Question about Idle Speed Maps

[Mscromer]

This weekend I’m going to really work on getting my rebuilt 944 turbo engine to idle better by using TunerPro and the Osterich. I’ve checked for vacuum leaks and found none. Also replaced the DME temp sensors with a new Bosch one. I also have a little bit bigger cam 480 lift 233 duration nothing crazy should still be very street drivable. From everything I’ve read on Toms in-depth tuner write up I need to adjust the idle timing. Once im driving the engine runs perfect. I’m sure it could be tweaked to get a little more horse power but right now I just want it to idle better. It does idle better once warm but it can still use some adjustments. My main question about the idle speed map is I have a F9T DME and I read in Toms write up that pin 28 from the DME needs to be grounded for the idle speed maps to work? The wire from pin 28 is going to the altitude switch I believe, so do I just unplug the altitude switch and run the wire from pin 28 to ground? Any additional info I might be able to use to make this car idle better would be greatly appreciated.

[walfreyydo]

Timing is important but what is more important is your AFR's at idle. I assume you have a wideband O2 and its correctly hooked up to MS and reading within Tuner Studio.

First thing when tuning idle is to tune it when the engine is fully warmed up. That means a coolant temp above approximately 170F. Assuming you have a startup tune that runs good enough to get it started and idling long enough to do so. Youll need to configure fuel, air and timing.

For Open Loop Idle (closed loop can be done later once you get these in the ballpark)

Fuel
Once warmed up, youll want to configure your fueling. Focus on the range of cells in the lower left (make sure you have your binning correct as well, mine is set for an NA car but youll want similar RPM break points but your kpa should go up to 150 to 200 depending on your max boost). Blocks in the range of below 40kpa and below 1500 RPM. Set your VE values to where the AFRs read within the 12-13.5 range (you can tweak this later). Too lean and the car will surge (hence why a vacuum leak causes surging), so richen it up a bit if you are getting surging.

Air/Idle RPM:
The idle speed RPM is set by the ICV setting (and for cars equipped with it, the idle screw, which the 16V cars do not have). You set the idle air control valve under the PWM Idle Duty Cycle interface. Concentrate on the settings in the warm temp areas for now and set your % so the car idles at the correct RPM range. Once its in the ballpark for the desired idle RPM, then go back to your fuel table and adjust your VE values to balance them out so it idles at the desired RPM and within the correct AFR range.

Timing:
With timing youll want to configure it to get max vacuum at idle RPM. 10 degrees is a good starting point. Youll want to build a "valley" in your timing table, with timing being higher above/below your desired RPM. This is to help stabilize idle so if it drops too low, additional timing is added to help it correct (Alternatively, this can also be configured in the idle advance timing settings instead of directly in your timing table). Here is an example of my timing table (note: this is a 16V S2 at 93 octane, so not advised to use these same values beyond the idle range for your application):



Once you get open loop warm idle configured, then you can let the car cool down and start playing around with the cold idle, most importantly the warmup enrichment, as well as the idle PWM Idle Duty Cycle for the other temp ranges. From there you can move on to closed loop idle (which is basically dynamic idle correction, which is better than open loop but not 100% required). Always start idle tuning with the car warm, because warm up enrichment is just a fuel adder over the warm idle fuel settings, so that needs to be configured first.

Lastly here is the DIYAutotune guide (there are many other guides on their how to guides section):
https://diyautotune.com/blogs/how-to-gu ... nXu_yhZKaO

I would also recommend the videos on youtube, in particular "Turbine Research" channel which has some great basic guides on tuning your car beyond just idle tuning.

[Mscromer]

Timing is important but what is more important is your AFR's at idle. I assume you have a wideband O2 and its correctly hooked up to MS and reading within Tuner Studio.

First thing when tuning idle is to tune it when the engine is fully warmed up. That means a coolant temp above approximately 170F. Assuming you have a startup tune that runs good enough to get it started and idling long enough to do so. Youll need to configure fuel, air and timing.

