Idle Speed Not Automatically Changing

[LaTechGTO]

I am not sure how long this has been occurring, but I didn't notice it until after I started running my 3 Bar tune and trying to make adjustments to the idle airflow. I plan on testing a 2 bar tune tomorrow to test and see if it's just a 3 bar quirk.

The desired idle speed doesn't change as the ECT increases as prescribed in the tune. If you also notice in the log, once I move the gear selector from P to R, the desired idle then changes to where it is supposed to be. When I move the selector from R, the desired idle speed updates again. For some reason the desired idle speed only updates when a gears change occurs.

Any ideas?

IDLE-Airflow.cfg
New Tune Old Version 28 Tire 5 Idle.hpt
Idle RPM Example.hpl

[LaTechGTO]

Bump! Please help

[Lakegoat]

My observation is you have timing jumping from 19 to 36 degrees at idle---isn't that a lot? Mine is around 15 to 16 and stays in a pretty small range.
I guess that depends on your cam setup.
I had some weird idle issues (SD tuned) and I zeroed out my maf table and it went away. MAF was failed correctly and still had some effect ????
Is your MAP sensor linear and offset correct?

[LaTechGTO]

My observation is you have timing jumping from 19 to 36 degrees at idle---isn't that a lot? Mine is around 15 to 16 and stays in a pretty small range.
I guess that depends on your cam setup.
I had some weird idle issues (SD tuned) and I zeroed out my maf table and it went away. MAF was failed correctly and still had some effect ????
Is your MAP sensor linear and offset correct?

Yeah, it is pretty typical for my cam setup .242/.253 .650/.650 112+3 (IIRC). All of my recent setups like to idle in the mid/low 20s, especially since I "loosened" up the over/underspeed correction.

Hmmmm... that is interesting... I haven't had any SD related issues with this car since 2010 or so. I have the "MAF Frequency Fail High" set to "0".

Yes, I believe the MAP information is correct; DPE 2.5 bar sensor - Linear 244.69 kPa & Offset 10.21 kPa.

Thanks for the input, but I just can't seem to figure out why the idle won't transition as it should as ECT raises.

[Lakegoat]

I had my maf fail set to 0 also. I don't know if this has anything to do with this, but your PE was set at 19% throttle, hot and cold and 0 delay. Mine is set at 50% throttle, 1200 rpm delay. My car idles at above 19% throttle. Don't know if this helps, I just had some of the same funny idle problems. Sometimes I would have to start it and turn it off 4 times to get the idle to come down. Changed the maf tables to 0 and no more problems. Can't explain it. Hope you find it. Maybe the temperature sensor in the head?

[LaTechGTO]

I had my maf fail set to 0 also. I don't know if this has anything to do with this, but your PE was set at 19% throttle, hot and cold and 0 delay. Mine is set at 50% throttle, 1200 rpm delay. My car idles at above 19% throttle. Don't know if this helps, I just had some of the same funny idle problems. Sometimes I would have to start it and turn it off 4 times to get the idle to come down. Changed the maf tables to 0 and no more problems. Can't explain it. Hope you find it. Maybe the temperature sensor in the head?

That's odd... It's showing correctly in mine.

PE shouldn't affect the issueI'm having now because my fueling and all of the idle characteristics are fine. The car start great and comes to idle pretty good. Perfect? Naaaaah, but it always starts on the first crank. It does need some adjusting because sometimes it will stumble around some on a cold start as the temps outside change.

What I'm experiencing is that as the engine warms up, the Desired Idle RPM doesn't adjust as I have it set in the tune... Until I move the shift selector. For some reason I didn't start noticing this happening until I went to a 3bar tune.

[LaTechGTO]

Bump!

[LaTechGTO]

Here is a log file using the same configuration as earlier. All that has changed is that I turned the PRNDL on and smoothed out some of my VE table. Still a 3 bar OS.

The car thinks it in D4 because something funky is going on with my tune/P-N-P switch.... Buuuut you can see that the desired idle speed adjusts as it is supposed to while the car warms up.

Idle RPM Example PRNDL.hpl

New Tune Old Version 28 Tire 6 Adjusted VE.hpt

PS - this isn't my normal tune file naming convention

[LaTechGTO]

Can anyone please help? I am just baffled as to why the PCM will adjust the idle RPM automatically as the ECT raises (like it's meant to) when PRNDL is enabled, and the idle adjustment won't occur when PRNDL is set to "None".

[LaTechGTO]

Any ideas?

[LaTechGTO]

Bueller? I have also PMd a few of the HPT guys with no response in return... not sure what to do.

[LaTechGTO]

3 years later, and I am still trying to figure out why this is happening... any help? Also, after failed start, the Desired Idle RPM drops to 0 then counts up to the correct number based on gear position and ECT.

V2.14 Fueling.hpt
Desired Idle RPM Not Changing.hpl
Idle Desired Reset.hpl
GTO WOT.Layout.xml

[LaTechGTO]

Bump for some help, please!

