Intermittent high idle
08-21-2015, 11:40 PM
#21
I merged these two threads. I kept thinking I responded when I was reading the other one and was like what the hell happened to my post?
First things first. Get GOOD injector data in there. Everything else you do will be to bandaid that if the injector data is garbage. And it's a problem when it comes to running airflow, cracker/follower, and VE. VE can easily be tuned off the wideband, but the others are not so easy and in the end, you can chase you tail (ask me how I know). I swapped injectors with good, known data, and what took me weeks to fix before took me literally 10 mins to do on a retune.
In fact, most GM tables should be left alone. There's a reason fuel/air/spark are the big three. Get good injector data, clean up the VE table/RAF table, and then adjust spark. That should get you like 95% of the way there. The other tables don't need much adjustment. And if they do, one of the big three is off.
First things first. Get GOOD injector data in there. Everything else you do will be to bandaid that if the injector data is garbage. And it's a problem when it comes to running airflow, cracker/follower, and VE. VE can easily be tuned off the wideband, but the others are not so easy and in the end, you can chase you tail (ask me how I know). I swapped injectors with good, known data, and what took me weeks to fix before took me literally 10 mins to do on a retune.
In fact, most GM tables should be left alone. There's a reason fuel/air/spark are the big three. Get good injector data, clean up the VE table/RAF table, and then adjust spark. That should get you like 95% of the way there. The other tables don't need much adjustment. And if they do, one of the big three is off.
08-22-2015, 12:32 AM
#22
I merged these two threads. I kept thinking I responded when I was reading the other one and was like what the hell happened to my post?
First things first. Get GOOD injector data in there. Everything else you do will be to bandaid that if the injector data is garbage. And it's a problem when it comes to running airflow, cracker/follower, and VE. VE can easily be tuned off the wideband, but the others are not so easy and in the end, you can chase you tail (ask me how I know). I swapped injectors with good, known data, and what took me weeks to fix before took me literally 10 mins to do on a retune.
In fact, most GM tables should be left alone. There's a reason fuel/air/spark are the big three. Get good injector data, clean up the VE table/RAF table, and then adjust spark. That should get you like 95% of the way there. The other tables don't need much adjustment. And if they do, one of the big three is off.
First things first. Get GOOD injector data in there. Everything else you do will be to bandaid that if the injector data is garbage. And it's a problem when it comes to running airflow, cracker/follower, and VE. VE can easily be tuned off the wideband, but the others are not so easy and in the end, you can chase you tail (ask me how I know). I swapped injectors with good, known data, and what took me weeks to fix before took me literally 10 mins to do on a retune.
In fact, most GM tables should be left alone. There's a reason fuel/air/spark are the big three. Get good injector data, clean up the VE table/RAF table, and then adjust spark. That should get you like 95% of the way there. The other tables don't need much adjustment. And if they do, one of the big three is off.
08-22-2015, 03:01 PM
#23
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I merged these two threads. I kept thinking I responded when I was reading the other one and was like what the hell happened to my post?
First things first. Get GOOD injector data in there. Everything else you do will be to bandaid that if the injector data is garbage. And it's a problem when it comes to running airflow, cracker/follower, and VE. VE can easily be tuned off the wideband, but the others are not so easy and in the end, you can chase you tail (ask me how I know). I swapped injectors with good, known data, and what took me weeks to fix before took me literally 10 mins to do on a retune.
In fact, most GM tables should be left alone. There's a reason fuel/air/spark are the big three. Get good injector data, clean up the VE table/RAF table, and then adjust spark. That should get you like 95% of the way there. The other tables don't need much adjustment. And if they do, one of the big three is off.
First things first. Get GOOD injector data in there. Everything else you do will be to bandaid that if the injector data is garbage. And it's a problem when it comes to running airflow, cracker/follower, and VE. VE can easily be tuned off the wideband, but the others are not so easy and in the end, you can chase you tail (ask me how I know). I swapped injectors with good, known data, and what took me weeks to fix before took me literally 10 mins to do on a retune.
In fact, most GM tables should be left alone. There's a reason fuel/air/spark are the big three. Get good injector data, clean up the VE table/RAF table, and then adjust spark. That should get you like 95% of the way there. The other tables don't need much adjustment. And if they do, one of the big three is off.
08-22-2015, 03:49 PM
#24
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I bow to those who can fix intermittent high idle. I wish someone would post a guide on fixing this issue rather than the usual chorus of "your VE tables suck" and "Run the Russ K idle config" and "Check your timing" and "base running airflow warble garble". Well....duh. Given the complexity of HpTuners and the factory PCM it seems to go a little deeper than the usual condescending advice.
As for me and my car, I just gave up and unplugged the IAC. Other than cold start issues (like a carb'd car now..lol) I'm thrilled to have a consistent rock solid idle and driveability with a 236/242 cam.
I became so frustrated browsing forums and trying again and again that I needed a break. I keep telling myself that someday when I get time I'll plug in the IAC and start over...but as for now it's too much fun to drive as is.