For Open Loop Idle (closed loop can be done later once you get these in the ballpark)

Fuel
Once warmed up, youll want to configure your fueling. Focus on the range of cells in the lower left (make sure you have your binning correct as well, mine is set for an NA car but youll want similar RPM break points but your kpa should go up to 150 to 200 depending on your max boost). Blocks in the range of below 40kpa and below 1500 RPM. Set your VE values to where the AFRs read within the 12-13.5 range (you can tweak this later). Too lean and the car will surge (hence why a vacuum leak causes surging), so richen it up a bit if you are getting surging.

Air/Idle RPM:
The idle speed RPM is set by the ICV setting (and for cars equipped with it, the idle screw, which the 16V cars do not have). You set the idle air control valve under the PWM Idle Duty Cycle interface. Concentrate on the settings in the warm temp areas for now and set your % so the car idles at the correct RPM range. Once its in the ballpark for the desired idle RPM, then go back to your fuel table and adjust your VE values to balance them out so it idles at the desired RPM and within the correct AFR range.

Timing:
With timing youll want to configure it to get max vacuum at idle RPM. 10 degrees is a good starting point. Youll want to build a "valley" in your timing table, with timing being higher above/below your desired RPM. This is to help stabilize idle so if it drops too low, additional timing is added to help it correct (Alternatively, this can also be configured in the idle advance timing settings instead of directly in your timing table). Here is an example of my timing table (note: this is a 16V S2 at 93 octane, so not advised to use these same values beyond the idle range for your application):



Once you get open loop warm idle configured, then you can let the car cool down and start playing around with the cold idle, most importantly the warmup enrichment, as well as the idle PWM Idle Duty Cycle for the other temp ranges. From there you can move on to closed loop idle (which is basically dynamic idle correction, which is better than open loop but not 100% required). Always start idle tuning with the car warm, because warm up enrichment is just a fuel adder over the warm idle fuel settings, so that needs to be configured first.

Lastly here is the DIYAutotune guide (there are many other guides on their how to guides section):
https://diyautotune.com/blogs/how-to-gu ... nXu_yhZKaO

I would also recommend the videos on youtube, in particular "Turbine Research" channel which has some great basic guides on tuning your car beyond just idle tuning.

Thank you so much for this. I will follow this this weekend and see what happens. I do have a WBO2 and right now at idle it sits right at 14.7. I’m using TurnerPro to make all the adjustments to the DME. I’ve never messed with Tuner Studio. Will I be able to make all the DME adjustment like in TunerPro or is Tuner Studio something different.

Edit: bear with me on this I’m learning all this tuning stuff.

[walfreyydo]

I totally misread TunerPro vs Tuner Studio! My bad. Tuner Studio is only really used for Megasquirt or Speeduino platforms (maybe others). If you are burning a chip and installing that chip in the factory DME computer then TunerPro is what youll have to use.

TunerPro I have used a little bit but its a totally different setup/user interface than Tuner Studio so alot of what I wrote wont apply directly (the principals do indirectly though). I recall that for fuel maps on the 944 there were three different ones - idle, part throttle and WOT (dependent on reading from the TPS), but I think it was similar on the turbo as well (despite having a variable TPS). Timing I think is one singular map and contains an x and y axis whereas the fuel tables are only an X axis (RPM) and a fuel value hardcoded to one of the three throttle states, IIRC.

If you are interested, Rogue Tuning still hosts files for the 944s that can be brought into TunerPro that you could use to reverse engineer and tweak your setup (this is what I did when I was looking for some baseline ignition timing numbers which I then configured in Tuner Studio) but there may be other settings you could identify in those files as well:
https://www.roguetuning.com/diy_free_944_tuning_tools

Just make sure you take those tunes with a grain of salt and make sure you verify your AFR and especially timing values, and dont blindly trust whats in those Rogue files, just to be safe as all cars (even stock) are different and one tune on one particular car shouldnt be trusted to work on someone elses car.

Overall, the principals are still likely the same, but using different software and the bosch motronic platform may mean its configured in a different location or in a different way. Im sure there are others on these forums that have more direct experience with TunerPro to help advise you on the specific settings and where they are found. Seems like theres also a good selection of Youtube videos such as this one.

