Couple questions from a nervous father

stoutdog · **Posted:** Thu Jul 09, 2009 6:18 pm

Hey all, my dad and I both own KJ CRDs (woot!). His is an '05, mine an '06. He had a few questions that I thought I knew the answer to but wanted to run by y'all:

1) My Jeep shifts at 10-20-35-53-64 (OD) and his at 10-20-35-50-58 (OD). He wants to take the Jeeps by a dealer to see if one has the wrong shift points somehow.... I told him that unplugging the battery on mine (which I just bought, used) for 30 minutes or so and plugging it back in would allow the transmission to "learn" my own shift points and fix the issue. Am I correct or crazy?

2) On a side note, he said the dealer wanted to mess with the TCM, possibly flashing it. I should say no to this, right? I don't wanna castrate my Jeep

3) Anybody ever hear of an ECU crapping out? He's worried that, if I get GDE and then they somehow go under, my ECU might die and I would've lost my investment... Nervous, eh?

Thanks y'all!

ATXKJ · **Posted:** Thu Jul 09, 2009 6:35 pm

Check his VIN vs the Jeep website for recalls - I suspect it has not had the F37 - which is a good thing
F37 will make it overrev on each shift and kill performance

best bet - get a spare TCM from a junkyard - take it in - let them flash the spare - and change the Torque Converter
and then put the good TCM back in - it'll run better.

(Shift points are controlled by the TCM - there is a learning effect - but it doesn't change the speed that much)

the ECU is a computer - computers can die - although the expected lifespan is 20+ years - or if you jump start the wrong way I'll update the post if I can find the link

I think GDE will reflash if the the ECU gets changed - call them and verify

FYI Mackruss - had the ECU problems - he had a couple of posts about it
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?t=38937&postdays=0&postorder=asc&highlight=blown+ecu&start=0

stoutdog · **Posted:** Thu Jul 09, 2009 6:42 pm

ATXKJ wrote:

Check his VIN vs the Jeep website for recalls - I suspect it has not had the F37 - which is a good thing
F37 will make it overrev on each shift and kill performance

best bet - get a spare TCM from a junkyard - take it in - let them flash the spare - and change the Torque Converter
and then put the good TCM back in - it'll run better.

(Shift points are controlled by the TCM - there is a learning effect - but it doesn't change the speed that much)

the ECU is a computer - computers can die - although the expected lifespan is 20+ years - or if you jump start the wrong way I'll update the post if I can find the link

He ('05) does have F37, unfortunately. My Jeep ('06) is the one that insists on going to 64mph before dropping into overdrive... The '06 doesn't have to go in for an F37, does it? We checked the VIN and there was no mention of it. I presume it should be shifting into OD around 58 or so?

Why would I want to replace the TC and keep the TCM? I was under the impression that the new TC would decrease performance. Sorry, I'm a little tired and new to this whole thing...

ATXKJ · **Posted:** Thu Jul 09, 2009 6:47 pm

The new TC is only slightly different from the old - but it's new - and it doesn't effect the shift points - the TCM controls those.

The Suncoast will have enough of a difference to feel it - but it still doesn't change the shift points.
gmctd thinks the Hemi version might - but I don't think anyone's installed one

stoutdog · **Posted:** Thu Jul 09, 2009 6:54 pm

ATXKJ wrote:

The new TC is only slightly different from the old - but it's new - and it doesn't effect the shift points - the TCM controls those.

The Suncoast will have enough of a difference to feel it - but it still doesn't change the shift points.
gmctd thinks the Hemi version might - but I don't think anyone's installed one

Ahh okay, I see what you are saying now... I'm not looking for a new TC, not worried about that as I only plan some minor mods.

So I should allow the dealer to reflash the TCM to correct the high shift points on my ('06) CRD?

CATCRD · **Posted:** Thu Jul 09, 2009 7:40 pm

If his final shift points are at 50 and 58 then most likely he does not have the full F37 flash and he should be thankful. Those are my exact shift points, and I don't have F37.

They can't correct your high shift points. If you took your dad's in and they flashed it to the most recent software, it would have the same shift points as yours.

Joe Romas · **Posted:** Thu Jul 09, 2009 7:58 pm

stoutdog wrote:

So I should allow the dealer to reflash the TCM to correct the high shift points on my ('06) CRD?

HOLD ON A SECOND!!!!! PLEASE READ CAREFULLY :lol:

Your 06 has the later shift points because yours has had F37 done or some form of it. (there was one before f37 that did it too that also caused third party scanners to not work) The only way your going to get the earleir shift points is to "borrow" permently the TCM out of your dad's 05 that has not had F37 based on what your saying his shift points are.

F37 CAUSES THE LATER SHIFT POINTS :shock: Don't under any circumstances let any dealer touch your dad's TCM that has the early shift points because it has not had the F37 castration done to it, it's gold

....... Yours with the later shift points has already been "deflowered" so let them do whatever they want :lol:

As for the green diesel tune go for it

ATXKJ
The "slightly" different part on the older torque converters is what explodes :shock:

The replacements don't have that part in them. Newer torque converters have not been failing, just original ones in the 05 and early 06 models made before November 05. But as you say they don't change shift points eather way.

stoutdog · **Posted:** Thu Jul 09, 2009 9:56 pm

Joe, thanks. Well, that sucks. I'm trying to get a hold of my VIN to check on this (my Jeep is in another state right now...). No wonder F37 is awful, shifting into 5th at 64 is ridiculous. Grr.

