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Hello
I just bought a used automatic Honda civic 2013 with 160000kms on it. Theres a shudder/vibration felt under light acceleration after it shifts gear. It's like just when it shifts and rpms drop to 1500, vibration is felt like its lugging the engine. As the rpms start to climb past 1700 under light acceleration, shuddering goes away. As long as the rpms are below or at 1500 after the shift and its being accelerated, vibration is felt. If I just floor it, shifts very smooth with no issues. If the vehicle is driven in D3, the engine runs on high rpms hence no vibration felt.
I have drained/refilled transmission fluid 3 times in a row as the old fluid looked dirty. Inspected the motor mounts which were fine, changed out spark plugs but still no luck. Could it be the ignition coils? or anything else I should look at? Theres no check engine light or any logged codes. Any ideas/suggestions much appreciated. Thanks.

 
Rep Power: 133

If you have an EGR valve, a clogged EGR valve and ports can cause symptoms similar to driving over a washboard road when accelerating or trying to maintain a constant speed.
You did use OEM Honda ATF DW-1 correct? What spark plugs did you use?

 
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Is it possible to clean out the EGR valve and ports or do I have to replace it? where bouts is it located?
I have used OEM Honda DW1 transmission fluid and NGK laser iridium spark plugs.Thanks

 
Rep Power: 222

You can try cleaning it. I know on the older civics it was actually the EGR passages in the intake manifold that would get clogged up

 
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So, here's an update. I found the boot from the air filter to the engine intake had two huge cracks. Replaced it (hoping the engine isnt dusted out). Drained and refilled transmission oil the fourth time. Test drove the car and found the vibration is almost gone. I wanna say its still there maybe 10% but most of it is gone. So Im leaning towards cracked boot and bad tranny oil. Maybe there's some wear on clutch discs too since it isnt completely gone. Hard to tell.

 
Rep Power: 222

That would definitely cause some issues, try cleaning the intake sensors, that may help. Pick up a can of maf-safe sensor cleaner at any parts store