[Tom]

I totally misread TunerPro vs Tuner Studio! My bad. Tuner Studio is only really used for Megasquirt or Speeduino platforms (maybe others). If you are burning a chip and installing that chip in the factory DME computer then TunerPro is what youll have to use.

TunerPro I have used a little bit but its a totally different setup/user interface than Tuner Studio so alot of what I wrote wont apply directly (the principals do indirectly though). I recall that for fuel maps on the 944 there were three different ones - idle, part throttle and WOT (dependent on reading from the TPS), but I think it was similar on the turbo as well (despite having a variable TPS). Timing I think is one singular map and contains an x and y axis whereas the fuel tables are only an X axis (RPM) and a fuel value hardcoded to one of the three throttle states, IIRC.

If you are interested, Rogue Tuning still hosts files for the 944s that can be brought into TunerPro that you could use to reverse engineer and tweak your setup (this is what I did when I was looking for some baseline ignition timing numbers which I then configured in Tuner Studio) but there may be other settings you could identify in those files as well:
https://www.roguetuning.com/diy_free_944_tuning_tools

Just make sure you take those tunes with a grain of salt and make sure you verify your AFR and especially timing values, and dont blindly trust whats in those Rogue files, just to be safe as all cars (even stock) are different and one tune on one particular car shouldnt be trusted to work on someone elses car.

Overall, the principals are still likely the same, but using different software and the bosch motronic platform may mean its configured in a different location or in a different way. Im sure there are others on these forums that have more direct experience with TunerPro to help advise you on the specific settings and where they are found.

In case you missed it, we put a ton of effort into advancing the art of 944 turbo chip tuning/burning -- opening up virtually all DME maps, many of which were inaccessible previously; fixing some maps that didn't work right in the Rogue materials (such as idle speed coincidentally); making other maps more understandable, etc. I'm biased of course, but believe we have (by far) the most complete chip tuning guide and files available on the internet right here on Carpokes:

https://www.carpokes.com/viewtopic.php?t=4391#p49497

Edit: this is for people who want to burn chips for the original DME or F9 DME, of course, not for stand-alone systems...

[Tom]

This weekend I’m going to really work on getting my rebuilt 944 turbo engine to idle better by using TunerPro and the Osterich. I’ve checked for vacuum leaks and found none. Also replaced the DME temp sensors with a new Bosch one. I also have a little bit bigger cam 480 lift 233 duration nothing crazy should still be very street drivable. From everything I’ve read on Toms in-depth tuner write up I need to adjust the idle timing. Once im driving the engine runs perfect. I’m sure it could be tweaked to get a little more horse power but right now I just want it to idle better. It does idle better once warm but it can still use some adjustments. My main question about the idle speed map is I have a F9T DME and I read in Toms write up that pin 28 from the DME needs to be grounded for the idle speed maps to work? The wire from pin 28 is going to the altitude switch I believe, so do I just unplug the altitude switch and run the wire from pin 28 to ground? Any additional info I might be able to use to make this car idle better would be greatly appreciated.

I'm not sure I'd focus on timing as the primary tool for your idle quality. The DME uses timing to make quick micro-changes to idle speed, you so are fighting against that a bit. Similarly, the closed loop O2 system will fight you on tuning the AFR for better idle quality. You can experiment and see if improvements can be had that way, but if the cam is the issue, your best bet is probably just to raise the idle rpm target to a bit. As for the idle speed maps, there are a several, and we have them all exposed in the Carpokes XDF, so however your F9 is configured, one of the idle speed maps should work. It's best to use the primary map, however, as the A/C idle speed does not work in the alternate maps. I'll post details on that for your F9 when I have more time this afternoon...

[Mscromer]

This weekend I’m going to really work on getting my rebuilt 944 turbo engine to idle better by using TunerPro and the Osterich. I’ve checked for vacuum leaks and found none. Also replaced the DME temp sensors with a new Bosch one. I also have a little bit bigger cam 480 lift 233 duration nothing crazy should still be very street drivable. From everything I’ve read on Toms in-depth tuner write up I need to adjust the idle timing. Once im driving the engine runs perfect. I’m sure it could be tweaked to get a little more horse power but right now I just want it to idle better. It does idle better once warm but it can still use some adjustments. My main question about the idle speed map is I have a F9T DME and I read in Toms write up that pin 28 from the DME needs to be grounded for the idle speed maps to work? The wire from pin 28 is going to the altitude switch I believe, so do I just unplug the altitude switch and run the wire from pin 28 to ground? Any additional info I might be able to use to make this car idle better would be greatly appreciated.

