4500 RPM studder, with info
 

hey guys im still dealing with this rpm studder around 4500. i've posted before and i know there is countless other posts about this problem and they all say its probably a fuel delivery problem. i also just got my car back from the shop's diagnostic and they have came back with nothing!!!

They said the car is throwing no codes at all, checked both computers, the stock and the MadZ28 tuned computer. they also did a test drive with a scan tool and said it's not picking up any misses with the scantool.

Fuel pressure is GOOD, 41 idle, 47 WOT.

I've replaced Coil, Plugs, Wires, Fuel filter. no prevail

I'm supposed to drop it off again next week so they can do some "futher testing" but i dont know what that means.

the owner of the shop is a cool guy and honest as hell so i trust what he says, and he also told me that the studder is only around 4500-4700 then it "drives out of it". which after more of my own testing i found to be true.

i cant think of anything else that could be causeing this besides the opti? and im hopign thats not it? any more ideas??? this is really starting to be a PITA! :mad:

Re: 4500 RPM studder, with info
 

well the guy called me back and said he's 99% sure it's the optispark. everything else checks out ok. he also told me that he wouldnt want to put a GM Replacement in and that he would rather use a DynaSpark system. is it worth the 600$???? can you buy them elsewhere? or should i just replace the bad opti with a new one from GM?

Re: 4500 RPM studder, with info
 

I have exactly the same problem on the 'hawk. At WOT when it hits about 4500 it just falls flat, like someone either took all the advance out of it or cutoff the fuel. However, at slightly less than WOT it pulls hard all the way up to redline. That's what makes it really odd. How is yours at < WOT?

My fuel pressure is good and the filter is new. I've replaced plugs and wires, and am waiting on a MSD cap+rotor. No, I can't step up and pay $600 for a distributor!

Obviously, I'm really interested in what you can find for a solution. Unfortunately, the MSD's have been backordered forever, so I won't be able to test that anytime soon.