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lynchac12 08-10-2011 07:17 PM

Trans. problems
hello all. I am new to this place but ive been a jeep owner for a long time. I have owned a 99 JGC Limited 4.7 45RFE/247 since 2006. It has 115K. Recently, while driving slow (10-20 MPH) i can let off the gas to coast around a corner, when i go to step on the gas to take off again, the engine will rev for a second and then it will catch gear (should be 2nd or 3rd). It catches kinda hard since i have my foot on the gas. Since i have owned it, there hasnt been any work done on the tranny. It also isnt throwing any codes. Did a tranny service hoping it would fix the problem but it reoccured recently. Thankyou for any help. I always get great info from this website.

Frango100 08-10-2011 09:16 PM

Re: Trans. problems
No check engine light on? Did you do the key dance to see if there is any fault code? The TCM is calculating the shift points depending on several inputs, but even if the gear would change, there should be no big increase in engine rev without acceleration. Or a tranny clutch is slipping, or the problem could be torque converter related. A slipping clutch is normally detected by the TCM and a fault code will be set. Did the tranny service fix the problem for a while?

lynchac12 08-10-2011 09:24 PM

Re: Trans. problems
no codes and the trany service didnt fix anything that i can tell. it doesnt happen all the time, but it should never happen. i forgot to mention, along with this symptom, every once in a while it will jump out of gear at 45-55 mph. i did the key trick a few times and nothing has came up. i thought that most common tranny problems would give a code, but i could be wrong. my trans. also had the TSB to activate the 5th gear, if that helps troubleshooting any.

mandio23 08-10-2011 10:41 PM

Re: Trans. problems
It sound like is the valve body spring plate. This is the most common failure on the 45/ 5-45 transmission. If you plan of fix it yourself, get a 45RFE-HD2 kit comes with a heavy duty spring plate that would not fail like the factory one.

Frango100 08-11-2011 10:40 AM

Re: Trans. problems
My tranny was just rebuild some weeks ago and in the masterkit was also a new spring plate. The old plate was showing a little wear from one of the springs, but nothing abnormal though. Also if the spring plate is the problem, wouldn´t his problem be consistent and not now and then? I would look for an DRBIII scanner, which will show you a lot of info from sensors. When you say that it jumps out of gear, do you mean that the engine freely revs without acceleration? Or does it maybe go into a lower gear? It could be caused by a problem with one of the 2 speed sensors or even the TPS. A wrong input from one of these sensors could make the TCM calculate wrong shift points. The speed sensors however normally give a faultcode.

lynchac12 08-11-2011 12:32 PM

Re: Trans. problems
Is there anyway to test the sensors with a meter? I can also get hold of a better scanner When it jumps out of gear, it either revs freely or jumps to a higher gear. It happens quick so it's kinda hard to tell. I would love to test the sensors before I just start swappin things out. It would also be cool to isolate external things like sensors before I start pulling the valve body off. You guys are awesome

lynchac12 08-11-2011 12:44 PM

Re: Trans. problems
Revs freely or jumps into a LOWER gear. Sorry

Frango100 08-11-2011 05:39 PM

Re: Trans. problems
I would suspect a check engine light when it would rev freely due to a clutch fault. I had it on my tranny that the OD clutch was slipping and it gave me a P0733 code (when i remember well), but at least it knows for which gear which input and output speed it should have, and when slip occurs, it will set a fault. I would not really expect the torque converter, because its normally ok.
So most probably its just going into a lower gear. I see something similar on my Jeep, after i went over a traffic bumb and accelerate. Depending on the speed, it goes into a lower gear and rapidly into higher gear again, giving a certain chunk in the drivetrain. I´m used to it now and accelerate slower after the bumb.

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