I'm not sure I'd focus on timing as the primary tool for your idle quality. The DME uses timing to make quick micro-changes to idle speed, you so are fighting against that a bit. Similarly, the closed loop O2 system will fight you on tuning the AFR for better idle quality. You can experiment and see if improvements can be had that way, but if the cam is the issue, your best bet is probably just to raise the idle rpm target to a bit. As for the idle speed maps, there are a several, and we have them all exposed in the Carpokes XDF, so however your F9 is configured, one of the idle speed maps should work. It's best to use the primary map, however, as the A/C idle speed does not work in the alternate maps. I'll post details on that for your F9 when I have more time this afternoon...

Thank you Tom. I’m using all the tunes and xdf files from carpokes. I’m trying to figure all this out my self from reading your entire tuning guide several times along with searching else were online. I’m also using ChatGPT but I of course don’t trust ChatGPT 100%. It tells me to adjust timing first due to the cam. It says bigger cams like more timing. I’d rather trust your real live experiences with the 944. So at this point I’ve searched and read so much with everything saying something different I’m more confused now than when I started. Lol. Like I’ve said before it runs great while driving it just idles rough. I know I have a bigger cam but it’s not that much bigger. I would think it would still be able to have a smooth calm idle. I’ve reached out to people mention here on carpokes by email to pay for help with the tune but haven’t heard back from them. Again thanks for all your help!

[Tom]

The F9 DMEs that have a built-in MAP sensor connector have a quirk that can force them onto the wrong idle-speed map if you do not have a MAP sensor installed. I’m not sure if that applies to your setup, but if it does, it may be contributing to your current idle issue.

The issue is that it can reduce the idle target slightly, from the normal 840 rpm target down to 800 rpm, and it also defeats the A/C idle-speed increase. With any performance cam, a little more idle speed usually helps smooth things out, while lower idle speed makes the engine less stable. So if your idle is already lower than normal, it will not idle as nicely as stock --and adding a performance cam makes that worse. I’d be inclined to raise the idle in 40 rpm increments --880, 920, 960, etc. -- until you are happy with the idle quality.

You are right that Pin 28 needs to be grounded for the idle-speed circuit to work correctly. However — and this is the big quirk — even if the harness wire at Pin 28 is connected to ground, that wire is not connected inside the F9 DME as needed for the code to select the right idle map.

F9 followed the configuration originally created by Vitesse Racing, and later used by Rogue, where the Pin 28 signal was repurposed as a MAP input. Vitesse and Rogue had you cut the harness wire at Pin 28 and connect the MAP sensor to it. F9 wanted to avoid requiring people to cut wires, so they made that change on the circuit board instead.

The only problem is that if you do not install a MAP sensor, that input floats and is not grounded. So even if you ground the harness wire at Pin 28, that ground signal never reaches the ADC circuit inside the DME that needs to see ground for the idle-speed maps to work correctly.

Until we discovered the issue here on Carpokes, no one (including F9) was aware that cutting that signal without installing a MAP sensor would alter which idle speed cells were used by the DME. Prior to the F9 DME, the issue never came up because the only people cutting the pin 28 wire were doing it in order to install a MAP sensor. The F9 DME introduced the scenario where pin 28 is 'cut' (on the circuit board) even if no MAP sensor is installed.

Fortunately, it is easy to tell if you have this issue, and easy to correct if you do.

To test it, connect the Ostrich and open TunerPro RT using the Carpokes XDF. You will see three idle-speed maps you can adjust. The main idle-speed map has only three cells, which should be set to 840 on a stock map. Once the car is warmed up, try changing all three cells to 1000 and see if the idle speed increases.

If the idle speed goes up, your DME does not have the Pin 28 quirk, and all is good.

