NAG 1 Limp Mode Issues

Hi all, I have a 2006 charger rt with the beloved NAG1. I've posted a few times before about this but basically, the transmission goes into limp mode after going through the gears. It will get stuck in third gear and will not come out of third until the car is restarted, even after coming to a complete stop. I have replaced and checked ABS sensors (OEM), replaced transmission/torque converter (with new valve body and all related sensors), replaced and programmed new tcm to vin and much more. I only get a P0733 - gear 3 ratio incorrect code. No other related codes.

I did notice when taking a log file, the "trans current gear" channel shows a sporadic reading while everything else like turbine speed seems to be normal. Sometimes, it shows the car's gear and other times shows "unknown". That is the only weird/out-of-place piece of data I can find. I have attached the log and tune file but as a link in a Google Drive folder with public access since HPT forums won't let me upload files into the little drop box thing for some reason. I would appreciate if anyone is willing take a look at the tune and see if they see anything out of place. Also, has anyone ever ran across this before and any ideas why the tranny may not know what gear it's in? Thanks!


Log and tune file are in this drive folder below

https://drive.google.com/drive/folde...jW?usp=sharing

That's usually because someone replaced the rear end with a different ratio or replaced the computer with the wrong ratio programmed in it. You can change that with HP Tuners to match the rear end if yours is has been changed.

I appreciate the response. I did check this. The rear end is a 2.82 and I made sure the computer was programmed to that and the correct tire diameter for my tires was inputted.

Edit: Looking back on this, I meant to say 3.06. I stated that it was a 3.06 in a later comment but in case anyone is reading through this and is wondering, it is a 3.06.

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Originally Posted by QuentinC

I appreciate the response. I did check this. The rear end is a 2.82 and I made sure the computer was programmed to that and the correct tire diameter for my tires was inputted.

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Ok good deal, if you have it programed for 2.82 and it still has the factory 2.82 ratio in there then that's not the problem. To be able to diagnose it we'll need another log but this time with all the transmission parameters recorded. It is crucial to get both N2 and N3 sensor PIDs and all the individual solenoid command PIDs. How did this start by the way, after repair or been working fine for a while and now all of a sudden this?

The problems initially started when I reset the adaptives and performed an egs5x init in the special functions menu. When I purchased the car about a year ago, the transmission did not feel great and the shift points were really early and kind of lazy unless at WOT. I thought that starting fresh and resetting the learned data in the TCM would be harmless and might help a little bit but here we are.

As for logging the individual shift solenoids, I do not see a channel in the drop-down under the TCM tab for shift solenoids. I also do not see anything under the specific name N2/3 sensor. Is there something I'm missing? I believe I am on the most up to date version of the software. I attached a picture in the drive folder of every channel that is available under the TCM.

Also, sorry for my lack of knowledge, I am fairly new to HP tuners as a whole and am just getting into this.

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Originally Posted by QuentinC

The problems initially started when I reset the adaptives and performed an egs5x init in the special functions menu. When I purchased the car about a year ago, the transmission did not feel great and the shift points were really early and kind of lazy unless at WOT. I thought that starting fresh and resetting the learned data in the TCM would be harmless and might help a little bit but here we are.

As for logging the individual shift solenoids, I do not see a channel in the drop-down under the TCM tab for shift solenoids. I also do not see anything under the specific name N2/3 sensor. Is there something I'm missing? I believe I am on the most up to date version of the software. I attached a picture in the drive folder of every channel that is available under the TCM.

Also, sorry for my lack of knowledge, I am fairly new to HP tuners as a whole and am just getting into this.

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I don't know how it looks in HP Tuners, as far as the PIDs are concern. I am use to regular scanner like Snap-On where all the PIDs are there by default. The 722.6 input sensors are a bit tricky, you need to do some math to get the true inputs shaft speed depending on which gear you are in so you need both sensor readings to calculate the ratios. If you can't read that with HP Tuners (it would really surprise me) then you will need a different scanner.

Ok I see. I have access to a Bosch scanner which should definitely be able see those. I?m not sure if it can log data but I?ll give it a shot when I can get my hands on it. Thanks for your help so far, I?ll check back in when that happens.

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Originally Posted by QuentinC

Ok I see. I have access to a Bosch scanner which should definitely be able see those. I?m not sure if it can log data but I?ll give it a shot when I can get my hands on it. Thanks for your help so far, I?ll check back in when that happens.

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Yes the BOSH scanner will show you all the PIDs, however it will not let you share a log viewable others only Snap-On and HP Tuners have that feature. I would be floor if you could not see those essential and basic parameters with HP Tuners. I would email their product support team to see what they say. I am very familiar with reviewing and analyzing logs but I just about never get to use HP Tuners to log data myself, so I can't offer any help with where to go to find those missing PIDs in there.

