Problem with 3-4 shift
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From: Zurich - Switzerland
Problem with 3-4 shift When my A4 shifts from 3rd to 4th between 40 and 70 mph at part throttle it “looses” the gear for a moment (see the graph). The engine revs about 200 rpm higher during a very short time than goes down where it should. This takes less than half second but I can hear and feel it.
This happens only if the car accelerates just a little (15 – 20% TPS), with more torque it shifts just fine. The same happens if I shift manually.
The car has about 40’000 mi, the transmission fluid is fine (color, level), mods are just a FIPK and LT’s.
The stock shift time is 0.5 seconds; I’ve set it first at 0.7 then at 0.3 to see if it changes… still the same.
This problem happens when the transmission temperature is at the normal working level (220F), with a cold transmission (80F) this doesn’t happen.
Who could give me some idea to solve this problem? I always wanted to replace my A4 with a M6… but not exactly now!
Thanks - Stefano
This happens only if the car accelerates just a little (15 – 20% TPS), with more torque it shifts just fine. The same happens if I shift manually.
The car has about 40’000 mi, the transmission fluid is fine (color, level), mods are just a FIPK and LT’s.
The stock shift time is 0.5 seconds; I’ve set it first at 0.7 then at 0.3 to see if it changes… still the same.
This problem happens when the transmission temperature is at the normal working level (220F), with a cold transmission (80F) this doesn’t happen.
Who could give me some idea to solve this problem? I always wanted to replace my A4 with a M6… but not exactly now!
Thanks - Stefano
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From: Long Island, NY
im not sure why you're having this problem the thing that got my attention was that 220 degree "normal operating temp"....220 degrees is WAYYYY too hot for a 4L60E thats being driven normally. you should be just approaching 200 degrees when you beat on the car for awhile. at that temperature, the trans is not going to live long. you may have a slightly burnt clutch pack that is causing that momentary slip.
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From: Zurich - Switzerland
OK let me chech the temperature again: 'cause I think in Celsius I maybe made a too rough "translation".
Time to install a cooler?
If the clutch pack is slightly burned is it only at the surface and (happily) go away?
Time to install a cooler?
If the clutch pack is slightly burned is it only at the surface and (happily) go away?
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From: Long Island, NY
a cooler is always good to have but if u are even above 200 degrees at all, you are in DESPERATE need of one! these trannies HATE heat. 200+ degrees will spell the end of a 4L60 in no time.
as for the burnt clutch packs...if you've ever seen one of these clutches, there isnt a lot of material on them, if they've been damaged by the heat, they're going to need replacement one way or another. you may get away with it for awhile, but if you really are running THAT hot, you may be in trouble.
as for the burnt clutch packs...if you've ever seen one of these clutches, there isnt a lot of material on them, if they've been damaged by the heat, they're going to need replacement one way or another. you may get away with it for awhile, but if you really are running THAT hot, you may be in trouble.
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From: Zurich - Switzerland
Convinced!
I already saw a couple of coolers. There is one with an orifice: it allows more oil to go trough at higher temperatures. Do you think it's necessary? Or can I just buy an industrial heat hexchanger of the same size as for car applications?
I already saw a couple of coolers. There is one with an orifice: it allows more oil to go trough at higher temperatures. Do you think it's necessary? Or can I just buy an industrial heat hexchanger of the same size as for car applications?
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From: Zurich - Switzerland
OK i checked the trans temp again: 230F!
This with an air temperature of 90F and driving around "like a normal person".
I went to a local GM garage: apparently it's a must here to have a trans cooler. Many hills and about 85 mph on the highway.
He tolde me to eliminate TCC and see what happens...
This with an air temperature of 90F and driving around "like a normal person".
I went to a local GM garage: apparently it's a must here to have a trans cooler. Many hills and about 85 mph on the highway.
He tolde me to eliminate TCC and see what happens...
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From: Doniphan, MO
FWIW, the 'flare' going from 3-4 MANUALLY @ light throttle is due to the way the PCM is set up. The dealer told me this @ around 15,000 miles, when I first complained. I did not believe him!
Anyway, last Sept. I was at the "Motive Power" show in Nashville and asked the NOT PAID BY GM industry 'gurus' about this and was told the same thing. By then, with 50,000+ miles, the T/A had begun doing it on rare occasion when left in OD. Once again, the comment was, "With that mileage, it is not considered a failure contributing problem! If it happens above 15-20%TPS, there IS enough slippage to be considered as a factor in eventual failure."
As far as trans temp is concerned, most of the guys around here don't seem to have any problem keeping the temp well below 200°.