If nothing happens, try the “alternate” idle-speed map. That one has four cells, and on a stock chip they should all be set to 800. Change all four of those cells to 1000 and see if the idle speed goes up. If so, that means you need to deal with the Pin 28 ground quirk. To do that, plug the pigtail that comes with the DME into the MAP sensor connector and short the signal wire to the ground wire (and cap off the power wire so it can't accidentally touch anything). That has the same effect as grounding Pin 28 on a standard DME, and should allow the DME to use the normal three-cell idle-speed map.

You want to use the normal three-cell map if possible, not the alternate map, because the alternate map does not let you change the A/C idle speed.

See this post, and the surrounding discussion on idle speed, for more background:

https://carpokes.com/viewtopic.php?t=3574&start=130#p49326

Hope that helps. It was a real pilgrimage to uncover all that info, with thanks to people like johnb, Dave W, and Whalenlg, and you won't find it anywhere else on the Internet unless/until our little Carpokes discovery starts making the rounds elsewhere...

[Mscromer]

The F9 DMEs that have a built-in MAP sensor connector have a quirk that can force them onto the wrong idle-speed map if you do not have a MAP sensor installed. I’m not sure if that applies to your setup, but if it does, it may be contributing to your current idle issue.

The issue is that it can reduce the idle target slightly, from the normal 840 rpm target down to 800 rpm, and it also defeats the A/C idle-speed increase. With any performance cam, a little more idle speed usually helps smooth things out, while lower idle speed makes the engine less stable. So if your idle is already lower than normal, it will not idle as nicely as stock --and adding a performance cam makes that worse. I’d be inclined to raise the idle in 40 rpm increments --880, 920, 960, etc. -- until you are happy with the idle quality.

You are right that Pin 28 needs to be grounded for the idle-speed circuit to work correctly. However — and this is the big quirk — even if the harness wire at Pin 28 is connected to ground, that wire is not connected inside the F9 DME as needed for the code to select the right idle map.

F9 followed the configuration originally created by Vitesse Racing, and later used by Rogue, where the Pin 28 signal was repurposed as a MAP input. Vitesse and Rogue had you cut the harness wire at Pin 28 and connect the MAP sensor to it. F9 wanted to avoid requiring people to cut wires, so they made that change on the circuit board instead.

The only problem is that if you do not install a MAP sensor, that input floats and is not grounded. So even if you ground the harness wire at Pin 28, that ground signal never reaches the ADC circuit inside the DME that needs to see ground for the idle-speed maps to work correctly.

Until we discovered the issue here on Carpokes, no one (including F9) was aware that cutting that signal without installing a MAP sensor would alter which idle speed cells were used by the DME. Prior to the F9 DME, the issue never came up because the only people cutting the pin 28 wire were doing it in order to install a MAP sensor. The F9 DME introduced the scenario where pin 28 is 'cut' (on the circuit board) even if no MAP sensor is installed.

Fortunately, it is easy to tell if you have this issue, and easy to correct if you do.

To test it, connect the Ostrich and open TunerPro RT using the Carpokes XDF. You will see three idle-speed maps you can adjust. The main idle-speed map has only three cells, which should be set to 840 on a stock map. Once the car is warmed up, try changing all three cells to 1000 and see if the idle speed increases.

If the idle speed goes up, your DME does not have the Pin 28 quirk, and all is good.

If nothing happens, try the “alternate” idle-speed map. That one has four cells, and on a stock chip they should all be set to 800. Change all four of those cells to 1000 and see if the idle speed goes up. If so, that means you need to deal with the Pin 28 ground quirk. To do that, plug the pigtail that comes with the DME into the MAP sensor connector and short the signal wire to the ground wire (and cap off the power wire so it can't accidentally touch anything). That has the same effect as grounding Pin 28 on a standard DME, and should allow the DME to use the normal three-cell idle-speed map.

You want to use the normal three-cell map if possible, not the alternate map, because the alternate map does not let you change the A/C idle speed.

