Weird engine vibration after car runs a few (~3-5) min. HELP!!!

[jesterbot]

Ok here's the deal... last week I installed my SAFC, this weekend I installed the Walbro 255 - everything seemed fine and it ran well.

This Monday, I installed a full UICP, from TB to SMIC - Again, that went without a hitch. However, since the UICP install (could be unrelated though), I've gotten this weird vibration problem.

When its been sitting awhile and I start it up (cool), it idles and revs smoothly like before. After it warms up a bit, I get some pretty bad (definitely noticable) engine vibration, especially as it revs through the 1000-2500rpm range. Like if I'm cruising at 3000-3500, and drop to neutral, it will vibrate like I'm going over a heavily textured road when the rpms drop through that range. Any ideas on what may cause this???

Any solutions?


Thanks guys!

 

[1stGenGSX]

sounds like maybe misfiring, but i would think you would notice that at idle as well.

 

[jesterbot]

Well it might be at idle too... just not severely if so. I mainly notice it in that rpm range. The more interesting note to me, was the fact that it runs smooth when cold, and only does this when warmed up - could it just be a misfiring issue? Plugs/Wires maybe?

 

[HyperGSX]

I have the same problem, i am misfiring in cyl #4 due to an oil leak.