NAG 1 Limp Mode Issues

[TransGo Robert]

Man I really was hoping that would fix it but unfortunately it didn't seem to help It continues to go into limp mode after 1 pull. It actually felt decent the first time I drove it after loading the tune in it went through all the gears no problem but the shifts were late for some gears and really early for others. But then as I was cruising along in 5th it popped down into 4th then back into 5th then down to 4th then 3rd and got stuck there. After that, even after restarting the car, it goes into limp mode almost instantly, however, this time, it also goes to to limp mode even if I use manual mode. If it's any help, the tranny I put in is from a 2006 charger rt. I also data logged with as much info as I could while I was out there with the updated ratios.

Bummer so that did not work. Now it calculates the ratios as being 3.633, 2.212 and 1.413 for 1-2-3 which obviously does not match what we entered in the tune so it still sets a ratio code. Without seeing what N2 and N3 read unfortunately it is all a guessing game. Here's are the four possibilities it could be as far as I know. Try the other two and see what if one of them get it right.
Ratios.png

[QuentinC]

I will try all those and see what works, I'm really hoping it's one of those! It is interesting that it is calculating the ratios to be different. Unfortunately, I won't be able to try until these Wednesday. I am going out of town tomorrow morning so as soon as I get back Wednesday, you better believe I will be trying these lol I know I've said it a million times but I really appreciate your help on this issue - without your help I would be high and dry not knowing what to do as this farther than I have ever gone into one specific issue and all relatively new to me.

[TransGo Robert]

I will try all those and see what works, I'm really hoping it's one of those! It is interesting that it is calculating the ratios to be different. Unfortunately, I won't be able to try until these Wednesday. I am going out of town tomorrow morning so as soon as I get back Wednesday, you better believe I will be trying these lol I know I've said it a million times but I really appreciate your help on this issue - without your help I would be high and dry not knowing what to do as this farther than I have ever gone into one specific issue and all relatively new to me.

That's the problem without having the actual N2 and N3 reading, the input speed reading we have on there is a calculated value by the computer based on what it thinks it has in there for gear ratios. This unit is very tricky for that because there is no actually input shaft speed sensor. Here's something that explain one example of the math involved and why it is necessary that will help understand how it works better. It will change of course depending on what ratios you have in the transmission. Unfortunately, all we see in your logs is the calculated RPM the computer is making, we don't get to see the actual real reading to know what ratios you really have in there.
N2 and N3.png

[QuentinC]

I see what you are saying. I guess this is kind of an issue since HP tuners does not seem to support those PID's. I feel like I'm at a standstill without those values. I emailed HP tuners support and got the response I expected - try using the latest beta version of hp tuners to see all available channels for your vehicle. I did get under the car and the serial/part number on the side of the transmission indicates that it is in fact a W5A580. I did try all of the other ratios and the problem persisted.

I did use the bosch scanner a few months back when the problem first started to see if I could find a smoking gun and I just remembered I have pictures of all the readouts it gave me, the N2 and N3 sensor where both on there. However, if I can not data log data then share it, what good is it. The picture I took was with the car idling in park and I did upload it to the drive. The N2 sensor shows 426 rpm and the N3 sensor shows 0 rpm. Obviously that isn't much help given we can't calculate a ratio in park but until I can get my hands on the scanner again (its with a test vehicle right now), this is the best I have.

[TransGo Robert]

I see what you are saying. I guess this is kind of an issue since HP tuners does not seem to support those PID's. I feel like I'm at a standstill without those values. I emailed HP tuners support and got the response I expected - try using the latest beta version of hp tuners to see all available channels for your vehicle. I did get under the car and the serial/part number on the side of the transmission indicates that it is in fact a W5A580. I did try all of the other ratios and the problem persisted.

I did use the bosch scanner a few months back when the problem first started to see if I could find a smoking gun and I just remembered I have pictures of all the readouts it gave me, the N2 and N3 sensor where both on there. However, if I can not data log data then share it, what good is it. The picture I took was with the car idling in park and I did upload it to the drive. The N2 sensor shows 426 rpm and the N3 sensor shows 0 rpm. Obviously that isn't much help given we can't calculate a ratio in park but until I can get my hands on the scanner again (its with a test vehicle right now), this is the best I have.

Bummer that trying all the possibilities did not fix it. But yae, at this point, without being able to read N2 and N3 I don't know where to go with this one. :-(

[QuentinC]

When I am able to get my hands on that bosch scanner, would it be useful if I were able to take a screenshot/picture of the scanner while driving in each gear to get sort of a "snap-shot" of what is happening? Or would that not be of any help? After you explained it to me, I was able to calculate the ratios of each gear that the car was getting but I had to pause the data log at a given point in each gear to get those numbers. Would that same idea apply in this case? I suppose I could also video the screen of the scanner to create my own log lol

[TransGo Robert]

When I am able to get my hands on that bosch scanner, would it be useful if I were able to take a screenshot/picture of the scanner while driving in each gear to get sort of a "snap-shot" of what is happening? Or would that not be of any help? After you explained it to me, I was able to calculate the ratios of each gear that the car was getting but I had to pause the data log at a given point in each gear to get those numbers. Would that same idea apply in this case? I suppose I could also video the screen of the scanner to create my own log lol

Yes it might help, not ideal but better then nothing for sure.