[LaTechGTO]

Forgot to provide closure to anyone that might be having this same issue. When I did the segment swap, I never segment swapped the engine and engine diagnostic segments from an auto file. Once this was done, all of the idle ghosts disappeared, and the computer started referencing the correct tables. Finally fixed this about 8 months ago lol.

Now everything seems to be working... except the fuel level gauge. Could be completely unrelated to the tune, but I did some troubleshooting tonight and made me think about these threads where I was chasing gremlins.

Originally a manual GTO and now has a properly functioning 4L80E and flex fuel sensor. Once I added an input shaft speed sensor, the "calculated gear ratio" started working so now I can calculate slip through the TC and through the clutches separately and easily.

[mbray01]

The fuel level sensor is known to have issues, pretty simple to get to and check, usually corrosion on board, or the contacts loose tension. As far as the segment swap stuff, yes thats tough to figure out, but when doing manual to auto swaps, there is tons of background stuff thats missing in manual files. It becomes really imperative if vehicles with keyless starter setups(vettes)

[LaTechGTO]

The fuel level sensor is known to have issues, pretty simple to get to and check, usually corrosion on board, or the contacts loose tension. As far as the segment swap stuff, yes thats tough to figure out, but when doing manual to auto swaps, there is tons of background stuff thats missing in manual files. It becomes really imperative if vehicles with keyless starter setups(vettes)

Thanks for the tips! Maybe I am missing something simple here too.

I've checked the board on the fuel bucket numerous times to ensure everything was contacting properly and clean. I unplugged the harness then spent a few hours with a multimeter and resistors last night, applying the resistance between the wires as prescribed in the troubleshooting section of the factory manuals (40-250 ohms). There were some really funky things going on, and I even went back to write a few files where I knew the fuel gauge was operating correctly. The fuel level gauge in the dash and the fuel level displayed in the scanner doesn't seem to always match. More troubleshooting over the next few days...

[anniversaryss]

Thank you so much for this insight. I've had a 4l80e in my fbody for years now and my idle desired never moves with the ECT value change unless i put it in gear and back to park.

So you did the segment swap for the transmission and transmission diag but never segment swapped the engine and engine diagnostics from the auto tune? And when you did it worked fine?

If you are still around and can provide insight that would be great!

[LaTechGTO]

Thanks for the tips! Maybe I am missing something simple here too.

I've checked the board on the fuel bucket numerous times to ensure everything was contacting properly and clean. I unplugged the harness then spent a few hours with a multimeter and resistors last night, applying the resistance between the wires as prescribed in the troubleshooting section of the factory manuals (40-250 ohms). There were some really funky things going on, and I even went back to write a few files where I knew the fuel gauge was operating correctly. The fuel level gauge in the dash and the fuel level displayed in the scanner doesn't seem to always match. More troubleshooting over the next few days...

Turned out the fuel level sensor was due to a sticking float. When I changed the fuel bucket and went to twin 450s, the bucket turned ever so slightly where the float was hanging up on the tank's internal baffle.

Thank you so much for this insight. I've had a 4l80e in my fbody for years now and my idle desired never moves with the ECT value change unless i put it in gear and back to park.

So you did the segment swap for the transmission and transmission diag but never segment swapped the engine and engine diagnostics from the auto tune? And when you did it worked fine?

If you are still around and can provide insight that would be great!

In the process of going to an auto tune file, I loaded the transmission/transmission diagnostic from a 2004 express van, but I didn't load the engine/engine diagnostic segment from an auto GTO model and just used the engine/engine diagnostic from my original manual file, not realizing it would make a difference (only had a clue when I saw the segment numbers were different between the two).

Once I loaded the engine diagnostic segment from an auto file, the commanded idle setting began working. Might have loaded the engine segment from an auto file as well, but I don't recall.

[anniversaryss]

Turned out the fuel level sensor was due to a sticking float. When I changed the fuel bucket and went to twin 450s, the bucket turned ever so slightly where the float was hanging up on the tank's internal baffle.



In the process of going to an auto tune file, I loaded the transmission/transmission diagnostic from a 2004 express van, but I didn't load the engine/engine diagnostic segment from an auto GTO model and just used the engine/engine diagnostic from my original manual file, not realizing it would make a difference (only had a clue when I saw the segment numbers were different between the two).

Once I loaded the engine diagnostic segment from an auto file, the commanded idle setting began working. Might have loaded the engine segment from an auto file as well, but I don't recall.

Alright thank you. I have the 80e trans segment (not sure where it came from honestly) but I used the expressvan trans diag just in case.

Now I went into an fbody auto pcm and swapped the engine and engine diag segment. I had to move everything over from my current tune and as soon as I can (weather permitting ) I will load this up and get back to this thread.

I really hope it works. It's been an annoyance that I've lived with but would be great to fix.

Thank you again.

[anniversaryss]

It actually make sense bc the manuals dont technically have a "park". And it makes sense there is somthing in the background that hpt doesnt let you modify or its just somthing that is undefined between the auto/manual files.