So I think I made a significant discovery in my quest for this ever-elusive hot-restart throttle response...

And it had nothing to do with AE fueling.... it seems to be related to (of all things) the CCP.

A while ago, I was noticing this weird behavior where (particularly after filling up the tank) that I'd get these sporadic instances of the AFR gauge going pig rich (as in the gauge fully pegged rich) for a split second at a time while cruising at low throttle. It'd be accompanied by engine surging (so I knew it was real, and not a gauge or sensor issue). I ended up tracing the problem to how I had my tank venting system set up, such that I think the engine was literally taking gulps of fuel through the CCP system. Long story short, I modified the venting system a bit and solved that issue.

But it alerted me to the significance of the CCP system's effect on fueling.

So I started thinking about what might be non-ECM related that could be going on with this hot-restart thing. I thought about what's going on with a car sitting in a parking lot for 20 minutes before starting it back up, and it occurred to me that I'm probably getting a significant amount of fuel vapor build up in the tank. If (upon engine restart) that vapor is being consumed by the engine through the CCP system, it could be the "immediately available" fuel being delivered, (and in perfect vapor form to boot), facilitating the razor sharp throttle response.

The last few days I've been paying attention to the CCP system in Tunerpro RT on my drives and I started noticing the throttle response is the sharpest when the CCP duty cycle % goes to 100% the fastest. It's the damndest thing.... I would have never guessed the CCP could have that significant an effect on engine performance. When the CCP duty cycle had a very slow ramp rate, or peaked at say 25% or something like that, the throttle would feel just a tad more mushy.

The thing is, there are so many parameters in 8D governing the operation of the CCP, it's no wonder the duty cycle seems to be so random. The CCP duty cycle seems to be all over the place as what duty cycle you get vs conditions under normal driving.

But with all this in mind, I went through and set the CCP parameters such that the CCP duty cycle goes to 100% as soon as I get on the throttle at all times. Also not allowing the ECM to modify the duty cycle based on INT or BLM. The fact that GM was adjusting the CCP duty cycle based on INT and BLM seems to indicate the fuel vapors coming through the CCP are not trivial to the A/F mixture.

There's one table governing CCP duty cycle vs calculated airflow along with a host of scalars and switches.

Factory AUJP has the minimum TPS% set to 1.5% for activation of the CCP, but I kept that.

In any event, this all had a surprisingly significant impact on throttle response. I would say if my throttle response before was 95% of where I wanted it to be, I would say this change to the CCP got me to at 98-99%. It remains to be seen if this holds for the long term (I've been fooled before on what I thought the fix was). But it seems promising at this point... the closest I've ever been to solving it to date.

 

Man, I would have never in a million years guessed that the CCP system can have such an effect on throttle response. And the consistency of it from one run to the next... that's the other thing. I've read about people's experiences with the 7730 (and in particular with Minirams) noticing some variability in performance from one run to the next, with no other changes to anything.

I've had the car out now 5 times since I made that change and the throttle feel is 100% identical every time. Ordinarily you'd be able to detect a minute amount of variability...

That one day last week I had just happened to see the CCP duty cycle going from 0 to 100% instantaneously during a period of extra-snappy response and low and behold that seems to have been the ticket... and then that snappiness seeming to get a little squishier when the duty cycle changes became more linear...

Once I forced that instantaneous behavior into the calibration, that was it...

Mind-boggling...

 

There really must be a significant amount of fuel coming through the CCP as a vapor....

I originally had my AE Delta TPS Scale Factor vs TPS set to 1.04 at 0-12% TPS. Basically when my TPS is 12% or below, I tell the ECM to scale up the AE delta MAP PW by 4% (to smooth the throttle tip in).

I was able to reduce this factor down to 2% and not lose any performance or throttle response.

I'm still in shock that the CCP has this much effect...