Another way you might be able to solve the enigma here is to log the data after making changes in ratios and also try a few different rear end ratio and see how it reacts as far as the new ratios the computer think it is in each gear. With a couple of different logs for different transmission ratios and couple of different logs with different rear end ratio, I would think you should be able to reverse engineer it so to speak and figure out what each changes make and then change one of the two for something that will make it be happy with the ratios it calculates and not set a code anymore.

[TransGo Robert]

Yes it might help, not ideal but better then nothing for sure.

Another way you might be able to solve the enigma here is to log the data after making changes in ratios and also try a few different rear end ratio and see how it reacts as far as the new ratios the computer think it is in each gear. With a couple of different logs for different transmission ratios and couple of different logs with different rear end ratio, I would think you should be able to reverse engineer it so to speak and figure out what each changes make and then change one of the two for something that will make it be happy with the ratios it calculates and not set a code anymore.

Been thinking about this and I think you should try changing your differential ratio from 3.06 to 3.41 and take a new log. Let me know at it, if it does not fix it, at least it will tell me if I am going in the right direction or not and if how I need to tweak this to fix the problem.

[QuentinC]

I will give it a shot let you know what I can come up with. I am once again out of town (for work, it is a busy time of the year), but will be returning Saturday and will be sure to give it a shot.

Also, I never did log individual changes but the ratio I have programmed in there (3.06) seems to make the car ?happiest?. Going up or down from there only makes the initial 1-2 and 2-3 more delayed/early and throws me into limp mode quicker. I wi give 3.46 a try though, The only higher ratio I tried was 3.55 since that?s what the car had at one time and I thought maybe that would make the computers happy. I will definitely datalog the changes though. Same goes for transmission gear ratios.

[TransGo Robert]

I uploaded a video of what happens when the car goes into limp mode just for reference. I also put in a video of something that I noticed started happening after the issue started. When I put it into manual mode, the gear indicator briefly shows a 5. This is also the case for when I am decelerating and the car is automatically downshifting (while in manual mode), it just shows a "5" until I come to a stop and start accelerating again. I know this info isn't much help but it tells me that the pcm/tcm have some weird electrical issue going on or aren't reading the gear at those times for some reason. I also noticed in the log that it almost immediately shows "unknown" gear as soon as I put it in drive and begin accelerating whereas before it would briefly recognize some of the gears before showing that. This ones tough for sure

Well I had another guy with the same issue that we just resolved today. I ended up making a calculator in Excel that takes everything into account to help sort it out because his was quite complex with a couple of mix match things on that other one. Anyways, it took a long time to created it, but now it makes looking at yours much easier. The problem on yours seems obvious now using this new tool I made, your computer is calculating the OSS RPM based on the speed in MPH as if you had a 2.82 ratio in there instead of 3.06.

For some reason I can't see what gear ratio yours is programed for in your tune, but if you connect your VCM Scanner to the vehicle you should be able to see it, adn if you see that it is set to 2.82, change it to 3.06 and it should fix it. Here's a link to a video that shows how to read and change the ratio using the VCM Scanner: https://www.youtube.com/watch?v=JU8rIuyfpW8

PS According to my new in house made calculator your rear end looks to be 3.23 but since you said it was 3.06 I suggested going with that. But you might want to double check what it really has in there.

[QuentinC]

Ok I see what you are saying, that makes sense then as to why the ratios it was calculating were wrong. So I tried to change it to 3.41 in the VCM scanner like you stated on the previous post and that sets it into limp mode as soon as it grabs 3rd just like before. With 3.23, it seems a little better and does not go into limp mode but also doesn't go past 2nd gear unless I manually shift. However, it seems you're right - 3.06 partially fixed the issue. Now it will shift to second or third in automatic mode but no higher. I can use manual mode to shift into 4th and 5th like before but as soon as I set it back to automatic mode, even if I am cruising in 5th, it'll immediately downshift to 4th then 3rd. It acts as if it is a 3 speed. Also, the shift points are also very high even when I'm giving it minimal throttle. With that being said, I do not get put into limp mode when this happens. I went under the car and counted how many revolutions of the driveshaft made 1 revolution of the wheel. It was just past 3 turns on the dot so I am pretty sure it is a 3.06 as that is the ratio that came in the srt and a common upgrade to do. Also, I had a bad CV axle a while back and when replacing it, I ordered it for a SRT 3.06 rear end instead of the rt 2.82 or 2.62 which have different splines and it fit perfectly.