As for me and my car, I just gave up and unplugged the IAC. Other than cold start issues (like a carb'd car now..lol) I'm thrilled to have a consistent rock solid idle and driveability with a 236/242 cam.
I became so frustrated browsing forums and trying again and again that I needed a break. I keep telling myself that someday when I get time I'll plug in the IAC and start over...but as for now it's too much fun to drive as is.
08-22-2015, 09:16 PM
#25
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I think Darth_V8r was referring to the "Throttle Cracker" Enable and Disable speeds.
Setting them to e.g. 80 and 81 would get rid of the "cruise control" that some people complain about when slowing down. These values would be similar to disconnecting the IAC. I don't think my 239/251 cam engine would cold start without an IAC.
I actually plan on trying those "80" and "81" values. IMHO the Throttle Cracker's purpose is to prevent the car from slowing dramatically when an everyday driver takes their foot off the throttle, and perhaps increases gas mileage during EPA tests. Millions of people drove millions of carburetored cars without a Throttle Cracker. (Didn't some of the last carburetored cars have something like a throttle cracker for EPA purposes.)
Going back to the original problems, there is a well proven "formula" for tuning the PCM, and going thought the "Russ K idle config" or equivalent is simply part of it. If the Base Idle Airflow is too high/low, the car will not idle correctly, will not return to idle correctly and perhaps even have tip-in problems.
I have changed major parts, intake manifold, injectors, cams, even engines every few months and each time I have to tune everything and I go through all the steps. As the cam's overlap gets higher, some steps become much harder, and IMHO some tables should be disabled because the engine is way outside GM's design specs for the PCM.
Hey, just my novice opinion.
Setting them to e.g. 80 and 81 would get rid of the "cruise control" that some people complain about when slowing down. These values would be similar to disconnecting the IAC. I don't think my 239/251 cam engine would cold start without an IAC.
I actually plan on trying those "80" and "81" values. IMHO the Throttle Cracker's purpose is to prevent the car from slowing dramatically when an everyday driver takes their foot off the throttle, and perhaps increases gas mileage during EPA tests. Millions of people drove millions of carburetored cars without a Throttle Cracker. (Didn't some of the last carburetored cars have something like a throttle cracker for EPA purposes.)
Going back to the original problems, there is a well proven "formula" for tuning the PCM, and going thought the "Russ K idle config" or equivalent is simply part of it. If the Base Idle Airflow is too high/low, the car will not idle correctly, will not return to idle correctly and perhaps even have tip-in problems.
I have changed major parts, intake manifold, injectors, cams, even engines every few months and each time I have to tune everything and I go through all the steps. As the cam's overlap gets higher, some steps become much harder, and IMHO some tables should be disabled because the engine is way outside GM's design specs for the PCM.
Hey, just my novice opinion.
08-23-2015, 02:27 PM
#26
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That's what it was, yes. The numbers were just arbitrarily high enough to get it to stop.
I had the blade cracked a bit too far I think. Tuner re-enabled it but made it less agressive so it'll hold 1100 instead of 1800 while coasting.
Based on how it seems to function, I guess it's there to prevent stalling while braking. Although with it disabled, the idle never stumbled on me.
I had the blade cracked a bit too far I think. Tuner re-enabled it but made it less agressive so it'll hold 1100 instead of 1800 while coasting.
Based on how it seems to function, I guess it's there to prevent stalling while braking. Although with it disabled, the idle never stumbled on me.
08-23-2015, 10:22 PM
#27
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That's what it was, yes. The numbers were just arbitrarily high enough to get it to stop.
I had the blade cracked a bit too far I think. Tuner re-enabled it but made it less agressive so it'll hold 1100 instead of 1800 while coasting.
Based on how it seems to function, I guess it's there to prevent stalling while braking. Although with it disabled, the idle never stumbled on me.
I had the blade cracked a bit too far I think. Tuner re-enabled it but made it less agressive so it'll hold 1100 instead of 1800 while coasting.
Based on how it seems to function, I guess it's there to prevent stalling while braking. Although with it disabled, the idle never stumbled on me.
In short, while I have greatly reduced the "cruise control" problem, I have not yet completely eliminated it.
08-24-2015, 12:43 PM
#28
I'll follow mrvedit advice and see how changing those values helps my car.
Also....aftermarket (such as the Holley EFI on my truck) have tons of background intelligence and make tuning driveability issues a breeze. I'm looking forward to saving up and buying a Holley EFI for my 3rd gen.
08-24-2015, 01:30 PM
#29
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I'd begin by trying to find what makes the "intermittent"
nature. Look at the FTC when it's high and low - are you
maybe seeing an EVAP purge cycle that is sucking on an
open line? Falling into and out of closed loop idle control
due to a flaky temperature sensor? Is your desired air flow
jumping up and the motor following, vs a totally non-
commanded idle RPM setpoint? Does it follow A/C clutch
engage (via the accessory drag torque and a whacked
torque vs air mass model post-cam)? Find the handle.
nature. Look at the FTC when it's high and low - are you
maybe seeing an EVAP purge cycle that is sucking on an
open line? Falling into and out of closed loop idle control
due to a flaky temperature sensor? Is your desired air flow
jumping up and the motor following, vs a totally non-
commanded idle RPM setpoint? Does it follow A/C clutch
engage (via the accessory drag torque and a whacked
torque vs air mass model post-cam)? Find the handle.
