Just as the title says.... I have a violent shudder upon full boost/load. I am currently in the process of tuning the car. The mods include a walbro lph400(e85 compatible) 1450cc injectors, speed density conversion, gt3076 Full race single scroll kit. intercooler, piping, tial bov/wastegate 272's, and running E85 fuel.


Anyhow Jester tuning is doing the remote email tuning.

The problem is if I go above 50-60% throttle. It will boost maybe 20lbs and have a violent shake on the front end. Almost like wheel hop. literally shakes the whole front end...

If I go 40-50% throttle it pulls clean to redline. I thought at first it was just fuel/boost cut. Maybe I was hitting too much knock/load. and the engine pulled timing and everything...

but I'm starting to think that it is maybe the front diff? or clutch? or worse?

If you have any suggestions let me know. Maybe its just because it is not fully tuned?....

I plan on replacing the clutch shortly but would like to get this solved. So I am open to suggestions.

Thanks ahead of time.

 

check your spark plug gaps. sounds like you're just blowing the spark out.

 

Sounds like it could be your clutch, what's the tach do when this happens? Do a pull in 4th gear and report back.

 

nvm...

 

Ya I purchased the car super cheap as it wasnt running. The rpms do not jump up.

In my last evo when the clutch went in 4/5th gear and load the clutch would slip and the rpms jump. So I dont think it is the clutch. I will check the plugs today.

What does a bad diff do? Unfortunately Im 3-4 hours from the closest evo shop. So I was trying to figure it out without making a long trip.

 

Its almost as if the diff is messed up and under full boost/load it is messing with the power delivery maybe? And causing the car to shudder violently.

What about fuel cut? As Im still working on the tune with Jester.

Im putting a new clutch in as soon as I get a day free. So fingers crossed the clutch is the culprit. Is there a way to check if my diff is functioning correctly? Put the car in the air and go through the gears?

 

It was the clutch. Holding enough in 2-4th to just jerk. But full boost in 5th made the car jump up in rpms... threw the new clutch and flywheel in and am now at 30psi on e85, running good. : D