NAG 1 Limp Mode Issues

[QuentinC]

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

[TransGo Robert]

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.

[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.

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.

[TransGo Robert]

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.

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?

[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.

[TransGo Robert]

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.

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.

[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.

[TransGo Robert]

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.

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.

[QuentinC]

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

[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.

[TransGo Robert]

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.

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.

[QuentinC]

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.

[TransGo Robert]

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.

[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.

[TransGo Robert]

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.

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.
Ratio.png

[TransGo Robert]

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

[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.

[TransGo Robert]

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.

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.

[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.

[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