Idle Hang and surging at stop
02-25-2019, 03:17 PM
#1
Idle Hang and surging at stop Hi all, been dickin with this since last summer. Not like full time, Just been dealing with the issue and then I get fed up, work on something else while I just deal with it, then start dickin with it again. First, I have the idle hang. You can see it in the log file at the beginning around 25 seconds in. I did a couple of tutorials on trying to fix that idle hang but no matter what I do to the timing it doesnt seem to have an effect on the idle hanging. Note: In order to get the engine to start and NOT die, I had to adjust the throttle plate open slightly (DBC configuration) to get the engine to start.
Second issue, idle surging. When coming to a stop the idle drops, the program compensates and the idle goes way back up, hangs, then drops again then levels out. Kinda inconvenient. Is this related to the idle hang? Too much air?
IF theres anything else you see here, lmk. This is combination of me tuning with the help of Vengeance (who I paid and sent logs to).
Important info - No Maf, IAT wired in (I thinks its in a bad location), 370lsx, 10.8:1SCR, .585/.585 228/232 112 (Otherwise known as Sloppy Stage 2) cam, Premium, Holley hi Rise intake.
Really thought I knew what I was doing here, but apparently not.
Second issue, idle surging. When coming to a stop the idle drops, the program compensates and the idle goes way back up, hangs, then drops again then levels out. Kinda inconvenient. Is this related to the idle hang? Too much air?
IF theres anything else you see here, lmk. This is combination of me tuning with the help of Vengeance (who I paid and sent logs to).
Important info - No Maf, IAT wired in (I thinks its in a bad location), 370lsx, 10.8:1SCR, .585/.585 228/232 112 (Otherwise known as Sloppy Stage 2) cam, Premium, Holley hi Rise intake.
Really thought I knew what I was doing here, but apparently not.
02-26-2019, 01:49 PM
#2
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what throttle body? I"m sort of assuming a holley 92 or 102? I found some stuff I think will help, but would rather give it all to you in one list.
02-26-2019, 03:38 PM
#4
This could be a number of things.
1) whats your tps voltage? is the throttle blade getting hung up? whats your TPS % when this happens? Mine would do it if it got stuck at .8%
2) is your running airflow (idle air) correct? or is the adaptives adding air? if so, when you give it gas, the adaptives disable and when you let off the adaptives come back into play but if the adaptives have to compensate too much, it doesnt catch it fast enough, causing the rpm to dip, catch and surge.
3) how is your fueling? is it spot on? are you sure? make sure that any adjacent numbers in your fueling table does not make any big jumps. 5 numbers different in two neighboring cells is too much. especially in the idle areas
4) timing. some cams like the same or very close to the same timing in the first three rpm range cells. in other words put the timimh at 17 degrees in 400, 800 and 1200 rpm ranges and see if it likes that. i dont like doing that but sometimes it will help.
5) i set my base idle like this: crack the throttle blade open a little bit. crank car. use the scanner to force 0 iac steps. it should still stay running but maybe 100 RPM lower than your target idle. reset the tps and make sure the voltage is in range (.47-.58 is what i set it to) then go through and set your running air flow after enabling the iac motor again.
this should get you close. if you have issues with it learning iteslf bad, then you will need to lower your air adaptives
1) whats your tps voltage? is the throttle blade getting hung up? whats your TPS % when this happens? Mine would do it if it got stuck at .8%
2) is your running airflow (idle air) correct? or is the adaptives adding air? if so, when you give it gas, the adaptives disable and when you let off the adaptives come back into play but if the adaptives have to compensate too much, it doesnt catch it fast enough, causing the rpm to dip, catch and surge.
3) how is your fueling? is it spot on? are you sure? make sure that any adjacent numbers in your fueling table does not make any big jumps. 5 numbers different in two neighboring cells is too much. especially in the idle areas
4) timing. some cams like the same or very close to the same timing in the first three rpm range cells. in other words put the timimh at 17 degrees in 400, 800 and 1200 rpm ranges and see if it likes that. i dont like doing that but sometimes it will help.