Understandable, I appreciate your insight. I will send their support an email and see what I can find out.

What has me racking my brain is the fact that I have replaced the transmission, tcm, valve body with new conductor plate in the old transmission, and the issue has not gone away but more importantly it has not changed at all. That's 3 sets of solenoids, speed sensors, and valve bodies total. I do want data regarding the N2/N3 sensors in the transmission as well as the individual shift solenoids and will get it and report back as I feel that it is really important as well.

I think I mentioned it in an older post but not this one; I can go through all the gears in manual mode however it still ends up getting stuck in third. In automatic mode, it happens right away as you saw in the data log and I explained. But in "autostick" I can get it to shift to 5th on the first acceleration after restarting the car and it will stay in 5th for about 3-5 seconds but then it automatically kicks down to 4th then 3rd right away and gets stuck there until car is restarted. So that tells me the solenoids are at least working in that sense. Do you think it could possibly be a bad PCM? It sounds out there given the issue but that's really one of the only things I haven't replaced thus far.

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Originally Posted by QuentinC

What has me racking my brain is the fact that I have replaced the transmission, tcm, valve body with new conductor plate in the old transmission, and the issue has not gone away but more importantly it has not changed at all. That's 3 sets of solenoids, speed sensors, and valve bodies total. I do want data regarding the N2/N3 sensors in the transmission as well as the individual shift solenoids and will get it and report back as I feel that it is really important as well.

I think I mentioned it in an older post but not this one; I can go through all the gears in manual mode however it still ends up getting stuck in third. In automatic mode, it happens right away as you saw in the data log and I explained. But in "autostick" I can get it to shift to 5th on the first acceleration after restarting the car and it will stay in 5th for about 3-5 seconds but then it automatically kicks down to 4th then 3rd right away and gets stuck there until car is restarted. So that tells me the solenoids are at least working in that sense. Do you think it could possibly be a bad PCM? It sounds out there given the issue but that's really one of the only things I haven't replaced thus far.

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I thought all you had done was reset the adaptive, I should have asked for the whole story instead of just how it started. In any event, this is not going to be a transmsision issue (or super unlikely i should say) either the ratio is calculated incorrectly or the computer has the wrong ratio in it for the unit you have in or the rear end ratio that is in it. If I can read N2 and N3 I can tell you real quick, but without that I am in the dark unfortunately. To me this screams the super common computer vs rear end ratio mismatch issue. I would guess that what happened is that the programing got corrupted somehow when you did the adapt reset and you have been chasing that ever since. I could not see in your tune where it says what ratio it is expecting, not sure if that's stored somewhere else or if I am just blind and can't find it but I sure would have like to verify that indeed it had 2.82 ratio in there. The fact that you can get it working a bit in manual mode is what they all do when there is a ratio mismatch, the command is slightly different in manual mode and the criteria for setting the code(s) are also a bit different that's the reason why it does that.

I'm sorry for the confusion. At this point I have picked so many people's brains on this problem that I forget what I tell to who. I did put the info in a previous post but I guess I should have just started fresh, that is my bad. I do not see in the tune file where it has an expected gear ratio either, it is not just you. The only time I can see the gear ratio is if I use the VCM editor to connect to the car and go into the "special functions" tab and complete a "gear tire adjustment". I have a 98 trans am as well and looking at that hpt file, the gear ratio and tire size is clear as day under the speedometer tab in the file. I do find that really weird. I wonder if this is a thing with the Chrysler PCM's not having gear ratio in the tune file or if HPT doesn't show it for some reason. I think you have a really good theory, I just don't know what do to from here. I will get that data on those sensors once I have access to the bosch scanner, it is at the place I work but currently being used so once they are done with it I will snag it and get that information.

Since this transmsision does not have an output sensor, it relies on the ABS rear wheel(s) speed sensor to calculate the output shaft RPM based on the ratio it is told that it has in it. So I would assume that the ratio is probably stored in the ABS computer since we don't see it in the transmsision side. But that's just a guess on my part of course. But I really think that's the difference and why in your Trans am the ratio is there since it it has an output shaft sensor dn does not need to do any math to converter it or relay on another computer to get the signal from, the ratio is only used to calculate the vehicle speed in miles per hours using the ratio and tire sizes provide. This application works the opposite way. It gets the axel RPM then does the math using the rear end ratio in its table to figure out what the output shaft RPM is.

Ah, that makes a lot of sense. I did not realize it did not have an output speed sensor but now that you mention it makes perfect sense why these cars are so finnicky about abs sensors. I think you are definitely on to something with that, especially given the situation I am about to explain.

