Originally Posted by Dem768
Great- what are your vacuum readings at idle with 12 degrees? Are you saying the sacrifice I need to make is in vac and idle speed?
On the topic of "Idle" cells, are you suggesting that this is causing my revs to shoot up immediately upon starting? I've attached a log of my startup problem.
I'm at about 18-19 in. Hg. of vacuum at idle. And, yes, you sacrifice maximum torque timing in the idle region because of other considerations.
Your RPM zoom looks like a different problem. I suggest you address basic idle performance first. Here's a procedure that worked really well for me in setting up MSPNP9093 idle:
1. Setup idle VE first. I would recommend shooting for maximum vacuum in setting up idle VE because it is a good, non-noisy signal at idle conditions. It ends up being ~stoichiometric, but it is easier to set than using AFR. Use the following steps:
a. Change Idle Control Algorithm to "PWM" and "Warmup Only." Set your minimum duty cycle to 19 and your "Idle Duty at Upper Temp (DC)" to 19. What we are doing here is eliminating variables and putting the idle air control valve under your direct control.
b. Start the car and let it warm up. You should notice that once the "Slow Idle (Upper) Temp (F)" is reached, your idle duty cycle should be fixed at 19.
c. Now, adjust your idle screw to give you an RPM that will keep the car alive while we mess with idle area VE. 1000RPM should work fine.
d. Now were going to find the best VE for your idle, knowing that all other variables are fixed. Go to your "Fuel VE Table 1" and note your current operating kPa and RPM. We're going to change all of the VE cells surrounding this point so that we get a constant VE without interpolation. In my case, I ended up at a VE of 40. It was a very distinct peak.
e. Once you've found your idle VE, set all of the cells in the idle region to this VE to provide stability for your engine. That would be all cells up to about 35kPa and 1500RPM. Your idle VE should be the minimum VE in your map.
2. Now setup idle timing. Just use something between 10-15 and be done with it. If you want to use spark table switching to stabilize your AC-on idle, then use a lower setting, otherwise just set 15. As with VE, make sure all of your idle cells have the same timing to provide stability to the engine. In addition, adjust the timing in your lowest RPM column to idle timing all the way up to 100kPa to provide constant timing for cranking.
3. With VE and idle timing set, and while still in "Warmup Only" mode, adjust your idle air screw for your target warm idle speed. I adjusted for 900 RPM. The basic idea here is that we are setting the minimum air bleed (consisting of minimum DC + idle air screw). We want the closed loop idle control to be able to add air for loads such as lights, AC, higher outside air temperatures, etc. But we should not be relying on closed loop idle to provide our minimum idle air setting. Note that your idle air screw should be at least a full turn open to avoid large % orifice size changes with metal cooling and heating. If this results in too high of an RPM, then reduce idle timing. You can see how these things are interrelated.
4. With all of the above done, you can now return to "PWM" and "Closed Loop Only" and mess around with closed loop settings to provide recovery from loads. Note that if you don't have big loads like AC, plenty of people are content to just use "Warmup Only." It is simple and stable.
After you get idle stabilized as above, post another recording of your startup RPM zoom.