5) i set my base idle like this: crack the throttle blade open a little bit. crank car. use the scanner to force 0 iac steps. it should still stay running but maybe 100 RPM lower than your target idle. reset the tps and make sure the voltage is in range (.47-.58 is what i set it to) then go through and set your running air flow after enabling the iac motor again.
this should get you close. if you have issues with it learning iteslf bad, then you will need to lower your air adaptives
02-27-2019, 12:51 PM
#5
It is a FiTech 92mm actually. I did NOT use the china sensors that came with it. I bought Delco IAC and TPS. I also double checked for vac leaks. Additionally,I needed to very slightly set the blade open via screw to get the car to start and idle.
02-27-2019, 05:48 PM
#7
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OK, here is my list of changes for you:
1. Engine - Fuel - Transient: Set min fuel MG to 0.015 and min RPM to 1100
2. Engine - Fuel - DFCO: FOr now, set Enable ETC to 140 C until you get return to idle under control
3. Engine - Spark - idle spark advance (both tables): Set 0 and 400 columns to 32 degrees. Set 800 and 1200 to 18 degrees, set 1600 column to 24 degrees, 2000-4800 to 26
4. Engine - Spark - Advance: Set max speed to 250 mph
5. Engine - Idle - RPM: Set the following:
...a. update RPM Err Time to 1.5 seconds
...b. Proportional Enable RPM Error to 80
...c. Integral Enable RPM Error to 20
...d. Set all your proportional airflow low tables to 0.8 g/sec per 100 RPM from 150 on up.
...e. Set all your integral airflow low tables to 0.2 g/sec per 100 rpm from 100 on up
...f. Set Derivative fast filter to 0.95
...g. Set derivative slow filter to 0.08
...h. Set Derivative rpm low and high tables from 0 through 0.05 to zero. 0.06 to 1.75, 0.08-0.15 to 2.00
6. Engine - Idle - Airflow: Set the following:
...a. Copy your IAC effective area table and paste it 8 cells to the right.
...b. Set your IAC park position airflow to your Base airflow + 33% (times 1.33)
7. After making all these changes, key off, unplug TPS, key on for one minute, key off, plug in TPS, start car and start logging.
Now, if you're interested, here are the WHY's:
I noticed you are very rich on tip out. That is a classic indicator of the min fuel mg set too high. rich idle will cause surging. I verified your injectors are higher flow vs stock. Needs lower min fuel mg. 0.029 is still too high, though lower than stock (0.049)
I noticed when you are coasting down you reach a certain point and your spark suddenly drops 20+ degrees of advance. This is due to the main spark tables still being active when you are idling. I would honestly look at your first two rows of spark timing int he main tables and make sure none are higher than 39 degrees, but I forgot to list it above. Either way, increasing that max speed value allows it to drop into the idle spark tables on coast down.
Your proportional error is too tight, so it's trying to react to natural RPM surge, and the engine responds faster than the IAC. Basically, you need a dead zone where the idle can move around some before any corrective airflow, and then if it gets outside that range, it needs stronger correction.
Needs more proportional support when idle speed dips so it doesn't dip as far.
0 and 400 column idle spark values help provide a natural stall saver.
Your derivative was too active. This will cause the idle to start out stable and then go unstable with time. I saw this a couple of times in your log file.
Your IAC table was still stock, so it was commanding too high an IAC position for the commanded airflow, resulting in the hang followed by surge. Normally on a 92mm I'd go six cells, but since you cracked the screw some, I recommend 8 instead of 6 cells to compensate.