How would I know if I have the late model TC?

nursecosmo · **Posted:** Fri Jul 10, 2009 12:05 am

I might be off on this one, but I don't think that unhooking the battery would have any effect the shift points. As far as I know, the transmission map is stored in an EEPROM chip, and as such is non-volatile memory.

Turbo Tim · **Posted:** Fri Jul 10, 2009 12:46 am

Yo Wait. When you get back to AZ, give me a call. We can put my F37ed TCM in your CRD and see how you like it.
I'll be glad to trade ya, or do a test? Let me know.

nursecosmo · **Posted:** Fri Jul 10, 2009 1:07 am

It's very strange that this subject of shift points comes up again. It seems that everyone has different shift points. I've had the F37 and I shift at 10 20 35 50 60 pretty much on the money. wierd huh?

Uffe · **Posted:** Fri Jul 10, 2009 2:30 am

Rofl - my 03 CRD shifted into 5th at 62mph and it had 4.10 diff ratios

High rpm shift points? Yes please.

danoid · **Posted:** Fri Jul 10, 2009 9:41 am

Do not mix model years of transmission controllers. The TCM -> rest of vehicle communications are different between model years and undesireable results will occur.

The shift schedules were different between 05 and 06 when they were initially released. The subsequent software releases further complicated matters.

As a reminder also, 4th gear is 'overdrive' being a 0.75:1 gear ratio. 5th gear is 0.69:1. In practice engine rpms move what, 100-200 rpm? Really doesn't make a difference unless you're towing. I'd rather see 5th gear pushed out to 69-70 mph so I could tow at 65 in 4th.

ChesterCRD · **Posted:** Fri Jul 10, 2009 10:07 am

I'm not sure how relevant this is, but I'll throw it out there for what it's worth.

On occasions when I run dinodiesel I get my 5th gear shift right at 59 mph. When I run high ratios of biodiesel my 5th gear shift is later...up around 65 mph. My assumption is that TCM relearns based on the slightly lower power output of engine when running B99. If this is the case, then shift points would change with fuel quality and possibly driving style.

There are plenty on the board who know a lot more about our transmission and TCM than I do though.

vegiH · **Posted:** Fri Jul 10, 2009 10:43 am

+1 bio fuel theroy,Mine shift @ 59 on #2. when I don't have any WVO filtered I put #2 in my WVO tank and this is what I have found to be true,64 MPH on WVO 59mph on #2.When I tow heavy I add some #2 to my WVO and I cruise @62mph in 4th gear.How can you tell if you have been f37ed or not.I ask because I tow alot with my rigs and like to add some more power without grenading the tranny or tc...............H

CATCRD · **Posted:** Fri Jul 10, 2009 10:47 am

vegiH wrote:

+1 bio fuel theroy,Mine shift @ 59 on #2. when I don't have any WVO filtered I put #2 in my WVO tank and this is what I have found to be true,64 MPH on WVO 59mph on #2.When I tow heavy I add some #2 to my WVO and I cruise @62mph in 4th gear.How can you tell if you have been f37ed or not.I ask because I tow alot with my rigs and like to add some more power without grenading the tranny or tc...............H

Go to the Jeep website, owner's area, recalls page. Enter your VIN digits and it will tell you if there are any outstanding recalls. Since yours is an 05 it was affected by F37. If it doesn't appear on that page it was done. Odds are it was, because your final shift point is so high, but I think that came with the F31 flash too.

gmctd · **Posted:** Fri Jul 10, 2009 11:57 am

Minor shift-point variations are resulted from actual tire diameter, incl tire pressure, and the programmed tire size\diameter in computer - mine is in OD well B4 TCC lock at 54mph and stays in lock till just below 52mph - I have Suncoast\Transgo and 2.55's and reset the computer for tire diameter, as 2.55's are not listed

linewarbr · **Posted:** Fri Jul 10, 2009 12:56 pm

gmctd wrote:

Minor shift-point variations are resulted from actual tire diameter, incl tire pressure, and the programmed tire size\diameter in computer - mine is in OD well B4 TCC lock at 54mph and stays in lock till just below 52mph - I have Suncoast\Transgo and 2.55's and reset the computer for tire diameter, as 2.55's are not listed

You have 2.55 rear gearing? What is stock rear gearing?

CATCRD · **Posted:** Fri Jul 10, 2009 2:23 pm

I think he means 255 wide tires. mm.

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

linewarbr wrote:

gmctd wrote:

Minor shift-point variations are resulted from actual tire diameter, incl tire pressure, and the programmed tire size\diameter in computer - mine is in OD well B4 TCC lock at 54mph and stays in lock till just below 52mph - I have Suncoast\Transgo and 2.55's and reset the computer for tire diameter, as 2.55's are not listed

You have 2.55 rear gearing? What is stock rear gearing?

Stock is 3.73 I believe.

Couple questions from a nervous father

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