Help Needed - Sick snake? Dyno Curves Within...

[Janni]

The NC VCA did our second annual Dyno Day in Greensboro, NC last month and Henry and I dyno'd both our cars. The ONLY difference in the 2 cars is that my car has K&Ns and smooth tubes. Everything else is identical. Both 1996 coupes, only 47 SN's apart. See graphs below:

Janni's Car...

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Henry's Car...

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Question 1 - note the red line in Henry's run - the car almost shut off and then came right back on. It happened sevaral times on the track at the Viper Days finals as well. Does anyone have any ideas as to what might cause this?? Any suggestions on ways to diagnosis this further??

Question 2 - note the peak power difference in the 2 cars - its about 40 HP!!! (Ignore the 419.4 listed as this is an anomoly). Smooth tubes and K&N's might account for 10 to 15 HP - where is the rest of the difference?? Both cars are identically set up so what gives????

Any suggestions would be greatly appreciated...

 

[Chuck 97 GTS]

Janni, there is a TSB for 96 and 97 cars that might explain problem #1:

# 18-32-97 - Drop in RPM/perceived misfire at 5500 RPM

Your Viper tech could probably tell you the specifics regarding this problem. As far as #2 goes, do the two cars have a significant difference in milage?

 

[Janni]

Thanks Chuck - Tom Sessions is going to see if we have the latest level code - I think we do and I thought that RPM issue was a 97 only.... I am almost certain we've had the computer reflashed when we first got the car or when we had a bad oxygen sensor. Regardless, Tom said he'd meet us next weekend in Charlotte at the AutoFair, bring the DRB and check our version (isn't he too good?) and then, if we do have the latest version, he and Henry are toying with the idea of running a copilot on it and go back to the Dyno to see if we can record the event. Want his car up to ***** before Mid Ohio - he's not real happy that he's down that many HP from my car. I am now in the process of etching all my engine components so that he and Tom don't start swapping things out while I am not looking

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- which they have threatened to do.

Will keep you all posted. Any other thoughts?