4l60e trans prob after rebuild
04-29-2013, 08:09 PM
#1
4l60e trans prob after rebuild 2000 camaro z28 auto. So I lost 3rd and 4th gear. So I dropped the trans and had it rebuilt. After Install I made a new tune setting all trans settings at stock, has a 2200 trailblazer torque converter, as I drove it for a while it seems that it sliping pretty bad and half the time full throttle won't rev past 3000rpms.. So I tried puting a full stock tune on and it had full power didn't slip.. Drove great but as I put miles on it and the computer learns the tune it goes back to doing the same thing
Just talked to the guy who rebuilt the trans he saidI've been running into this here lately. New ECU's r fixing the problem.
Any help would be appreciated. Thanks josh
Just talked to the guy who rebuilt the trans he saidI've been running into this here lately. New ECU's r fixing the problem.
Any help would be appreciated. Thanks josh
04-29-2013, 10:10 PM
#2
If the pcm is learning the trans and making it slip thats a new one on me.... What do you have for power and what's done to the transmission other than just a regular rebuild? Something certainly isn't correct somewhere and I highly doubt its the pcm unless the tune is seriously messed up..
04-29-2013, 10:17 PM
#4
power range im probaly in the 430hp area not real sure on details on the rebuild, plus it never did this before the rebuild so i highly doubt it could be the pcm.. i just dont get how it acts peferectly fine after ive tried put a fresh tune on it then workes its way back to driving like crap ive done this a few times. i was out on the freeway the other day in drive and wouldnt rev past 3k i dropped it in overdrive and it had full power. gone threw all the plugs wires test the coils.. and its getting fuel..
04-29-2013, 10:41 PM
#6
Only thing that is weird to me is that it wont rev past 3000 rpm... If it was a transmission issue that was causing that (extra clutches applying at the wrong time etc) it wouldnt be long before it destroyed the transmission and you would know it. I use EFIlive to tune so I am totally no use to you on that end of it but I am pretty sure that Ted (Mrvedit) uses HPtuner and may be able to look at your tune for you and see if maybe there is something that you are possibly overlooking, its easy to do...
When you change the tune and "fix the issue" do you revert back to a previous tune or read/modify the current tune? Either way it probably doesnt matter because when you load a new tune it is going to start fresh on any learned behavior like transmission adaptives and fuel trims. I would tend to lean toward the fuel trims when looking for your problem but I am not in the car I am in front of a screen and keyboard so I cant feel it for myself either....
When you change the tune and "fix the issue" do you revert back to a previous tune or read/modify the current tune? Either way it probably doesnt matter because when you load a new tune it is going to start fresh on any learned behavior like transmission adaptives and fuel trims. I would tend to lean toward the fuel trims when looking for your problem but I am not in the car I am in front of a screen and keyboard so I cant feel it for myself either....
04-30-2013, 07:16 AM
#7
Moderator
Well, this sure is a strange one. As Carsonauto says the new tune is resetting the "learned" adjustments to the tune and it seems to be "learning" in the wrong direction.
The slipping is most likely due to low line pressure, which is controlled by the PCS (Pressure Control Solenoid, also called Force Motor), which in turn is controlled by the PCM. When the PCM detects more throttle or engine load, it increases the line pressure by reducing the current through the PCS. A bad TPS, MAP or MAF can confuse the PCM and make it command the wrong line pressure.
I highly suggest you hook up a pressure gauge to the trans (has a long 6ft hose), tie it to your outside mirror and drive it. It should be in the 175psi range under heavy throttle; I'll bet it goes down as your problem develops. A simple "fix" to try would be to just replace the PCS.
The max 3000 rpm is strange too, but I actually experienced it once or twice on the track. I wasn't exactly hot lapping, but on the 6th run in an hour, the engine would not rev past 3150 RPM; I took my foot off the throttle, tried again and nothing more. I actually have a log file of that run:
I shut the car off, checked for obvious problems and drove home with my fingers crossed. On the highway everything was again fine; it revved fine past 5000. I have no idea why, but the PCS detected something "wrong" and limited my RPMs to reduce potential damage. Not sure who knows all the "fail safe" programs running in the PCM. That was a '98 PCM. (I now run a '02)
So, I would start with the pressure gauge (which you can buy on Ebay for $45). I suspect once it starts slipping, the PCM is limiting your RPMs.
Ted.
The slipping is most likely due to low line pressure, which is controlled by the PCS (Pressure Control Solenoid, also called Force Motor), which in turn is controlled by the PCM. When the PCM detects more throttle or engine load, it increases the line pressure by reducing the current through the PCS. A bad TPS, MAP or MAF can confuse the PCM and make it command the wrong line pressure.
I highly suggest you hook up a pressure gauge to the trans (has a long 6ft hose), tie it to your outside mirror and drive it. It should be in the 175psi range under heavy throttle; I'll bet it goes down as your problem develops. A simple "fix" to try would be to just replace the PCS.
The max 3000 rpm is strange too, but I actually experienced it once or twice on the track. I wasn't exactly hot lapping, but on the 6th run in an hour, the engine would not rev past 3150 RPM; I took my foot off the throttle, tried again and nothing more. I actually have a log file of that run:
I shut the car off, checked for obvious problems and drove home with my fingers crossed. On the highway everything was again fine; it revved fine past 5000. I have no idea why, but the PCS detected something "wrong" and limited my RPMs to reduce potential damage. Not sure who knows all the "fail safe" programs running in the PCM. That was a '98 PCM. (I now run a '02)
So, I would start with the pressure gauge (which you can buy on Ebay for $45). I suspect once it starts slipping, the PCM is limiting your RPMs.
Ted.
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04-30-2013, 09:18 AM
#8
Ok thanks guys I tried unhooking the Maf and seems like the slipping gas gone away but still has the limiting rev problem all get my hands on a trans pressure gauge and see how that goes if in doubt all replace the PCM and hopefully solves my problem
04-30-2013, 10:13 AM
#9
Moderator
If you decide to buy your own gauge, search for "transmission pressure gauge ATD 5550" on ebay. Usually around $45 with shipping.
If disconnecting the MAF improved things, then it does sound like a sensor, tune or PCM problem. I assume the speedometer is reading correctly.
If disconnecting the MAF improved things, then it does sound like a sensor, tune or PCM problem. I assume the speedometer is reading correctly.
05-04-2013, 01:39 AM
#13
Tried my buddy's Maf on the camaro, acts alot better on low speeds and seemed to have good full throttle and no sliping but once I'm out on the freeway and go full throttle it hits 4000rpms and goes up in interval of 1000 rpms every few seconds then hits rev limiter and all back down off the throttle to let it shift
05-23-2013, 05:32 PM
#15
Moderator
05-25-2013, 06:43 PM
#16
cause i had a guy tune my trans with hp tuner. he drove around tuning it. he said it the downshift soilnoid cause when it has full power at launch but when your mid speed and want to hit the gas doesnt want to react so drop it down manual to previous gear and it goes.
05-25-2013, 08:32 PM
#17
Moderator
Read Page 30 of the 4L60E Technician's Guide? Here is an online version of the guide:
http://www.grail-ss.com/GRAIL%20Webs...ETechGuide.pdf
There is also a related 3-2 downshift valve and a 3-2 control valve, all working to prevent a flare or bind during the 3-2 downshift at different throttle levels. It really is "optional"; I have heard of some builders disabling it and in 2007 GM got rid of it by replacing it with "torque management" via the drive-by-wire throttle.
A problem in the valve body might be causing your problem, but I don't think it is one of the solenoids. Still, it is relatively inexpensive to replace all the solenoids and the PCS, under $100.
