Went to the track and ran some slow times, Mods: 94Z Auto, 2400 stall, Mac Offroad pipe and Y-pipe, CAI, UD pulleys, Nitto's, 3.42's, Taylor Wires, new plugs, MSD Coil, and a Cut-out! Best time was 13.9 at 99.13mph
Previous best without Stall,Nitto's, and UD pulley was 13.6
I logged a datamaster run and the rpm line after first gear was really choppy. And it always pulls out a lot of knock retard, this last run I Zero'd out the knock tables, no help, still slow. Possible Optispark Failure? Can a failing Optispark create false Knock? Anyone interested in looking at the file?? Please help!

 

You could send it to me. I'm no expert but could maybe see something.

Hal

 

How old are your valve springs? Could also be exaust leak.

Old opti could be firing weakly, how old is it? Usually if they are bad they seem to go downhill fast.

 

Saw his datamaster log. Seems he also has a high knock count that coinsides with the power loss BUT he has his spark retard rate set to 0 so no advance is taken out (but the power loss is as though it was still taken out).

He has used race gas but the knock is still there. I gave him the desense circuit calculator and maybe he'll try that. Other then that it appears to be a power problem, not a spring thing. He'll try swapping to stock coil next.

Hal

 

Well, i can't help with that but I am having the same problem. The more mods i put on, the slower my car is. It runs smoth at WOT but it just doesn't have that kick. I just replaced my valvesprings but I didn't regained all my lost power. What are you using to get all the info on the car?

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95' Z28 M6 (bright red)

-Borla exhaust, Edelbrock 1 5/8" headers and Y-pipe, no cat, G2 cold air, Edelbrock 52mm throttle body, underdrive pulleys, Crane Gold roller rockers, 3.73 gears, MSD 6AL and MSD wires, free mods.

-Hurst shifter, Bilstein shocks, Eibach springs, Metco control arms with relocation brackets, Hotchkis panhard rod, SLP subframe connectors, 1LE aluminum driveshaft, 1lE tranny mount, PolyEurethane end links, TA girdle.

 

Zeroed out all the knock tables? I remember there is more than one.

I know my car used to suck at WOT from exaust leak, but it set a SES notifying me of course of my "lean" condition (which wasn't lean of course), and then pulled timing like crazy, but you don't mention a SES hmm...

 

Sneaky, we mostly use a laptop and cable with either Freescan (Free ) or other things like Datamaster that is way nicer and easier to use (that bottom graph saves a HUGE amount of time!) but $95.

Hal

 

I used FreeScan and Excel, but you do have to play with Excel a bit to get it how you like it.

Once I got going though I knew I wasn't going to pay for Datamaster, while its kind of nice to see it all at a glance it just didn't "do it" for me overall...

 

New coil (must have trashed my original) no Major difference. The logged run was not as good, and the temps are much cooler today. But the RPM's still fluctuate.
It does start a little better, and idle a little smoother with a stock replacement coil. Next must be optispark??? Best price so far $270 for a '94

 

Just another idea, hows your grounding strap? Not loose? No corrosion in the area?