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Old 11-07-2019, 02:40 PM   #1
Barmac_rallye
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Default Lightweight flywheel on 03 WRX. Any issues?

Hello all,

I recently had my clutch go and so I got a new Exedy Stage One kit and Lightweight Flywheel.

I was talking with a shop on a separate issue with the exhaust and I mentioned replacing the clutch and flywheel with the Exedy. The shop associate stated in passing that I should not do the flywheel because it will cause misfires.

I have never heard of people having issues with the lightweight flywheel unless they had done other modifications on the engine (lightweight crank for example). Even after scouring the forums, I haven't seen anything about problems or even cars needing a retune afterward.

Has anyone had issues with their bugeye after switching to a lightweight flywheel? I have a 2003 WRX with an intake and 2004 STI turbo and injectors.

Any help would be wonderful. My car is almost back on the road and this is making me worry.
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Old 11-07-2019, 04:27 PM   #2
Breticus
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You should have no issues running a lightweight flywheel. I am running one and it is totally fine.
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Old 11-07-2019, 04:40 PM   #3
snow_bound26
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Some people have had problems with lightweight flywheels throwing misfire codes. It is actually well documented. Just no one really knows why it happens. Lightweight pulley and flywheel have more of an issue when used together. Flywheel by itself it seems it depends. Some do and some don't. The lighter you go the more likely it is to happen.
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Old 11-07-2019, 07:59 PM   #4
Barmac_rallye
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Quote:
Originally Posted by snow_bound26 View Post
Some people have had problems with lightweight flywheels throwing misfire codes. It is actually well documented. Just no one really knows why it happens. Lightweight pulley and flywheel have more of an issue when used together. Flywheel by itself it seems it depends. Some do and some don't. The lighter you go the more likely it is to happen.
What’s more i found a video from Exedy where they do a stage one and flywheel install on a bugeye. I think maybe the shop associate was speaking in generalities since I have found mixed evidence of issues with LWFW but only when use with different cams and tunes. Otherwise, problems arise with much lighter flywheels
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Old 11-08-2019, 04:24 PM   #5
saaiello21
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I ran lightweight Exedy flywheel and stage one disc for almost 50,000 miles on my bugeye and never got a misfire code. On my 2011 WRX running the same stage 1 disc with an ACT lightweight and that hasn't thrown a code either. I think it only happen in cases that the flywheel is a super lightweight one like below 8lbs. I believe the Exedy is abound 12lbs.
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Old 11-11-2019, 02:26 AM   #6
Shik
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I had an ACT Street lite flywheel in my kid's 2002 WRX. Stock crank pulley. From the day we installed it to the day we swapped in a 6 speed, it threw a misfire CEL. No misfire codes before or after the flywheel.

I could be wrong but I think SOA offered an ecu reflash way back when that helped with the overly sensitive crank angle sensor. The ecu keeps track of the crank speed in between each cylinder firing. If the crank slows down enough inbetween two cylinders firing, it triggered a cel, as it would assume the last cylinder did not fire.

The lightweight flywheels do the same thing to the crank speed, although to a much lesser degree. Still, the early wrxs were super sensitive to this and were updated later on which is why you almost never hear of newer WRXs having the issue. Not sure if it was just a 16 bit ecu thing or what. And again, I'm thinking there was a reflash that helped with this but I could be thinking of something else. That was many years ago.

FWIW, the cel was worth it as I loved the way the car felt with the flywheel.
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