Hello all,

I'm doing a rebuild of a VIN Y 307, but with a few upgrades (Vin 9 cam and a couple of other small details). Nothing extreme. I'd like to keep the stock CCC system and carb, but I have no desire to put the smog pump back in action. I've read that without air injection a stock setup will idle rough and run lean since the computer is expecting to see the extra air. First off, is this true? Secondly, if it is, would an aftermarket chip (like Hypertech) solve this problem?

Thanks for your time, I greatly appreciate it.

 

No, that is not true. The CCC system is pretty stupid and has very little control over the engine. The two most important factors are timing curve and mixture control on the primary side of the carb. The only control the ECU has over the A.I.R. system is to switch between air to the ports in open loop mode and air to the converter in closed loop mode. If the system blows air at the O2 sensor when the computer is in closed loop, the ECU will think that the carb is lean and will incorrectly run it full rich. If you remove the A.I.R. system, then this is a non-problem. The other things the computer does is control the idle speed (via the ILC on VIN Y motors), the evap canister purge solenoid, the EGR valve solenoid, and the converter lockup. None of those are impacted by the A.I.R. system. Of course, don't expect to see any performance changes due to removing the A.I.R. system either. In fact, if you are keeping the catalytic converter, there's a possibility that without the A.I.R. system blowing into it, you can overheat and melt the substrate. Also be aware that the timing curve on the CCC system assumes the EGR is working and provides increased advance at part throttle. Without EGR, these engines will ping at part throttle unless you modify the curve in the PROM.

 

Joe,

Super helpful information there. I really appreciate the insight. I don't expect gains of any sort without the AIR system, it's more of a "why bother?" when putting this engine back together. Duly noted about the cat overheat possibility. I'll keep an eye on that.

Thanks again!