I think this is an adaptive idle question but I really want to know if someone can help me determine why the idle keeps surging up and down? the AFR isn't completely out of wack but as it Idles it just keeps going fat, then lean etc... If anyone has a quick second to look at the tune I'd really appreciate it. Other then the CAM its a stock L94 2011 LS GENIV engine. Cam Specs: 235/247, .649"/.629", 113 LSA Thanks!
Your MAP sensor data is wrong. The key on engine off readings are like 118kpa, so you have the wrong linear and offset settings in for that. With this wrong it will not want to run good.
A bunch of other stuff needs to be looked at too once you fix that. Like idle timing, base running airflow
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
Thanks! I've always thought that was weird. My old sensor use to read about 82Kpa when the key was off but when I had to replace the ECU and Harness due to a fire its always read high. I had it tuned and working on the dyno but it never put out the power it did before. Probably because it just ran out of range. Sometimes you just need someone else to say the obvious.. thanks!
OK I got the MAP Sensor configured correctly. It will actually now run in SD mode. I tried doing some more IDLE tuning and it keeps giving me more RPM then I'm requesting. My idle surges up and down, it seems to do well for awhile then all of the sudden it surges? Any idea why it would do that? Do you think this is normal for this size cam? I only ask because this same engine with the same cam seemed to idle better before with the old ECU.
Cam Specs: 235/247, .649"/.629", 113 LSA
Put your stoich back to what the fuel really is. You can't change that value when no station even sells fuel like that. Non ethanol 91+ octane should be 14.68. If it's E10, then change it to 14.1.
I would try bringing your idle timing up into the low 20's and reduce the over/underspeed spark correction to +/- 8 degrees instead of 13-15 to help smooth the idle out.
I'm not sure you are in speed density fully yet either, I didn't see a P0103 code in that log. Change the high/low fail settings to like 2/1hz. Set the two time delays to 0 seconds and bring the high/low thresh counts way down toward zero as well. I'd probably try to tune it on the MAF first, then switch to speed density once it's running okay.
Also if that is no longer a VVT camshaft, don't forget to turn that off.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
I have a bunch of logs from various times on my truck where it does not show the MAF codes, but there is no MAF on the truck so if it runs it's got to be in SD. Haven't fully looked into whether it only happens in the first run cycle after a flash or what's going on, but sometimes they just aren't in the log.
I have been trying to lock out the timing and the throttle position to see why this engine keeps surging? I just don't understand why it keeps surging if the timing isn't changing and throttle is constant why would it keep surging? Is it in the adaptive IDLE section? Also can someone please tell me what table the 17 deg timing is coming from? I tried to lock it all out at 22 deg. Every once in awhile it surges ahead and gives me 22 again which I assume is when it jumps to the main spark table, but where is it getting the 17 deg from? This engine isn't in a car by the way, its on the dyno. It has been on a dyno before and I had to swap ecu's. Now the old numbers don't seem to want to work in the new ECU? Any help would be appreciated.
Oh man, if control systems were that simple, I'd be out of a job ><Originally Posted by Hardluck29
An engine at idle represents an underdamped system...think of a rocking chair that propels itself. It won't settle unless you intervene. That's what the airflow and spark do. They provide the torque authority to control the system. The trick is tuning the gains to yield a stable idle. Don't take this the wrong way, but you may want to bring in an expert on this. Especially without accessory loads - that only makes the amplitude of the RPM oscillation more extreme and difficult to dial in.
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