See this post, and the surrounding discussion on idle speed, for more background:

https://carpokes.com/viewtopic.php?t=3574&start=130#p49326

Hope that helps. It was a real pilgrimage to uncover all that info, with thanks to people like johnb, Dave W, and Whalenlg, and you won't find it anywhere else on the Internet unless/until our little Carpokes discovery starts making the rounds elsewhere...

I can’t thank you, Johnb, Dave W and Whalenlg enough for helping everyone with these cars. Carpokes is the best Porsche forum out there. Thank you!

[Tom]

The F9 DMEs that have a built-in MAP sensor connector have a quirk that can force them onto the wrong idle-speed map if you do not have a MAP sensor installed. I’m not sure if that applies to your setup, but if it does, it may be contributing to your current idle issue.

The issue is that it can reduce the idle target slightly, from the normal 840 rpm target down to 800 rpm, and it also defeats the A/C idle-speed increase. With any performance cam, a little more idle speed usually helps smooth things out, while lower idle speed makes the engine less stable. So if your idle is already lower than normal, it will not idle as nicely as stock --and adding a performance cam makes that worse. I’d be inclined to raise the idle in 40 rpm increments --880, 920, 960, etc. -- until you are happy with the idle quality.

You are right that Pin 28 needs to be grounded for the idle-speed circuit to work correctly. However — and this is the big quirk — even if the harness wire at Pin 28 is connected to ground, that wire is not connected inside the F9 DME as needed for the code to select the right idle map.

F9 followed the configuration originally created by Vitesse Racing, and later used by Rogue, where the Pin 28 signal was repurposed as a MAP input. Vitesse and Rogue had you cut the harness wire at Pin 28 and connect the MAP sensor to it. F9 wanted to avoid requiring people to cut wires, so they made that change on the circuit board instead.

The only problem is that if you do not install a MAP sensor, that input floats and is not grounded. So even if you ground the harness wire at Pin 28, that ground signal never reaches the ADC circuit inside the DME that needs to see ground for the idle-speed maps to work correctly.

Until we discovered the issue here on Carpokes, no one (including F9) was aware that cutting that signal without installing a MAP sensor would alter which idle speed cells were used by the DME. Prior to the F9 DME, the issue never came up because the only people cutting the pin 28 wire were doing it in order to install a MAP sensor. The F9 DME introduced the scenario where pin 28 is 'cut' (on the circuit board) even if no MAP sensor is installed.

Fortunately, it is easy to tell if you have this issue, and easy to correct if you do.

To test it, connect the Ostrich and open TunerPro RT using the Carpokes XDF. You will see three idle-speed maps you can adjust. The main idle-speed map has only three cells, which should be set to 840 on a stock map. Once the car is warmed up, try changing all three cells to 1000 and see if the idle speed increases.

If the idle speed goes up, your DME does not have the Pin 28 quirk, and all is good.

If nothing happens, try the “alternate” idle-speed map. That one has four cells, and on a stock chip they should all be set to 800. Change all four of those cells to 1000 and see if the idle speed goes up. If so, that means you need to deal with the Pin 28 ground quirk. To do that, plug the pigtail that comes with the DME into the MAP sensor connector and short the signal wire to the ground wire (and cap off the power wire so it can't accidentally touch anything). That has the same effect as grounding Pin 28 on a standard DME, and should allow the DME to use the normal three-cell idle-speed map.

You want to use the normal three-cell map if possible, not the alternate map, because the alternate map does not let you change the A/C idle speed.

See this post, and the surrounding discussion on idle speed, for more background:

https://carpokes.com/viewtopic.php?t=3574&start=130#p49326

Hope that helps. It was a real pilgrimage to uncover all that info, with thanks to people like johnb, Dave W, and Whalenlg, and you won't find it anywhere else on the Internet unless/until our little Carpokes discovery starts making the rounds elsewhere...

I can’t thank you, Johnb, Dave W and Whalenlg enough for helping everyone with these cars. Carpokes is the best Porsche forum out there. Thank you!

Thank you for saying that. Sincerely appreciate it. I like to say we have the highest signal-to-noise ratio in the business. You'll get 20 answers within an hour on Facebook, but you won't get this.

p.s., you do have an F9 DME with MAP connector and no MAF sensor?