08-24-2015, 02:05 PM
#30
Some good stuff here. Although i have no tuning software, it helps a lot to understand whats going on and how many parameters there are. I just never thought I'd be going thru all this w 8 deg of overlap. After dealing with it for 6 months and having to wait for my busy tuner to get an opening, it may push me to buy the software.
08-24-2015, 07:52 PM
#31
I have had good luck turning off follower. well zeroing out the table. and just going off the Cracker for fine tuning under braking. eliminated my hanging idle issues. and the "cruise control" was gone. drops quickly to base idle speed while slowing to a stop. and cleaned up alot of the cam surge i had. 242/252 on 110+4 cam.
08-26-2015, 05:54 PM
#33
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Some good stuff here. Although i have no tuning software, it helps a lot to understand whats going on and how many parameters there are. I just never thought I'd be going thru all this w 8 deg of overlap. After dealing with it for 6 months and having to wait for my busy tuner to get an opening, it may push me to buy the software.
08-26-2015, 06:37 PM
#34
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Update Just picked the car up from the tuner and apparently "the car didn't act up for them". I started the car with them standing there about 4 times and nothing. Drove it home and had zero issues, started it right after and what do you know hello 1500 idle. It comes down in about 5 seconds and will do that a few more times. I'm honestly going to take the car somewhere else to have it figured out. I really do not wanna pay someone 500 for new tune. Maybe I will just tell them the story and say I just need this off idle fixed. Now does anyone know of any places in Illinois that could possibly get this thing figured out for me. I am contemplating unplugging my iac like someone said and leave the car alone for now. I did have one thought but idk if it would have anything to do with it maybe you guys would know better. First off I cleaned out the intake with brake cleaner with the sensor that's in back still in there. Could I have messed that up? Also second thought I did an ls6 Valley cover also did comps trunion upgrade, my passenger side valve cover would not go on with out touching the rockers. So I took both plastic baffles out where the vacuum lines hook up the rear port is now unused, but the front port goes to the top of my throttle body could that be causing my problem?
08-26-2015, 07:49 PM
#35
Can you post your tune and a log of what it's doing at 1500?
This is why it's worth it to invest in the software. Even if you get it professionally tuned, you can log problems and get help a lot faster.
Like I had a MAP problem with my brand new MAP... guess what? The bolts holding the FAST down were coming lose, so unmetered air was leaking in causing the MAP to read weird. I found that with HPTuners.
This is why it's worth it to invest in the software. Even if you get it professionally tuned, you can log problems and get help a lot faster.
Like I had a MAP problem with my brand new MAP... guess what? The bolts holding the FAST down were coming lose, so unmetered air was leaking in causing the MAP to read weird. I found that with HPTuners.
08-26-2015, 08:17 PM
#36
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I torqued my LSXR to 80 in/lbs and left it overnight. Next day, it took another half turn to reach 80 in/lbs again.
Jake: do you have your MAP at the front or back of the LSXR?
As JakeFusion says, having HP Tuners, EFI Live or at least a good scanner is essential for debugging some of these problems.
I wonder if your PCM is not always reading the closed throttle at 0%. This could cause the Throttle Cracker to kick in and raise your RPMs. Straight forward to check when it happens with the right tools. Not even a good tuner can always fix an intermittent problem.
Jake: do you have your MAP at the front or back of the LSXR?
As JakeFusion says, having HP Tuners, EFI Live or at least a good scanner is essential for debugging some of these problems.
I wonder if your PCM is not always reading the closed throttle at 0%. This could cause the Throttle Cracker to kick in and raise your RPMs. Straight forward to check when it happens with the right tools. Not even a good tuner can always fix an intermittent problem.
08-27-2015, 07:03 AM
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Can you post your tune and a log of what it's doing at 1500?
This is why it's worth it to invest in the software. Even if you get it professionally tuned, you can log problems and get help a lot faster.
Like I had a MAP problem with my brand new MAP... guess what? The bolts holding the FAST down were coming lose, so unmetered air was leaking in causing the MAP to read weird. I found that with HPTuners.
This is why it's worth it to invest in the software. Even if you get it professionally tuned, you can log problems and get help a lot faster.
Like I had a MAP problem with my brand new MAP... guess what? The bolts holding the FAST down were coming lose, so unmetered air was leaking in causing the MAP to read weird. I found that with HPTuners.
Heres all i have on the dyno sheet. I talked to another guy last night thats good with ls cars. Im going to drop it off to him next week. What kind of software should i look at amd buy. Now that the car isnt stock like you said it be very helpful to have