It's a long story but basically I found a build thread on my exact car from back in 2012. It used to have a dynatrac 60 rear end in it which is really an dana60 center section made to fit into the lx platform irs. Super expensive and super overkill for the cars modest power level. However, when I bought the car, it had this 3.06 srt rear end in it. I am guessing that one of the owners between him and I ripped it out and sold it realizing that it was overkill and a lot money on the table or maybe it had a problem and was a lot of money to fix. The build thread did state that it was a 3.55 rear gear ratio. With all this being said, it also had a diablosport predator hand-held tuner.

When I first started messing with the car in HP tuners, going into the gear tire adjustment special functions menu, it stated that the rear end was a 2.82 ratio which is what came in the car factory. I'm thinking the diablosport must have programmed it elsewhere (such as the abs module like you stated) and when I reset and initialized everything to the 3.06 gear ratio that the car actually has now, it realized that the abs module or wherever else the predator programmed the 3.55 into was different. So basically I need to figure out if that is the case and how to remedy this without buying a diablosport tuner.

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Originally Posted by QuentinC

Ah, that makes a lot of sense. I did not realize it did not have an output speed sensor but now that you mention it makes perfect sense why these cars are so finnicky about abs sensors. I think you are definitely on to something with that, especially given the situation I am about to explain.

It's a long story but basically I found a build thread on my exact car from back in 2012. It used to have a dynatrac 60 rear end in it which is really an dana60 center section made to fit into the lx platform irs. Super expensive and super overkill for the cars modest power level. However, when I bought the car, it had this 3.06 srt rear end in it. I am guessing that one of the owners between him and I ripped it out and sold it realizing that it was overkill and a lot money on the table or maybe it had a problem and was a lot of money to fix. The build thread did state that it was a 3.55 rear gear ratio. With all this being said, it also had a diablosport predator hand-held tuner.

When I first started messing with the car in HP tuners, going into the gear tire adjustment special functions menu, it stated that the rear end was a 2.82 ratio which is what came in the car factory. I'm thinking the diablosport must have programmed it elsewhere (such as the abs module like you stated) and when I reset and initialized everything to the 3.06 gear ratio that the car actually has now, it realized that the abs module or wherever else the predator programmed the 3.55 into was different. So basically I need to figure out if that is the case and how to remedy this without buying a diablosport tuner.

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Ok I think i figured it out, if you still have the factory size tires the OSS calculation is spot on. What is not right is each individual gear ratios, the transmission you have in there is not the same ratio as what the factory one was or what you have in your tune. I did some match channels and I think this should be easy to fix. The transmission that was in that vehicle based on the VIN originally was a W5A 580. The ratios are 3.5876, 2.1862, 1.4054, 1.0000 and 0.8314 for gear 1-2-3-4-5 for that one. That's what you have as well entered in your tune (see image). Now the ratios you have when doing the math using the log you send and the calculated turbine shaft RPM in there (calculated value from N2 and N3) for the first three gear are: 3.991, 2.393 and 1.532. This is real close to the gear ratios of the W5A 330 version which is 3.9510, 2.4233, 4.4857, 1.0000, and 0.8331. In the tune they seem to be rounding off the ratios to two digits after the decimal point, so if you replace the ratios in there for the following it should fix it: 3.95, 2.42, 1.49, 1.00 and 0.83 for 1-2-3-4-5. Oh and reverse needs to change to 3.15 instead of 3.17. Give that a try and let me know.
Attachment 144084

I asked before but asked someone else by accident. Does it still have the factory tire size (P225/60R18)?

Hmm very interesting. I appreciate the continued help I will try that shortly and get back to you. The tire size is 245/45/20 which is a tenth of an inch off the stock 18 inch rim size (28.7" vs 28.6") which I think should be fine(?) Again I really appreciate it I will get back to you shortly.

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Originally Posted by QuentinC

Hmm very interesting. I appreciate the continued help I will try that shortly and get back to you. The tire size is 245/45/20 which is a tenth of an inch off the stock 18 inch rim size (28.7" vs 28.6") which I think should be fine(?) Again I really appreciate it I will get back to you shortly.

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Definitely not enough of a difference to affect anything. When I did the math the OSS RPM was almost a perfect match to the VSS and ghay's never that precise in the first place, it varies with tire brands, air pressure and wear. Entering the ratios for the transmission you put in will fix this I am 99.9% sure.

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.

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

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Originally Posted by QuentinC

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.

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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.
Attachment 144096

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.

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Originally Posted by 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.

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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.
Attachment 144129

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.

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Originally Posted by 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.

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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. :-(

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

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Originally Posted by 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

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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.

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Originally Posted by 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.

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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.

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.

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Originally Posted by QuentinC

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

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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.

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.

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Originally Posted by 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.

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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.

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!

Quote:

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Originally Posted by QuentinC

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.

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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.

Quote:

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Originally Posted by 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!

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

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

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.