Got a Prob....I am feeling something in my car that is new. I have been feeling a shudder in my car for a few weeks now. It occurs mainly when I have the pedal halfway down and under half boost conditions, although I can also feel it under WOT and full boost too. It feels like the car is fighting itself to boost then restrict at the same time. I see no change in my boost guage pressures. I can mainly feel it in my hands and feet. I have a Vishnu stage 1. I guess the best way to describe it is if you would push the gas to the floor, then with your other foot lightly tap the brakes several times. I have changed fuel companies a few times thinking that I might have gotten some bad gas with no luck. I have read about this before, but nobody seems to have any answers. Any help would be great.

 

I could be wrong but it sounds alot like misfire or detonation. Any problems before this stage 1?

 

not that I can remember

 

hmm are there any noises associated with the bucking and jerking?

pop's or stuff like knock or pinging (sounds like bb's being dropped into a can)

and what octane fuel are you using?

 

no noises at all....i'm using 91 octane, which is the highes here where I live

 

Well just to rule out octane as a problem could you get some pure octane and mix for like 95 octane? Tetolyne (spelling?) and another one i can't remember are popular choices for octane boosters.

I'm not too familiar with the whole vishnu setup and to help some of the other guys out here can you list your setup with specifics like amount of boost its using, turbo, yadda yadda would be much appreaciated.

Also vishnu is here on the forums you could ask them a question about your problems via pm or something. They are bound to have much better ideas of whats going on than me

 

I also get a small amount of hesitation untill I play with in the turbos powerband for a short while, then it seems to disapear. I have a turbo back exhaust and cobb stage 2, no intake or bov. I had an intake and took it off 6 months later. It smoothed out for the most part, but I still get that hesitation untill it warms a little

 

If you could log things that would really help. Usually very lean AFRs do not happen at partial throttle, even with PTFB issues (at least not that I've heard). I've heard of high EGTs from PTFB, etc, but never heard anyone write about it actually knocking. So, I'm guessing you are having some fluctuation in timing or fuel delivery or fuel quality. Do you always get the same gas from the same company? Maybe you've changed that recently or got a bad tank. Has the weather changed drastically lately, hot or cold? Does this mostly happen in the early morning or at night, or during the heat of the day? This is pretty much why I cant stand these ecu-flash-in-a-box systems. You have a unique car with a unique driving style in a unique climate. Yet you share the same higher performance tune as hundreds of others in equally as numerous situations.

If you cannot log and share data with us (do you have a Delta Dash?) you should call Vishnu. Especially with a reflash and a mild setup like a vishnu stage 1, this shouldn't be happening.

jason

 

My problem happens pretty much any time of day. There hasn't been any dramatic weather changes recently. I recently drove across country and used several different gas companies all with the same result. I hope everone isn't thinking that the car is severely bucking. My wife says she can't even feel it, but I can since I drive it everyday. I am going to contact Vishnu and see what he has to say.

 

Well, just reset the ECU and everything is good too go. The car is as smooth as KY Jelly. Guess thats all I needed to do.

 

By resetting the ECU did you do a re-flash or just disconnect negative battery?

 

That's not very promising as I am wondering if the problem might come back as the ECU "relearns". I we could know what it was having an issue with...

jason

 

I just disconnected the negative batter terminal deris.