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Discussion Starter #1
Ok I have noticed this on every single vid I see and hear and also have this same issue. I build v twin scoots with tons of hp so this irritates me. The forever time it takes for these engines to come back down to idle. This to me is an issue with not enough fuel at the zero poison in the fuel mapping. This in my opinion is for emissions. So when I get to the point of getting an unlocked ecu and start the tuneing process we will see what we can do about this. Just picked up a 2016 rt shaker +, 6 speed. This will get a ton of massaging.
Thanks. Any input?

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Ok I have noticed this on every single vid I see and hear and also have this same issue. I build v twin scoots with tons of hp so this irritates me. The forever time it takes for these engines to come back down to idle. This to me is an issue with not enough fuel at the zero poison in the fuel mapping. This in my opinion is for emissions. So when I get to the point of getting an unlocked ecu and start the tuneing process we will see what we can do about this. Just picked up a 2016 rt shaker +, 6 speed. This will get a ton of massaging.
Thanks. Any input?

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I notice the delayed throttle down on my SC 2015 RT M6. The throttle blade seems to also not completely close (hit its position for idle).

http://www.challengertalk.com/forums/8076633-post15.html
 

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welcome to the world of drive by wire.. it is prevalent in gm, ford, and dodge.. i miss cables.. SO SO much better responce and no screwing around with computer tables for the throttle body
 

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Might want to give Pedal Commander a look.
 
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Discussion Starter #5
welcome to the world of drive by wire.. it is prevalent in gm, ford, and dodge.. i miss cables.. SO SO much better responce and no screwing around with computer tables for the throttle body
I have had other throttle by wire vehicles with out this. I still feel it's either a, fuel issue or maybe they have an idle air valve that is late in closing to help with emissions. I will figure this out in time. Just picker her up so can't do a lot yet because I may be sleeping in the garage if I do lol.

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if you do let me know.. i have got 2800 bucks in tunes on my car.. 6 different tuners.. all respected tuners.. none of them figure it out so if you do, well you are ahead of them
 
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if you do let me know.. i have got 2800 bucks in tunes on my car.. 6 different tuners.. all respected tuners.. none of them figure it out so if you do, well you are ahead of them
I absolutely hate the lingering high idle to normal idle. I do have a wide band air flow set up I will be installing when time permits. These things are invaluable in do it yourself tuning. I also have an email into throttle commander to see about there product.

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I absolutely hate the lingering high idle to normal idle. I do have a wide band air flow set up I will be installing when time permits. These things are invaluable in do it yourself tuning. I also have an email into throttle commander to see about there product.

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A wideband is not going to help diagnose the throttle down. The issue I see is the throttle blade does not completely close and there are 3 distinct throttle down rates in my logs. I do notice if I fatten up the fuel by 20% at the low RPM band the engine reaches idle slightly quicker but it's way too rich though. The diablo trinity tuner will not help fix this as all you can control are fuel and spark advance. I wonder if the HP tuner has more advanced capabilities that can help eliminate this?



BTW I have a couple of tunes from API where they made adjustments that reduced the RPM hang (the first 3 tunes had significant hang time) but as you can see it is not eliminated. Unfortunately I have no way to see what they adjusted.

 

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Discussion Starter #9
A wideband is not going to help diagnose the throttle down. The issue I see is the throttle blade does not completely close and there are 3 distinct throttle down rates in my logs. I do notice if I fatten up the fuel by 20% at the low RPM band the engine reaches idle slightly quicker but it's way too rich though. The diablo trinity tuner will not help fix this as all you can control are fuel and spark advance. I wonder if the HP tuner has more advanced capabilities that can help eliminate this?

FREE How to fix Idle Hang using HP Tuners for GEN III LS vehicles - YouTube


BTW I have a couple of tunes from API where they made adjustments that reduced the RPM hang (the first 3 tunes had significant hang time) but as you can see it is not eliminated. Unfortunately I have no way to see what they adjusted.

Yea I got ya on wide band. Used these a ton when mapping fuel in my v twin motorcycle builds. I like to know what my air-fuel ratios are throughout the RPM range. get it close before I go to the dyno been in tobikes for quite a while, time to play with this Mopar.

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Anyone know if Diablo CMR is able to disable idle cracker/follower like HP tuner? Anyone with HP tuner check to see if this is an option for the hemi?

Also, for those with high RPM hangs after revving....check your intake and throttle body bolts to make sure they are properly torqued (if you see fuel staining around the intake at the heads they might be loose). I just checked the 5.7 intake bolts on my GC and they required about 1/4 turn to hit the correct torque. Much better than the Challenger which required ~2 turns until correct torque was hit.
 