1. Engine - Fuel - Transient: Set min fuel MG to 0.015 and min RPM to 1100
2. Engine - Fuel - DFCO: FOr now, set Enable ETC to 140 C until you get return to idle under control
3. Engine - Spark - idle spark advance (both tables): Set 0 and 400 columns to 32 degrees. Set 800 and 1200 to 18 degrees, set 1600 column to 24 degrees, 2000-4800 to 26
4. Engine - Spark - Advance: Set max speed to 250 mph
5. Engine - Idle - RPM: Set the following:
...a. update RPM Err Time to 1.5 seconds
...b. Proportional Enable RPM Error to 80
...c. Integral Enable RPM Error to 20
...d. Set all your proportional airflow low tables to 0.8 g/sec per 100 RPM from 150 on up.
...e. Set all your integral airflow low tables to 0.2 g/sec per 100 rpm from 100 on up
...f. Set Derivative fast filter to 0.95
...g. Set derivative slow filter to 0.08
...h. Set Derivative rpm low and high tables from 0 through 0.05 to zero. 0.06 to 1.75, 0.08-0.15 to 2.00
6. Engine - Idle - Airflow: Set the following:
...a. Copy your IAC effective area table and paste it 8 cells to the right.
...b. Set your IAC park position airflow to your Base airflow + 33% (times 1.33)
7. After making all these changes, key off, unplug TPS, key on for one minute, key off, plug in TPS, start car and start logging.
Now, if you're interested, here are the WHY's:
I noticed you are very rich on tip out. That is a classic indicator of the min fuel mg set too high. rich idle will cause surging. I verified your injectors are higher flow vs stock. Needs lower min fuel mg. 0.029 is still too high, though lower than stock (0.049)
I noticed when you are coasting down you reach a certain point and your spark suddenly drops 20+ degrees of advance. This is due to the main spark tables still being active when you are idling. I would honestly look at your first two rows of spark timing int he main tables and make sure none are higher than 39 degrees, but I forgot to list it above. Either way, increasing that max speed value allows it to drop into the idle spark tables on coast down.
Your proportional error is too tight, so it's trying to react to natural RPM surge, and the engine responds faster than the IAC. Basically, you need a dead zone where the idle can move around some before any corrective airflow, and then if it gets outside that range, it needs stronger correction.
Needs more proportional support when idle speed dips so it doesn't dip as far.
0 and 400 column idle spark values help provide a natural stall saver.
Your derivative was too active. This will cause the idle to start out stable and then go unstable with time. I saw this a couple of times in your log file.
Your IAC table was still stock, so it was commanding too high an IAC position for the commanded airflow, resulting in the hang followed by surge. Normally on a 92mm I'd go six cells, but since you cracked the screw some, I recommend 8 instead of 6 cells to compensate.
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03-01-2019, 09:56 AM
#8
OK, here is my list of changes for you:
1. Engine - Fuel - Transient: Set min fuel MG to 0.015 and min RPM to 1100
2. Engine - Fuel - DFCO: FOr now, set Enable ETC to 140 C until you get return to idle under control
3. Engine - Spark - idle spark advance (both tables): Set 0 and 400 columns to 32 degrees. Set 800 and 1200 to 18 degrees, set 1600 column to 24 degrees, 2000-4800 to 26
4. Engine - Spark - Advance: Set max speed to 250 mph
5. Engine - Idle - RPM: Set the following:
...a. update RPM Err Time to 1.5 seconds
...b. Proportional Enable RPM Error to 80
...c. Integral Enable RPM Error to 20
...d. Set all your proportional airflow low tables to 0.8 g/sec per 100 RPM from 150 on up.
...e. Set all your integral airflow low tables to 0.2 g/sec per 100 rpm from 100 on up
...f. Set Derivative fast filter to 0.95
...g. Set derivative slow filter to 0.08
...h. Set Derivative rpm low and high tables from 0 through 0.05 to zero. 0.06 to 1.75, 0.08-0.15 to 2.00
6. Engine - Idle - Airflow: Set the following:
...a. Copy your IAC effective area table and paste it 8 cells to the right.
