So I put a GT1 mild cam in Sof and ever since then when she sits idling for like 20 minutes (enough to get hot) the rpms start jumping up and down and her nice cam sound comes back. It looks like it's the IAC acting up because it's not used to all the changes that were made. I'm getting it dyno tuned next year along with new rear gears, but is this somewhat normal for that to be acting goofy? Nothing else really happens, the oil pressure gauge jumps around a little, but it always flutters a bit anyway. No codes, nothing else. She just starts acting like a cammed car with jumpy rpms.

 

The car is going to run weird until you get it tuned for an aftermarket cam. I know since I am getting a whole new rotating assembly, a tune will be a must for me.

 

Yea this is normal for the stock computer when it has been cammed or any other perfomance mod has been done. Basicly the computer is reacting to the cam with settings for the stock cam and the rich or lean condition at idle is not being corrected so the computer tries harder which is too much and then cancels the commands untill the rich/lean conditions return. Rinse and repeat. That is why the idle jumps. When the car is cold it prolly does not do that much because it is running in open loop which does not take readings from a few of the sensors like the O2 sensors so it does not know or care about a too rich condition it is actually expecting it. Once the engine warms up it runs in closed loop and all sensors are functioning and the computer adjusts the engine accordingly.

Massey

 

Got ya. I figured it was something like that. I plan on getting her tuned, but my bank account needs a break and now I have other issues with her to figure out. I assumed the tune can take care of any little tweaks that needs to be made and adjust any little weird things she's doing because of the changes. As long as it won't hurt anything for now, I won't be concerned about it.

 

I dont think it will cause any harm but if you get alot of pinging you will want to have that tune ASAP or you will damage your pistons and possibly valves. Running too lean can kill cats and o2 sensors (it will melt them both). Keep an eye on your CEL and make sure that you are not getting any knock sensor or too lean codes. If so try to get the tune as quick as you can to prevent the engine from getting hurt.

Massey

 

Yeah I know I need a tune, it's just expensive. This build has me drained. I don't think the cam is aggressive enough to cause a lot of damage, it's only a little bigger over stock. But I'll still keep an eye and ear out for any new noises concerning that. Thanks!

 

Good luck, tuning 3.8Ls can be a $#%@!, read:
http://www.camarohomepage.com/project/part3.htm

"We retained, Z-Industries of Temecula, California, a top aftermarket cal specialist. Z-I's owner, Ron Zimmer, told us that the computer for the later V6s has programming as complex as that of GM's latest stuff for the C6 Vette. The cal for our project was a arduous task, even for a pro like Zimmer."