The only thing I can think of that's different is that the stepper is moving in large steps on a warm restart. If you increase the "start to taper time" you can really notice it as it brings down the idle in 2 or 3 large steps (each time trimming the idle by about 500RPM). That's why I was thinking maybe moving to 10 steps would help.grippo wrote:The code is working, but its not having the intended effect. Your msq looks fine, I can't find anything in the software or datalog that would explain this. Is there anything you can think of that is different on restart. As an example, there was some lingering warmup enrichment on run 1 which was gone in run2 because iit started at oeprating temperature. But this is only a few percent enrichment. Now if your car was starved for fuel and that's what made it idle lower on the second run, that's a possibility. But it would sound like crap and I'm assuming it idles smoothly on restart. In run 1, if you had let it run another 5 min would the idle go down ?
I very much doubt that going to 10 steps would make any difference since there is no improvement with 5. I will talk this over with Bruce in the morning. He has a board he may want you to try.
On run 1 that's about as low as the RPM was going to get. I have the step table going to 230 steps but I'm pretty sure the stepper motor would have bottomed out at around 190 or so under normal conditions.
The IAC port makes a pretty good whistle...so I can somewhat verify by ear how much air it's letting by. This behaviour is very predictable.. it happens on every warmup.. and the car doesn't need to be at full temp for a restart to bring down the idle. It seems to idle and run fine and so far road tuning is going well. It's also important to note that the IAC does move some during warmup, If fully open at operating temp my idle goes to over 2000RPM.
At any time during that datalog I could have turned the key off and restarted and the idle would have dropped back to 800rpm only to start climbing again as the engine warmed up. It's normal for me to do this 2 or 3 times during a warmup so the engine isn't idleing at 1400+rpm like in the datalogs.
The only other thing that I can think of that might be helpfull is that I've noticed the IAC seems more likely to move during the early stages of warmup (low step count) as the step count exceeds about 200 it doesn't seem like the IAC moves at all. Yet I can tell by the sound of the whistle that the IAC port is letting too much air in and the IAC still has more room to move.