Shawn W

Ok so here's the deal. The shop just finished putting my motor in my 94 Z28. Here is a list of the mods that were done at the time:

Eagle crank
Scat 4340 Rods
Speed Pro pistons
CC305 cam
Comp valve springs
Comp hardened pushrods/ Guide plate
Crane Gold Non- SA roller rockers
Lunati Timming set
Mac Headers
New plugs and wires.

Heres the problem. The car starts and idles fine. Whenever you drive it though it Runs pretty good untill it gets warmed up. After it gets warmed up it runs like absolute crap down low. Under 2500 RPM's it has no power and pops back through the intake. It doesn't do any of this when it's cold.

Is it the cam that is making it run ****ty? I am on the stock tune with stock injectors. Stock fuel pressure

Or is the opti crapping out when the car warms up? My Mechanic said the cap and rotor were good on tmy opti but couldn't verify for the rest.

I have no SES light either.

Tell me what you think.

Thanks
Shawn

97Z-M6

is it still a 350 or is it a 383 or other if it is it may be to small injectors, and if the duty cycle is to high on the stock injectors it could be because of tuning. you need to get it scanned and check for codes the get the tunning done.

Camaro_Maniac63

I think you definitely need some tuning done on that car. I have the Hotcam in my car with the stock tuning, and my car pretty much does the same thing, although it is not as bad as what you are describing. Tuning does wonders for the lower RPM power, I have heard.

Shawn W

well i am waiting on PCMFORLESS to get here. I put in all the specs for my car. How much do you think that will help?

Also my car is a 355CI

they said they ran a scan on it and everything showed up normal

thanks
Shawn

Camaro_Maniac63

Tuning is a must for cars with different cams. Sometimes it gives you a lot of hp, sometimes it doesn't, but either way, it improves driveability a lot. I think with your setup, you might want to get it dyno tuned rather than mail-order tune. But then, I've heard Bryan does a great job. I hope he can hook you up and get you going nice and smooth. Nice combo you got in that car by the way. Good luck.

94 Roadhog

Yes!

Shawn W

thanks man, I would go ahead and get it dyno tuned but i still have heads and a higher stall converter to do. I am hoping the mail order tune will get me by for now. I have heard great things about PCMFORLESS. So you guys think it is more the tune than the Opti? I mean the Opti worked fine on my old engine and it didn't get any damage or anything while it was off.

I guess when the engine warms up and goes into closed loop the cam is just kicking the computers ***?? What do you guys think?

Thanks again
Shawn

playaz28

all my extensive limited experience tells me that it is your PCM that needs tuning.

Fastbird93

I had that exact same problem on my Black T/A about 3 years ago. Ran fine cold, but once it warmed up, started to miss, pop, hesitate, all below 2000-2500. It was the Opti.