I just recently bought a 99 eclipse gsx thats an auto and ismodified aftermarket turbo, fmic and all. lately it will build up boost but it kinda stutters at about 3500rpm as its beginning to build a lot of boost and wont go like it should and is trying to when i try getting on it. any idea why this is happening and what the fix is?? any help would be great. thanks Tim!

 

do a boost leak test. Have you done any recent work to the engine or engine bay since this problem started. Sounds like a vac/boost leak.

could also be spark plugs holding you back as well

 

also what is hte car tuned with. How about letting us know what the exact mods are I.E what turbo, what fuel setup, and tuning device. Who tuned it?

 

im not real sure what all is done to the car to be exact and i just got the car last thursday so i havent touched anything with the engine or car. it ran perfectly fine when i test drove it each time and then after i bought it for a couple days and then i filled up with gas and it started acting up on the way back to the house. im not sure who tuned it last but it has an safc that looks to be installed but doesnt power up. has a boost controler i believe it was the pro spec b where you can select hi or lo boost and adjust each by turning the ****. it will run normal if i dont really get on it past 3500rpm it seems but after that is when it studders and just wont let loose .

 

Your gonna have to list all the mods like emonz mentioned for any of us to help. Pull the plugs and see what they look like, check for boost leaks and do u have a check engine light on?

 

What gas did you put in the car? it needs premium or you will blow your motor. 87 or 89 octane fuels will cause the car to studder under boost. How much boost is the hi and low settings?

 

turbo says i believe a 50trim on it. turbo back exhaust with no cats umm front mount IC. there is a check engine light on and on the engine/valve cover there was something that looked to be oil sittin in there on top of it. also i have noticed that above the exhaust is like a black film/dirt type stuff on the bumper that wipes off. to be honest im not sure as how much boost the hi and low are. just has the 2 ***** which can be adjusted from min to max. how do i go about testing to see for boost/vacuum leaks? I use only 91 octane gas just like it says and just like i did in my IS300.

 

well first thing is first. find out what tunning device is in the car. OR take pics of the motor and all the electronic extras inside the car so we can figure it out. is there a boost gauge? you need to know what PSI you are running before we do anything. I suggest leaving it on the lowest setting. Im assuming the turbo is not a 50trim. I assume it has a .50a/r. a 50trim turbo is a turbo that will make 370-400WHP. I ampretty fimiliar with the 50trim turbo as I Ran one on my Evo and mine had a .63 a\r and was BB. They have a non BB version and a .48 a/r as well.

vague details will not help us to help you so we need to put the peices together first. Another thing is if there is oil or water under the spark plug cover you need to take care of that cause if it leaks into the plugs your gonna get a misfire. The color above the exhaust usually means your running rich. Does the car smoke at all , normal driving or hard driving? and what color is the smoke

 

how can you buy a car without even knowing what is in the car. That would have been the first thing that i would have asked. And from what you have been telling us, its still very hard to tell you what the problem could be. With the mods you have it could be any number of things. Youd really need to look at it

 

Get the check engine light scanned.