aerosmith

engine shaking

4 posts in this topic

hi guys, just bought a 2007 auto wrx. i do not know what mods were done previously by the ex-owner. but a mech did say my engine turbo should be stock, while my exhaust is legal aftermarket. the car feels more powerful than stock, so i guess there was a remap.

the engine was smooth and gear changing was smooth. i went jb to pump full tank of shell v power 97. the drive back was smooth.

today, i was driving, everything was smooth too. but suddenly, at the next traffic light stop, upon idling, my engine shake a lot and this cause the car to shake, it was very noticeable. upon moving off, the shaking went away.

restarting the car does not remove the problem, it shakes in park, neutral, reverse idle, and drive idle. reving above 1k rpm in neutral or any gear removes the shaking. in addition, it seems like my car is not as powerful as before, i am not sure if this is just my mind playing tricks, but boosting feels not as powerful as before. but there are no CEL. another small observation was that if i was boosting at 3.5k rpm, and let go the throttle, they will be a noticeable jerk in the gears, which has not happened before.

i did some research and hear that it might be misfiring, meaning either spark plug or ignition coil spoilt. but those usually comes with CEL right? i just want to throw a guess, is there by any chance, the previous owner tune the car to ron 98 and now that i pump 1 full tank of ron 97, causes this issue? will using a lower grade fuel cause such violent engine shaking?

 

thanks for your help.

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Your suggestions of the potential issues are all very valid, might be a dirty air intake, dirty MAF, or O2 sensor spoiled?

Does it vibrate when the car is moving? Could be engine/transmission mount worn out if the vibrating is not very violent.

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If unsure, best to visit one of the pro subaru workshops to get it diagnosed.

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14 hours ago, snsd555 said:

Your suggestions of the potential issues are all very valid, might be a dirty air intake, dirty MAF, or O2 sensor spoiled?

Does it vibrate when the car is moving? Could be engine/transmission mount worn out if the vibrating is not very violent.

when car moving, it does not vibrate. not mounts worn out.

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