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Was playing around with my tune today. I noticed that if I went 5% richer across the board my throttle would really hang at around 2-3k rpm. At times it almost felt like cruise control was activated and if I had my foot off the pedal long enough it would get to the point where the rpms would finally drop rapidly. I would have expected to do that if I went leaner but not richer. I wish I would have logged this...hopefully it will be nice tomorrow so I can take the car to work again.

I did however log some throttle stabs and it took a whopping 4 seconds for the engine to reach idle after a WOT stab to 5400 RPM.
 

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How are you going rich or lean at low rpm? If you’re in close loop, the pcm is trying to maintain stoich via fuel trims, so i wonder what table(s) are you manipulating to induce this changes? and why those changes would relate to hanging rpm?

And for those on stock tune, is the rpm hanging with the car at idle or during coastdowns ? Do they hang after revving past certain rpm? What model car, auto or m6?

I don’t think I have experienced this condition in my 6 speed 15 Challenger scat, and I’ve been playing with my tune some with HPTuners.
 

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How are you going rich or lean at low rpm? If you’re in close loop, the pcm is trying to maintain stoich via fuel trims, so i wonder what table(s) are you manipulating to induce this changes? and why those changes would relate to hanging rpm?

And for those on stock tune, is the rpm hanging with the car at idle or during coastdowns ? Do they hang after revving past certain rpm? What model car, auto or m6?

I don’t think I have experienced this condition in my 6 speed 15 Challenger scat, and I’ve been playing with my tune some with HPTuners.
I use the trinity to bump the fuel trims. I bumped it to 15% total which resulted in an AFR of ~9.8 (pig rich). Apparently cars today use an idle follower (throttle cracker) which HPT can adjust.

BTW here is a log I performed when I was at 10%.
http://www.challengertalk.com/forums/8081057-post8.html
 

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idle follower and cracker were tables used on 3rd Gen LS1's and their IAC sensors, we have ETC, I have no idea why adjusting fuel trims is messsing with your idle that, but i also figure your tune must be farther away from stock given all the mods you have, so who knows.
We have similar idle airflow tables to control idle airflow like GM did, though i don't see one to control min airflow by rpm, so i guess we have to mess with the proportinal/integral options we have for spark and torque idle.
 

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idle follower and cracker were tables used on 3rd Gen LS1's and their IAC sensors, we have ETC
Just because we have electronic throttle control does not mean the principle is no longer being employed.
https://forum.hptuners.com/showthread.php?20903-Throttle-Follower-and-Cracker
You'll have a little problem under that approach, in GM world RAF is closer to cracker talk, because fueling and mass are calculated from airflow, but I don't see either a cracker table, or RAF table, or anything that could be used in our Dodge approach, there is a desired startup airflow, but that seems time based, so that won't exactly work, plus it seems everything under the Dodge model is torque based, not airflow based.

There are proportional/integral tables to work with spark, and also torque, all based on rpm error, messing with those in the GM approach always gave me issues with idle rpm hanging or engine wanting to stall, RAF for Gen IV lsx engines was all we needed to tame big cams for example, aside from idle/low rpm spark, but we also had timing tables for that, I see none of those in my calibration, instead we have torque base tables vs rpm error that control idle airflow. Way different than GM gen III IAC or gen IV ETC idle tuning.
 

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Dodge model is torque based, not airflow based.
Funny, this guy on the HP tuner forum says the opposite.

https://forum.hptuners.com/showthre...le-programming&p=407536&viewfull=1#post407536
Search for the threads about throttle body airflow, there is one in particular where somebody ask if he could use the Hellcat TB airflow table in his SC R/T, or aftermarket TB I can't remember , and somebody offers an explanation that he should actually make this values a lot smaller, not to model actual airflow, but to make the system believe less airflow is passing by, given the torque based system we have.

I'll see if I can find it tonight, I don't think you can change those values with a handheld device though, but I think I saw you bought hptuners in another thread, so you can give that a try.
 

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Search for the threads about throttle body airflow, there is one in particular where somebody ask if he could use the Hellcat TB airflow table in his SC R/T, or aftermarket TB I can't remember , and somebody offers an explanation that he should actually make this values a lot smaller, not to model actual airflow, but to make the system believe less airflow is passing by, given the torque based system we have.

I'll see if I can find it tonight, I don't think you can change those values with a handheld device though, but I think I saw you bought hptuners in another thread, so you can give that a try.
Appreciate any info you can pass along. BTW I am not trying to be difficult just looking for the right direction...sometimes relying on posts for info is like sifting through sand. :grin2:
 
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