Also, I uploaded a log with the 3.06 ratio inputted via the vcm scanner into the drive folder. In this specific log, it wouldn't go past second gear on its own so I manually shifted it through all of the higher gears so we can see what ratio it is calculating for each gear. However, it usually shifts to third on its own like I stated. It seems that there definitely is still a ratio/calculation issue that won't allow the trans to shift past 3rd but we are definitely moving in the right direction.

[TransGo Robert]

Ok I see what you are saying, that makes sense then as to why the ratios it was calculating were wrong. So I tried to change it to 3.41 in the VCM scanner like you stated on the previous post and that sets it into limp mode as soon as it grabs 3rd just like before. With 3.23, it seems a little better and does not go into limp mode but also doesn't go past 2nd gear unless I manually shift. However, it seems you're right - 3.06 partially fixed the issue. Now it will shift to second or third in automatic mode but no higher. I can use manual mode to shift into 4th and 5th like before but as soon as I set it back to automatic mode, even if I am cruising in 5th, it'll immediately downshift to 4th then 3rd. It acts as if it is a 3 speed. Also, the shift points are also very high even when I'm giving it minimal throttle. With that being said, I do not get put into limp mode when this happens. I went under the car and counted how many revolutions of the driveshaft made 1 revolution of the wheel. It was just past 3 turns on the dot so I am pretty sure it is a 3.06 as that is the ratio that came in the srt and a common upgrade to do. Also, I had a bad CV axle a while back and when replacing it, I ordered it for a SRT 3.06 rear end instead of the rt 2.82 or 2.62 which have different splines and it fit perfectly.

Also, I uploaded a log with the 3.06 ratio inputted via the vcm scanner into the drive folder. In this specific log, it wouldn't go past second gear on its own so I manually shifted it through all of the higher gears so we can see what ratio it is calculating for each gear. However, it usually shifts to third on its own like I stated. It seems that there definitely is still a ratio/calculation issue that won't allow the trans to shift past 3rd but we are definitely moving in the right direction.

OK progress, it is indeed a 3.06 ratio rear end, it is just about perfect now in the log as you can see in 4th when it is 1 to 1 the input and output RPM are within 10 RPM or so. It is never perfect because the rolling radius of the tires vary with tire inflation adn tire wear. Now the late and no shift past 3rd issue is something else, not sure what it is. I know on those if you have tires that are not all the same diameter or a big difference in pressure it can make the computer think you are cornering and it will not upshift to help prevent losing control, but without the ABS wheel sensor reading in the log I can't tell if that's it. If that's not it then it will most likely be something in the tune, someone with more knowledge than me would have to look at it and figure out what is not set correctly in there.

[QuentinC]

Ok I appreciate all the help, without you I wouldn't have been able to pinpoint the issue this in depth. I really think it is something to do with the diablosport tuner writing the gear ratio to a different line of code and/or module than what HPT does. Looking at some other threads on here, some people have had somewhat similar issues and one guy said it was fixed by using a diablosport tuner to achieve this. I am talking to someone who has an unmarried unit and I am going to try going about it that way. I'll keep you updated on this, I am really hoping this fixes it!

[TransGo Robert]

With 3.23, it seems a little better and does not go into limp mode but also doesn't go past 2nd gear unless I manually shift. However, it seems you're right - 3.06 partially fixed the issue.

That was a silly mistake I made when I came up with 3.23, I went back to see where I had gone wrong and I noticed that I had accidently entered engine RPM instead of input shaft RPM into my calculator, so the math was wrong. That would have only been right if the converter would have been fully locked.

[TransGo Robert]

Ok I appreciate all the help, without you I wouldn't have been able to pinpoint the issue this in depth. I really think it is something to do with the diablosport tuner writing the gear ratio to a different line of code and/or module than what HPT does. Looking at some other threads on here, some people have had somewhat similar issues and one guy said it was fixed by using a diablosport tuner to achieve this. I am talking to someone who has an unmarried unit and I am going to try going about it that way. I'll keep you updated on this, I am really hoping this fixes it!

Sounds good, you are finally getting close at least. Let me know how it turns out.

[z71obs]

The gear ratio is stored in the Front Control module I believe and not the pcm.

[z71obs]

My 2005 300c did the exact same thing as this I bought the car without knowing it had the 3.06 rear end in it. Trans was doing some weird stuff and I reset the adaptives and did the EGS5 Int. Took the car for a ride and it did the same exact thing and same exact code. Being an 05, Hptuners doesn?t allow me to change tire or gear in the scanner for some reason. I ended up having to get a Diablosport i3 to change the gear ratio, tire size, shift points etc. Once I changed it to 2.82 to 3.06 and programmed the tire size I haven?t had issues since. The more I tinker with the transmission side I?m finding that HP tuners almost has little to no effects on adjustments even when the ?write entire? completes.