A year ago I did a dyno on my car and it showed the constant miss that the engine has had since day one. Of course the Dealership says there is nothing wrong with my car. Here is a dyno from that day.

I added an LS6 intake, 1.8 roller rockers & TPIS longtube headers a few months ago and felt a flutter and loss of power on the very first test drive out of the shop after the install. I drove the car for a month or so just to see if the flutter would go away. While testing the car at vertain times it has even bogged and fell on its face while at WOT. That is something it has never done before. Since then I have had expert help with a MAFT install and endless traces with a Ease program. A Hypertech 3 has been loaded up and now all of my Fuel #'s, timing, O2 sensors, etc, etc.... have been optimal for quite some time I decided to dyno the car on Saturday so I can see how the car runs. Here is a copy of that dyno from Saturday.


My guess was that at 5600 the car started cutting out and I was only off by 100 rpms... In the last dyno the power holds on till redline and even though the car cuts out :rolleyes: each run is basicly pasted on each other. This time I am loosing major power after 5600 and it does it every time the same way... :(

So my question is... do you think that the valve springs need to be changed? or is this computer related? I am leaning more to the springs myself. What type of springs should I get?

Any help would be appreciated. :)

vetterdstr :cheers:

 

The miss that I have had in my car has been from day one when I bought it brand new. The engine has an intermittent miss and is not a steady one that I can attribute to a cylinder or valvetrain problem. Take a look at the first dyno... do you see the gaps in the run? some are very small and one is very big. 18 C5's dynoed that day and my car was the only one that had gaps in the run from the car cutting out.

When the car was new and had no Mods I took it to 5 dealerships and they checked the car out completely (with the tech 2) but found nothing wrong with it. I have changed the plugs and wires twice now. The new Pushrods were installed with the Crane Roller Rockers and are not bent nor were the OEM rods that were removed at 18,000 miles.

Even with the OEM Miss that my car had it still had good dyno runs. Look at the first dyno a year ago. You can see the 3 runs that are pasted over each other and the curve and lines are good. Pulls right to 5000 and holds flat till 6200. Now it pulls hard to 5700 and drops off everytime.

I am not concerned about the Factory Miss with my car as I know only a Tuner like MTI can fix it. For now I would like to fix what is wrong with my car regarding the 5,700+ power loss.

Any other Gear Heads willing to give me any advice here?

Today I am ordering a set of springs, retainers & roller Lifters. I am still interested in any information that one can give regarding the Dyno/power loss or what they think may be the problem. I just want to fix it at this point.

vetterdstr

BTW, I have to give Team zr1 a great amount of credit for tuning my car with the MAFT & Hypertech unit. John is a great guy who is always willing to help me out with my car. Thanks again John!! :)