpm, more so 1250rmp. If i push the engine out of that rev range, the shaking stops completely.

 

Next, when i notice the vibration, I switched to "manual mode" and shift 1 level down. Vibration gone and the car rides smooth. I was maintaining speed @ 30-35mph (fearthering on the gas pedal) with rpm hovering @ ~1250. When i switched to manual, gear ratio is set at 6 and the car shudders. When i pressed to 5, the shuddering stops, rpm goes up to 1800-2000.

 

My hypothesis is that the car was tuned to be fuel efficient to the point of being flawed. It's tuned to go to higher gear ratio asap and that situation confuses the heck out of the ECU.

 

Any body knows tuner in Seattle region that can work on the 2.5i?

 

Thanks

[supercow2610]

This thread from the OB guys describe the problems im experiencing quite well

 

http://www.subaruoutback.org/forums/138-gen-5-2015-present/219770-shudder-cvt-during-mild-acceleration-shifting.html

 

I might try 89 OCtane next fill

[Timothy.B]

I do notice a slight shudder at times on my 3.6R. HumbleRumble on here actually went to the dealer and I believe they tested 3 other vehicles and found the same sort of shudder sometimes when taking off.

 

I'm not sure what my tuner does with the CVT but he may be able to tune it to perform more smoothly. I haven't driven any of the CVT's for comparison though.

[supercow2610]

To update and pull an old thread, my car shake fest has been fixed.

 

2010-2012 2.5i cvt uses t belt. I was told by the dealer TWICE that the engine uses t chain. So I have been ignoring the belt maintenance and racked my head for the past 6 months.

 

Finally i checked the service manual and lo and behold "t belt maintenance" at 105k miles in the service maintenance schedule book. The car was 30k overdue.

 

I took the car in, have the belt replace, interestingly i also had to tell the dealer to replace pulleys (they dont replace them, just inspect per reccommendations??).

 

They also noticed that my ac belt, which was replaced at 90k, is worn out. This is an interesting point.

 

Now the car drives like it supposed to. Steering is better, no more issues with braking, no more engine shudders. The only stumble/stutter/vibration is from the cvt which is very subtle. Rpms also stay lower and the car idles smoothly.

 

So check your belts if you have similar issues to me.

[ehsnils]

Subtle stumble/stutter could also be an indication that the spark plugs needs to be replaced.