...b. Set your IAC park position airflow to your Base airflow + 33% (times 1.33)
7. After making all these changes, key off, unplug TPS, key on for one minute, key off, plug in TPS, start car and start logging.
Now, if you're interested, here are the WHY's:
I noticed you are very rich on tip out. That is a classic indicator of the min fuel mg set too high. rich idle will cause surging. I verified your injectors are higher flow vs stock. Needs lower min fuel mg. 0.029 is still too high, though lower than stock (0.049)
I noticed when you are coasting down you reach a certain point and your spark suddenly drops 20+ degrees of advance. This is due to the main spark tables still being active when you are idling. I would honestly look at your first two rows of spark timing int he main tables and make sure none are higher than 39 degrees, but I forgot to list it above. Either way, increasing that max speed value allows it to drop into the idle spark tables on coast down.
Your proportional error is too tight, so it's trying to react to natural RPM surge, and the engine responds faster than the IAC. Basically, you need a dead zone where the idle can move around some before any corrective airflow, and then if it gets outside that range, it needs stronger correction.
Needs more proportional support when idle speed dips so it doesn't dip as far.
0 and 400 column idle spark values help provide a natural stall saver.
Your derivative was too active. This will cause the idle to start out stable and then go unstable with time. I saw this a couple of times in your log file.
Your IAC table was still stock, so it was commanding too high an IAC position for the commanded airflow, resulting in the hang followed by surge. Normally on a 92mm I'd go six cells, but since you cracked the screw some, I recommend 8 instead of 6 cells to compensate.
1. Engine - Fuel - Transient: Set min fuel MG to 0.015 and min RPM to 1100
2. Engine - Fuel - DFCO: FOr now, set Enable ETC to 140 C until you get return to idle under control
3. Engine - Spark - idle spark advance (both tables): Set 0 and 400 columns to 32 degrees. Set 800 and 1200 to 18 degrees, set 1600 column to 24 degrees, 2000-4800 to 26
4. Engine - Spark - Advance: Set max speed to 250 mph
5. Engine - Idle - RPM: Set the following:
...a. update RPM Err Time to 1.5 seconds
...b. Proportional Enable RPM Error to 80
...c. Integral Enable RPM Error to 20
...d. Set all your proportional airflow low tables to 0.8 g/sec per 100 RPM from 150 on up.
...e. Set all your integral airflow low tables to 0.2 g/sec per 100 rpm from 100 on up
...f. Set Derivative fast filter to 0.95
...g. Set derivative slow filter to 0.08
...h. Set Derivative rpm low and high tables from 0 through 0.05 to zero. 0.06 to 1.75, 0.08-0.15 to 2.00
6. Engine - Idle - Airflow: Set the following:
...a. Copy your IAC effective area table and paste it 8 cells to the right.
...b. Set your IAC park position airflow to your Base airflow + 33% (times 1.33)
7. After making all these changes, key off, unplug TPS, key on for one minute, key off, plug in TPS, start car and start logging.
Now, if you're interested, here are the WHY's:
I noticed you are very rich on tip out. That is a classic indicator of the min fuel mg set too high. rich idle will cause surging. I verified your injectors are higher flow vs stock. Needs lower min fuel mg. 0.029 is still too high, though lower than stock (0.049)
I noticed when you are coasting down you reach a certain point and your spark suddenly drops 20+ degrees of advance. This is due to the main spark tables still being active when you are idling. I would honestly look at your first two rows of spark timing int he main tables and make sure none are higher than 39 degrees, but I forgot to list it above. Either way, increasing that max speed value allows it to drop into the idle spark tables on coast down.
Your proportional error is too tight, so it's trying to react to natural RPM surge, and the engine responds faster than the IAC. Basically, you need a dead zone where the idle can move around some before any corrective airflow, and then if it gets outside that range, it needs stronger correction.
Needs more proportional support when idle speed dips so it doesn't dip as far.
