I ve been looking through the threads for an hr now and searching and have found nothing. Okay the problem Im having is when I go WOT at an time the car starts pulling hard and it is like the RPMs will quit going up then I hit the REV limiter and the minute I pull out the throttle and lightly get back on the throttle it shifts and this is for every gear!!!!!! its killing me that I cant drive my car to its full potential and Im worried about my poor baby. If Im driving it normal it shifts just fine no problems. What would cause this? Please I know youre going to have ppl saying read other threads but all the other threads I ve came across are for built transmissionn with Stalls mine is a Stock 4l60e with stock stall and 118000 miles on it. I just want some input before I spend 1500 on a performance transmission, 500 on a stall and 550 for labor to get it installed bc Im a recruiter and dont have time for this ****!! So any advice would be a great help. Thanks!

 

mine is doing the same thing on the 2-3 shift, i brought down the shift points which kinds helps mask the problem and it shifts now, just not like i know it should, i have heard that this can be caused by the clutches going out, not verified yet though

 

Check to make sure you are getting the full RPM from you engine first. The transmission shifts off of engine RPM at WOT. If it does not see the calibrated RPM per gear it will not shift . Check for codes if possible also.

 

I know with mine it is actually seeing the right rpm, my datalogs show no codes and show the shift being commanded at 5100 (where i have it set now) but actually carrying up to 5950-6000 before making the shift, any idea why TPT

https://ls1tech.com/forums/automatic...oint-down.html

Thanks

 

My car isnt throwin any codes and I used to have 3.73 gears and my old aluminum drive shaft but I broke the gears and cracked drive shaft. I wonder if that had anything to do with it. But could my clutch disc being going out in my trane or could the pump be going put bc I know the ECU controls the Line pressure bc when you go WOT the ecu turns the line pressure up by the transmission pump and if the pump is starting to go out that would mine the line pressure is staying the same. If Im wrong call me on it. LOL! I only know basic motor stuff not much about transmissions or eletric stuff.

 

So do you still have 3.73 gears? If you changed gears with out a calibration update, you would have that problem. It could be clutches or even a bad pump. I was trying to be optimistic. Low line pressure will usually cause a long slipping shift in all gears.

 

I'm having a similar problem as evilbeef with the 2-3. Has only happened at the track on drag radials. I don't think I have it set all the way down to 5100 though, I'll have to check what it is. Only hit the limiter a few times than shifted. Don't think I let off.

If it is the clutches or pump, is that stuff repairable, or should you just get a new built tranny?

 

Does anyone have anymore input on this. I need as much as I can get bc before I go and spend 2100 dollars and my wife kill me I need to way my opinions.

 

So I understand you, you said the car will accelerate hard then the rpm's quit going up and you have to ease off the pedal to get the car to shift? Look at the fuel pressure, possible filter or pump. All of the trans is consistant with this problem. Also, there is more than one area to tune the trans and all must be on the same page or this problem can occur. The trans does not know what to do until it is programed to. Check the fuel first, lots of miles, then look at the trans tune, gear ratio, tire size, etc. If the clutches or pump fails, there will be alot of slipping, not pulling hard. Keep us posted.

 

I thought MPH played a part in WOT shifting... is this not true. It always seemed that way when changing set-ups at the track: n20, slicks. n/a, radials, gears. Seems you always have to correct shft points by taking/giving MPH.

 

at least for my problem it does pull nice and hard it just doesnt make the shift and bangs off the limiter untill i lift, once i brought the rpm shift point down to 5100 it finally makes the shift at 6000, the MPH is set at 35 so i know that isn't the issue. looking at my datalogs the shift is commanded at 5100 it just doesnt shift till 6k, both my tune and the one from pcm4less are doing this

 

Mine did this also last year at the track. I would come off the line and the car would bog on the 1-2 shift. I mad some adjustments with a hand held but it did not help. I manually shifted off a light all season and i ran fine. I am going to get the car up to the tuner New Era before the season starts to see if there that is causing this.

 

Bear in mind also that while the shift may be commanded at 5100 it could indeed take to 6200 for the trans to make the shift . You see while the electronics are instant hydraulics are not and several things come into play. One thing is a constant at WOT it always takes the same amount of time for the trans to complete the shift. This time will of course vary from trans to trans depending on condition, Shift kit set up. Line presure.

What does change is the rate the RPM are climbing under various conditions. These numbers are off but bear with me.
Lets say it takes 1 second to complete a shift from 1-2 and at 340 hp NA the RPM climb 300. Ok same time period at 600 hp the rpm might climb 600 RPM during the same period. Other variables would be for instance gear ratio and engine with 4.10 gears behind it is going to climb in RPM much faster that lets say a 3.23 would so then again you might have another 300 or more increase in the RPM during the same time frame between the two gears.I think this is why many times you hear of people boucing limiter after going to lower gears even though they did set up the PCM for the hear change. They failed to compensate for the RPM rate increase. With the stock converter and stock power the PCM can adapt but once you get outside those it cannot do so on its own. Add a shot and the RPM rate increases again even though the time for the trans to shift is still a constant.

I think this is why you hear so many people talk about bouncing the rev after mods they changed something wether it be power or gearing that changes the rate of the rise and fail to realize that all of these things have to be compensated for. Its not as simple as I want it to shift at 6000 rpm and set it that way because to acheive and actual shift at 6000 RPM where you would actually have to command the shift would be different for virtually any mods you make that can affect the rate the RPM rise during the shift.

So realistically every car would be different depending on the POWER/GEAR RATIO/SPRAY.
Then a converter with a high stall is still a further complication and the RPM due to the slip in the converter may be higher that expected for the MPH and this again would vary again with the addition of power adders such as Nitrous or even rear end would affect this too.

So the conclusion I have come to is there can be no one size fits all when it comes to tuning for shifts it would be unique to each set up. A car with 4.10 might take 500-800 or whatever to complete and shift and a 2.73 car might do it in 200-400 and power adders change these numbers around more. So its kinda a trial and error system I would conclude would have to be used.

Also you have to beware looking at the shift completion times with the 4l6x units since the PCM uses the engine rpm verse output speed to determine when the shift did happen and with a stall these numbers can be way off so are useless. The exception would be the late 4lxx with the input speed senor 07 up with these you would get a true time since the converter is not part of the equation.This would be true of the 4l80e also since it does have input speed sensor.
Ramble over lol

 

hmmm... okay good info, thanks, so what im gathering is there may not be a need to worry, just set the command for where it works? any additionalo tuning that should be done for a convertor

 

Yes thats the basics of it put it where it works . As for a converter you have to set the shift point to work with it of course and I like to see lockup only above 40 mph in 4th gear

 

okay cool thanks for the input