...with the factory PCM if I try and spin it past 7k? Will it just cut out?

I am planning a build and this answer will determine my cam choice.

Thanks!

 

If its tuned you can take it to what ever you have it tuned to. If its stock it will only take it to where the stock rev limiter is which is like 6k in my 96 M6.

 

I don't think that is what he is asking, the stock pcm in our cars "stops" at 7k rpms. He is wanting to know what happens after you rev it past where the pcm can go.

 

If you're going to put a larger cam in and use the stock pcm it's a waste of time, just mental masturbation. Why spend the time and leave all that power on the table? Makes no sense to me.

 

Oh ok. I had to read his question again.

I dont think it would be a good Idea to try and rev the pcm further that its max.

 

It’s all a matter of costs. If I go with the "big" cam, my shift point will be 7500RPM. If the stock PCM can't handle that, then I am looking at $2500 for an aftermarket PCM. That’s a third of my entire build! I can put in a smaller cam if necessary now, shift at 7k and up the cam for and PCM at a later date. But if the stock PCM can be tricked to do so, then I will go with the bigger cam. I just need a definitive answer.

 

Exactly!

 

If you don't mind me askin, why do you state this ? What is so bad about the GM ECM ? I can understand to some extent but that seems to be a very loud statement. I know for a fact that the GM ECM will support over 1000 hp if set up correctly. Now I'm not saying that there wouldn't be any gains if an aftermarket ECM was used, I just don't believe that it would be THAT substantial. It all depends on the situation i guess, but for just a larger cam i don't see it being a "waste of time" or "mental masturbation".

YMMV, of course

And to the OP, I'm not sure exactly where the stock ECM stops or even what happens if you try to go past it. I will ask a friend of mine, how he manipulated his ECM and how far it can be taken.

 

Search the computer forum. I think it has been discussed.

 

I spent a lot of time there and could not get a difinitive answer. I figured I would give it a shot here.

Moderators, feel free to move this to the Computer section if necessary.

 

I have that problem with my car.The cam is suposed to make power to 8k and I can only spin it to 7k.I need to start saving money for a BS3 so I can atleast goto 7700 or so and use all that power I am leaving on the table and maybe trade my 410` in for some 456`s

 

Are you sure it can be tunned beyond 7k?

 

It will rev past 7K but the timing and the fueling don't change from the last cells. The graph is a dyno run of my car past 7K with a stock PCM.



Rich

 

Really! That makes a big difference. Do you think I can bring it up to 7500 without too much adverse affect?

 

My car is untuned. it hessitated with the old motor i had but i had an opti issue. I blew the cap and rotor to hell with my MSD box on a stock cap and rotor with accel coil. I havnt ran my car hard since i only finished the swap last weekend. I'll c where it will let me take it once i get a few hundred more miles put on the new clutch.