Good luck
Anyway, last Sept. I was at the "Motive Power" show in Nashville and asked the NOT PAID BY GM industry 'gurus' about this and was told the same thing. By then, with 50,000+ miles, the T/A had begun doing it on rare occasion when left in OD. Once again, the comment was, "With that mileage, it is not considered a failure contributing problem! If it happens above 15-20%TPS, there IS enough slippage to be considered as a factor in eventual failure."
As far as trans temp is concerned, most of the guys around here don't seem to have any problem keeping the temp well below 200°.
Good luck
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From: Zurich - Switzerland
Originally Posted by A BAD T/A
FWIW, the 'flare' going from 3-4 MANUALLY @ light throttle is due to the way the PCM is set up. The dealer told me this @ around 15,000 miles, when I first complained. I did not believe him!
Anyway, last Sept. I was at the "Motive Power" show in Nashville and asked the NOT PAID BY GM industry 'gurus' about this and was told the same thing. By then, with 50,000+ miles, the T/A had begun doing it on rare occasion when left in OD. Once again, the comment was, "With that mileage, it is not considered a failure contributing problem! If it happens above 15-20%TPS, there IS enough slippage to be considered as a factor in eventual failure."
As far as trans temp is concerned, most of the guys around here don't seem to have any problem keeping the temp well below 200°.
Good luck
Anyway, last Sept. I was at the "Motive Power" show in Nashville and asked the NOT PAID BY GM industry 'gurus' about this and was told the same thing. By then, with 50,000+ miles, the T/A had begun doing it on rare occasion when left in OD. Once again, the comment was, "With that mileage, it is not considered a failure contributing problem! If it happens above 15-20%TPS, there IS enough slippage to be considered as a factor in eventual failure."
As far as trans temp is concerned, most of the guys around here don't seem to have any problem keeping the temp well below 200°.
Good luck
If I add an additional cooler, does it go after or instead the stock cooler?
Instead it will be cooler, but in winter maybe too cold, or not??
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I might expect to see flare like that if we were looking at a 2-3 shift when the band has to let go and the 3-4 clutch has to engage. In that scenario if the band was releasing too early you see a graph exactly like that and it would feel like a moment of neutral between gears because it would be in first, allowing overrun.
In your case, being a 3-4 shift, there are only three possibilities that I can think of. For one if could be that the converter was locked and became unlocked for the shift. That would seem to be a programming problem or bad TCC solenoid causing the TC clutch to drag. Another possibilty is that the 3-4 clutch is pack is slipping. If it's the TC doing it you'd be able to see this on the scanner. If the 3-4 clutch is the cause it won't set an error but it cound mean that the clutch surfaces are burnt and have reduced holding capability. This could also be brough on by mods allowing less TPS to make more torque than before resulting in line pressure inadequate to hold the 3-4 clutches as the shift takes place. (Larger throttle bodies can do it) When the band engages for the 3-4 it loads up the 3-4 clutch pack with instantaneous torque as the engine is brought down in RPM by the shift. Programming can fix this by raising line pressure vs TPS for third and fourth gear.
In your case, being a 3-4 shift, there are only three possibilities that I can think of. For one if could be that the converter was locked and became unlocked for the shift. That would seem to be a programming problem or bad TCC solenoid causing the TC clutch to drag. Another possibilty is that the 3-4 clutch is pack is slipping. If it's the TC doing it you'd be able to see this on the scanner. If the 3-4 clutch is the cause it won't set an error but it cound mean that the clutch surfaces are burnt and have reduced holding capability. This could also be brough on by mods allowing less TPS to make more torque than before resulting in line pressure inadequate to hold the 3-4 clutches as the shift takes place. (Larger throttle bodies can do it) When the band engages for the 3-4 it loads up the 3-4 clutch pack with instantaneous torque as the engine is brought down in RPM by the shift. Programming can fix this by raising line pressure vs TPS for third and fourth gear.
What kind of tuning do you have done, whats your minimum 4th gear speed set at. Sometimes people raise them and forgot to change the 3rd gear TC lockup speed. Its possible that its locking in 3rd and when it comes time for 4th gear(od) the TC is unlocking to shift causing the momentary bump in rpm. All of this assumes you did some kind of tuning though. if its still stock, and it really is at 220 degrees, it sounds FUBAR
Originally Posted by tici
If I add an additional cooler, does it go after or instead the stock cooler? Instead it will be cooler, but in winter maybe too cold, or not??
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From: Zurich - Switzerland
Thanks guys for your answers!
My mods are (for now) LT's and a FIPK. Nothing crazy.
About the transmission settings: the original shift speeds are stock, same for the TCC apply / release speeds, but I noticed something strange (to me): the 3rd TCC apply speed is the same as the 3-4 shift speed, this for the range 12-31 TPS%.
At more than 25% TPS the 4th TCC apply speed is lower than the 3rd TCC apply speed.
