engine vibrating under boost, no leaks, HELP!!

[994g63T]

I have a problem with my engine slightly vibrating under full boost. I can drive the car around town and accelerate normal up to speed, but when I give it hell, the engine starts to vibrate slightly and it seems as if something is holding it back from gaining any more power. I have a 2g GST, I have checked all of the vaccum lines and charge pipes-no leaks. I have replaced the MAS, coil pack, transistor, wires and plugs. I am running out of solutions. I am only running at 13psi, stock injectors, walbro 255 ful pump, with a evo III 16g turbo. Please help!!!

 

[Newlogics]

I have a problem with my engine slightly vibrating under full boost. I can drive the car around town and accelerate normal up to speed, but when I give it hell, the engine starts to vibrate slightly and it seems as if something is holding it back from gaining any more power. I have a 2g GST, I have checked all of the vaccum lines and charge pipes-no leaks. I have replaced the MAS, coil pack, transistor, wires and plugs. I am running out of solutions. I am only running at 13psi, stock injectors, walbro 255 ful pump, with a evo III 16g turbo. Please help!!!

This sounds like classic untightened coupler scenario. (looks like it's on, but lets air out under boost. If you're 100% sure intake piping is intact, then you're possibly flooding your engine with fuel.

Oh, and one more thing. Make sure your positiv clam on the battery is tightened (both nuts, inner and outter, the one that holds two white wires from the alternator).

 

[alex99gst]

Your engine vibration could be due to old motor mounts, but if you are running a 255 pump without any way to regulate fuel pressure then it is almost certain you are running pretty rich if not extremely rich. I think an adjustable fuel pressure regulator is top priority for you in order to make sure you arent giving the engine more fuel than it wants like Newlogics said.

 

[Precision]

I have seen in a few occasions where a tune up is needed. I would first check the prestated i.e. IC piping and FPR, and then pull out your spark plugs and inspect them. It is a possiblility that you are running so rich that you are repitivly fouling out your plugs.

 

[pneumo]

Are you still on the stock clutch? Does the vibration happen more in the higher gears? A good clutch that's being overpowered will cause a vibration.

 

[Eternalsolitude]

I'm assuming this is all happening with the clutch fully disengaged.

Look into an aftermarket FPR for your 255, or look for a 190lph somewhere, as you will be able to use the OEM FPR with a 190. As of now the 255 is a bit of overkill, and unless your going balls out, then it will be even with some modification.

 

[kottyking]

I agree w/ the fpr. Check into this.

 

[alex99gst]

Any news on your plans for fixing this or if you have fixed it?