Musings on Idle Flare when Stopping
11-05-2016, 10:17 PM
#1
Musings on Idle Flare when Stopping I've been playing with the Idle Cracker enable speeds... below 10mph it's off to allow for adaptive idle routines to kick on. This has helped me when returned to idle and has helped eliminate a slight flare back to say 1100-1200 before idling at 850. With the MAF enabled, I rarely got flare with essentially stock tables for cracker and rolling idle. However in SD, I saw it more. So I disabled the Cracker below 10mph and played in SD mode today to see if I could make it "perfect."
I managed to make the car stall with the A/C on today as I played with the rolling idle tables.
Does anyone have any ideas for how to tune them? I returned them to stock and with just the disable speed kicked up has helped in SD. In MAF or blended mode, the car drives like stock. I just want to tune the airflow to be on point and drive the same in SD mode. When I install the supercharger, I'll ditch the MAF... So I want the car to drive just as well.
I managed to make the car stall with the A/C on today as I played with the rolling idle tables.
Does anyone have any ideas for how to tune them? I returned them to stock and with just the disable speed kicked up has helped in SD. In MAF or blended mode, the car drives like stock. I just want to tune the airflow to be on point and drive the same in SD mode. When I install the supercharger, I'll ditch the MAF... So I want the car to drive just as well.
11-09-2016, 09:18 AM
#5
Moderator
Jake: Looking at the tune you sent me a year ago, your High Octane table has slightly more advance at 1200 RPM than at 1000 RPM. This might be encouraging the engine to stay ("surge") at 1200 RPM and delay dropping lower until the IAC forces it down. Or until the Idle Spark Control Overspeed table kicks in when the Throttle Cracker is disabled.
My 19* Overlap cam (yours is only 6*) has been an extreme learning experience getting it to idle properly, not surge and not stall when stopping. I found it best to keep the Idle and High Octane advance tables constant between 400 and 1200 RPM. With a target 950 RPM idle, I have even experimented setting the High Octane 1200 RPM column 1-2 degrees lower to discourage a similar "flare". While still experimenting, setting the Throttle Cracker Disable speed to 10 mph (and Enable to 12 mph) seems to help prevent stalls when stopping.
I have my Rolling Idle table set to 999 for all values, but as mentioned, have not noticed it having any effect.
My 19* Overlap cam (yours is only 6*) has been an extreme learning experience getting it to idle properly, not surge and not stall when stopping. I found it best to keep the Idle and High Octane advance tables constant between 400 and 1200 RPM. With a target 950 RPM idle, I have even experimented setting the High Octane 1200 RPM column 1-2 degrees lower to discourage a similar "flare". While still experimenting, setting the Throttle Cracker Disable speed to 10 mph (and Enable to 12 mph) seems to help prevent stalls when stopping.
I have my Rolling Idle table set to 999 for all values, but as mentioned, have not noticed it having any effect.
11-09-2016, 08:04 PM
#6
I changed it around a lot. I had set everything at 24 degrees there from 400-1200 upto .28g/sec. It holds at 24 as I come to a stop and it still wants to do it.
I'll play with the timing some more. It doesn't do it with the MAF, in fact, I cant set timing, airflow, whatever to almost anything and it doesn't surge. But SD, I can't get rid of it. And it's because of the 102 TB. If I had stock or 92, I don't think it'd be an issue.
I'll play with the timing some more. It doesn't do it with the MAF, in fact, I cant set timing, airflow, whatever to almost anything and it doesn't surge. But SD, I can't get rid of it. And it's because of the 102 TB. If I had stock or 92, I don't think it'd be an issue.
11-09-2016, 10:12 PM
#7
Moderator
I also have a 102 TB which makes it more difficult to tune. I have a 1/4"+ hole drilled in the plate and still have the stop screw turned far enough I had to mod the TPS to get the voltage down to .5V. Fully warmed up and in Park/Neutral my IAT is in the single digits.
I logged several stalls and was surprised that the air volume went up to .45g/sec; I therefore don't reduce the advance in the 400-1200 range below .45g/sec. Those values might be higher than you need because I have a 6.9L (419ci) stroker and 19* cam.
I logged several stalls and was surprised that the air volume went up to .45g/sec; I therefore don't reduce the advance in the 400-1200 range below .45g/sec. Those values might be higher than you need because I have a 6.9L (419ci) stroker and 19* cam.
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11-10-2016, 09:14 AM
#8
I was dealing with a similar issue with my 92 setup and only 5 degrees overlap ever since going SD. Maf no issue....My tuner helping me Lorenz @ LSxPT was able to get rid of most of it on this last tune. It occasionally will dip or raise 200 rpm then settle in when coming to a stop, but mostly idles right down to 850 smoothly now. I also get a tiny bit of surge around 40-45mph with the converter unlocked holding the throttle steady. Imo it seems like the throttle body is the issue because it is soooo damn touchy. If your toe wiggles the rpms fluctuates. It's by no means a huge deal, the car drives pretty damn good, but I would not call it stock as some might say.
If you want a copy of my tune I can send it over being we have cams with similar overlap and running SD.
If you want a copy of my tune I can send it over being we have cams with similar overlap and running SD.
11-10-2016, 03:53 PM
#9
That'd be cool. Lorentz helped me with my bigger cam. But it was iffy everywhere. This one has been much easier except for that one little glitch.
If you get issues with foot on and surge... Add timing right there. At least that works for me.
If you get issues with foot on and surge... Add timing right there. At least that works for me.