0 and 400 column idle spark values help provide a natural stall saver.
Your derivative was too active. This will cause the idle to start out stable and then go unstable with time. I saw this a couple of times in your log file.
Your IAC table was still stock, so it was commanding too high an IAC position for the commanded airflow, resulting in the hang followed by surge. Normally on a 92mm I'd go six cells, but since you cracked the screw some, I recommend 8 instead of 6 cells to compensate.
Since Im thinking about it - the build is SS2 cam, Diamond -3cc pistons, 243s shaved .030, 92mm Holley hiRise, fitech 92mmTB, 12613412 injectors, lt4 rods, hastings rings, 10296 oil pump, etc
Last question, did you learn all of this through lots of searching? The Tuning school? Training from other tuners?
The last thing I want to be is spoonfed or that dude that goes on forums and ask for a full tune. I have to know the whys of what Im doing. Im going to take all of your help and make sure I know exactly why Im doing it and what its really affecting before I do it.
Last edited by SmokeyCheese1; 03-01-2019 at 12:44 PM.
03-02-2019, 08:05 AM
#9
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I learned it the hard way. Doing searches helps but you gotta be really careful because there is lots of bad advice out there.
When I did the first couple of builds I had NicD tune it, and I spent a lot of time comparing the tune vs stock. And sidebar -- NicD is the best I know of for tuning. I kept his tune unmolested and tried stuff off the internet, car got worse, went back to the NicD tunes, rinse and repeat. But trial and error learned what did and did not work.
Then, when I did the light clutch and solid roller, I decided to try to conquer it myself, and it was not that difficult. The light clutch was harder than the LLSR was. The real test was when I ditched the maf. First I went to the custom OS SD tune, and got it, but still when I unplugged the maf it went bonkers, and none of the internet knowledge worked on it. It was so responsive the engine would react faster than the IAC could control it.
At that point I gave up the internet stuff and went back to electronics controller knowledge and treated it like I was tuning any other controller PID loop at work. Lots of stuff in the ECU is at its core P, PI, and PID. Especially at idle.
When I did the first couple of builds I had NicD tune it, and I spent a lot of time comparing the tune vs stock. And sidebar -- NicD is the best I know of for tuning. I kept his tune unmolested and tried stuff off the internet, car got worse, went back to the NicD tunes, rinse and repeat. But trial and error learned what did and did not work.
Then, when I did the light clutch and solid roller, I decided to try to conquer it myself, and it was not that difficult. The light clutch was harder than the LLSR was. The real test was when I ditched the maf. First I went to the custom OS SD tune, and got it, but still when I unplugged the maf it went bonkers, and none of the internet knowledge worked on it. It was so responsive the engine would react faster than the IAC could control it.
At that point I gave up the internet stuff and went back to electronics controller knowledge and treated it like I was tuning any other controller PID loop at work. Lots of stuff in the ECU is at its core P, PI, and PID. Especially at idle.
04-05-2019, 05:27 PM
#10
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0 stall saver tables, they will cause more headaches than they're worth trying to fix your issue.
set throttle cracker enable and disable values to 7 and 5 km/h
edit the vacuum areas of main spark tables to help stop rev hang, if its rev hanging on coast there's only so much air you can block off with the IAC motor. if its not enough resolution to yield the results you want use spark as well. a car the holds 1500rpm on coast down with 30 degrees timing will pull back to idle if you only give it 10 degrees. spark can work in conjunction with airflow in order to control dynamic idle
set throttle cracker enable and disable values to 7 and 5 km/h
edit the vacuum areas of main spark tables to help stop rev hang, if its rev hanging on coast there's only so much air you can block off with the IAC motor. if its not enough resolution to yield the results you want use spark as well. a car the holds 1500rpm on coast down with 30 degrees timing will pull back to idle if you only give it 10 degrees. spark can work in conjunction with airflow in order to control dynamic idle