shudder at 5Krpm+

for some reason my engine vibrates the car over 5K rpm. it's not making any noise and it doesn't seem to hurt performance but it's annoying as hell. i'm running rich the whole time i'm in boost according to the afm. any ideals? i figure mabye the stock coil can't keep up (and i mean stock all 16 years of it), or it could be lack of fuel? PS putting in 255 walbro later this week.

Do you mean it's misfiring?

Mafix":1x9cblld said:

for some reason my engine vibrates the car over 5K rpm. it's not making any noise and it doesn't seem to hurt performance but it's annoying as hell. i'm running rich the whole time i'm in boost according to the afm. any ideals? i figure mabye the stock coil can't keep up (and i mean stock all 16 years of it), or it could be lack of fuel? PS putting in 255 walbro later this week.

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If your running rich, your not lacking fuel.
*Unless one cylinder is running lean*