During a slight acceleration it means: 2-3 without TCC, in 3rd it apply TCC, release it to shift, shift 3-4, locks it.
Is it normal? Do I really need TCC in 3rd? I can also put the 3rd TCC speeds at 255 mph and forget it...
I wanted to replace transmission fluid and filter, at the same time replace the 1-2 solenoid (it also shifts 3-4), the TCC solenoid and the TCC Pulse Width Modulator.
Is it worthed to replace all this?
The TCC solenoid doesn't come alone but with the complete harness... ($$$)!
James: this of increasing the line pressure is a good idea, I'll try it.
Thanks - Stefano
My mods are (for now) LT's and a FIPK. Nothing crazy.
About the transmission settings: the original shift speeds are stock, same for the TCC apply / release speeds, but I noticed something strange (to me): the 3rd TCC apply speed is the same as the 3-4 shift speed, this for the range 12-31 TPS%.
At more than 25% TPS the 4th TCC apply speed is lower than the 3rd TCC apply speed.
During a slight acceleration it means: 2-3 without TCC, in 3rd it apply TCC, release it to shift, shift 3-4, locks it.
Is it normal? Do I really need TCC in 3rd? I can also put the 3rd TCC speeds at 255 mph and forget it...
I wanted to replace transmission fluid and filter, at the same time replace the 1-2 solenoid (it also shifts 3-4), the TCC solenoid and the TCC Pulse Width Modulator.
Is it worthed to replace all this?
The TCC solenoid doesn't come alone but with the complete harness... ($$$)!
James: this of increasing the line pressure is a good idea, I'll try it.
Thanks - Stefano
Here's a place that would have some answers. Nice guys also.
http://www.transmissioncenter.net/4L60E.htm
http://www.transmissioncenter.net/4L60E.htm
I turned off my TCC apply throughout 3rd.
The stock 4th gear TCC apply line is funny,
it crosses the up/downshift line twice (lock
at low pedal, unlock at mid pedal, relock at
high pedal / high speed). I stayed with this
scheme but altered it to track what I did
with shiftpoints.
There is no good reason for an orifice in the
transmission cooler line except maybe arctic
conditions, if the "orifice" is really thermostatic.
But I'd say, stay away from foolery and get
a nice clean finned tube. I put my cooler first,
then to the radiator heat exchanger. But I run
my low speed fans full time and high speed
not too far behind (179F ECT ON temp) so the
radiator tank is kept pretty cool.
I agree that you should (temporarily) turn off
3rd gear TCC lock and see if the "flare" goes
away (like, is the RPM pre-shift now all at the
same level as the flare peak as would come off
the TCC slip-at-load?). If you still see a flare
above the line w/o 3rd locked then you'd have
to suspect internal mis-synchronization of the
release / apply events (which I gather are
quite "busy" compared to other, simpler trannies).
The stock 4th gear TCC apply line is funny,
it crosses the up/downshift line twice (lock
at low pedal, unlock at mid pedal, relock at
high pedal / high speed). I stayed with this
scheme but altered it to track what I did
with shiftpoints.
There is no good reason for an orifice in the
transmission cooler line except maybe arctic
conditions, if the "orifice" is really thermostatic.
But I'd say, stay away from foolery and get
a nice clean finned tube. I put my cooler first,
then to the radiator heat exchanger. But I run
my low speed fans full time and high speed
not too far behind (179F ECT ON temp) so the
radiator tank is kept pretty cool.
I agree that you should (temporarily) turn off
3rd gear TCC lock and see if the "flare" goes
away (like, is the RPM pre-shift now all at the
same level as the flare peak as would come off
the TCC slip-at-load?). If you still see a flare
above the line w/o 3rd locked then you'd have
to suspect internal mis-synchronization of the
release / apply events (which I gather are
quite "busy" compared to other, simpler trannies).
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From: Zurich - Switzerland
This of the orifice is what I saw on the Transmission Section of one of the sponsors on the right... It's a B&M SuperCooler 24,000 GVW. It's already ordered (and paid). We'll see how it works.
No flare without 3rd TCC! It's a funny driving: very smooth. The bad thing is that driving downhill the engine won't brake the car. You also have to "help" the transmission to go in 4th (just go back a little with the pedal).
What was your reason to eliminate 3rd TCC?
I'll soon receive a supercharger ("only" 5-6 PSI boost). Is it a good thing to eliminate TCC? Does it help to don't kill the tranny?
No flare without 3rd TCC! It's a funny driving: very smooth. The bad thing is that driving downhill the engine won't brake the car. You also have to "help" the transmission to go in 4th (just go back a little with the pedal).
What was your reason to eliminate 3rd TCC?
I'll soon receive a supercharger ("only" 5-6 PSI boost). Is it a good thing to eliminate TCC? Does it help to don't kill the tranny?
