The switch I have been using is factory to the Malibu. It’s just that the switch is bad. I still have the switch from the donor 94 Z28. I plan to put that in.Originally Posted by tayto
The switch I have been using is factory to the Malibu. It’s just that the switch is bad. I still have the switch from the donor 94 Z28. I plan to put that in.
Don't think it affects the shifts, only the TCC unlocking.
THEY are NOT Lying to You.
You are NOT Even Lying to Yourself.
You ARE Being Lied to ... by Your SELF.
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You’re chosen connection has full time 12v to the TCC wire. My condition with failed switch has no power on that circuit. So, my situation is not comparable to yours since you’re feeding power where it’s needed. In my case, there’s no power on the required circuit.
should be throwing a code 38 if that's the case. FWIW, my 700r4 doesn't shift to 4th until 45 mph. in your datalog you should see if it's commanding shift solenoid A ON and B off @ 45mph (or whatever your shift table says), if it is and not shifting probably an internal problem with the trans.
Last edited by tayto; 08-17-2021 at 10:56 PM.
Thanks. I need to check the flags in the bin to see how they are set. The previous tuner turned some stuff off but I'm not sure exactly what was turned off or left on.
Worked on it a little this evening. I fixed the brake switch and now it has the signal it needs to allow converter lockup which I verified on a test drive.
I have not changed anything in the bin yet but I hooked up EEhack and noticed a code logged. 21 - throttle position high - cleared the code.
Also in EEhack I observed the TPS % readings with KOEO. It went up normally as the pedal was pushed from 0 to 100 but at 100, there was still a little bit of pedal movement available towards the floor. I continued to push it down and when totally floored, the TPS percentage suddenly drops to 4.3 %. That can be good can it?
Earlier in the project I had been chasing suspected vacuum leaks and I was fiddling with the throttle stop screw and TSP adjustment (slotted mount holes). What do you bet I need to revisit that throttle stop and TPS position adjustement?
Since discovering the TPS percentage drops to 4.3 % at WOT, I test drove limiting the throttle opening to about 50%. It drove and shifted great.
Btw, I understand that the brake pedal switch may only control unlocking of converter.
Speaking of lockup, under normal operation of the 1994 Z28 4L60e, does the converter only lock up in 4th, or does it also lock up in 2nd or 3rd?
Meanwhile, I’ll keep you posted when I get to sorting out the possible TPS issue. I’m fairly confident there’s not an internal transmission problem.
Under normal operation of any LT1 coupe, hatch, sedan, or wagon, the TCC can lock in 3rd or 4th.
Although we COULD command it to lockup in 2nd, even if the correct 'TCC Lock' & 'TCC Unlock' values are used (and I personally do NOT believe in PWM of the TCC, I only use '94 values), locking it in 2nd is just not worth it under most circumstances. GM did not lock the TCC in 2nd.
Preaching to the choir, but … GM rushed to upshift to 4th ASAP to appease unrealistic CAFE MpG tests.
At boring TPS% & decidedly boring road speeds where MpGs are a major goal, 3rd&Locked is almost always better than 4th&Unlocked for the 4L60E - with <3.73 axle.
It may feel a bit odd until you calibrate the TCC Lock & Unlock road speeds to your foot & taste.
Once you've readjusted the physical throttle body properly, your TPS percentages - or are those Voltages? - should behave properly.
THEY are NOT Lying to You.
You are NOT Even Lying to Yourself.
You ARE Being Lied to ... by Your SELF.
The Last Psychiatrist, aka ... Alone ...
3rd or 4th, got it.
Those numbers I reported are throttle opening percentages. I plan to investigate the voltage values as well.
my current non-ecu controlled lockup is useless until about 100kph. Shifts into 4th and immediately locks up. I've been driving around in D until I swap in TBI harness and/or re-gear (currently 3.42s, want 4.11s or 4.56s). I will be keeping Qjet for now and have ECU control timing and lockup.
Here’s the problem verified. TPS voltage is going too high. From what I understand, anything 4.75 or above is faulty.
https://youtu.be/TTDZzB9DbE0
It went like this. Start up and drive off. Transmission works normal and shifts on time until you open the throttle fully and it gets the fault of high tps voltage. From that point on it will shift late and skip 3rd and go right to 4th. Pull over, turn the engine off. Start it up and drive off it will be shifting normally again. Go full throttle even one time and its back to qwerky behavior again.
I'll be able to get the TPS adjustment correct no problem. I just wanted to share the symptoms and how I can duplicate them.
Got the tps adjusted and shifting is good now. No excessive delay in part throttle up shifting, good kick down response, converter locks up when is should. Speedometer scaler verified as good compared to gps. One thing I’d like to change is the WOT up shift rpm. Right now it revs strong to about 6100 and hangs there fir a second before it shifts. The slight delay seems like a waste. I’d like to get it completing the WOT up shifting by 5800. This adjustment will be a new one on me as I’m learning as I go. Where in the TunerPro can I lower the WOT up shifting?
Thanks, I’m learning more from your help
my current bin is attached
Last edited by JD1964; 08-22-2021 at 04:30 AM.
The table you're looking for is in Automatic Transmission -> Kickdown Mode. There are three tables you need to focus on. They are:
Kickdown Mode Enable TPS Threshold: This is the minimum TPS% required to enter Kickdown (WOT) mode. Your car is currently set to 94.53% TPS. That should be fine.
Kickdown Normal Mode Shift RPM Thresholds: This is the minimum RPM that must be reached before Kickdown Mode will allow a shift. This is only half of the equation, though; the other half is the table below. Both criteria must be met for a shift to occur.
Kickdown Mode Up/Down Shift Points: This is the minimum VSS speed reading that must be reached before Kickdown Mode will allow each shift. As above, these are used in conjunction with the RPM table and both must be true for the shift to occur.
Right now, if you have stock 4L60E gearing, a 26.0" tire, and a 3.73 rear ratio, then here are the RPMs that your car will actually shift at based on the BIN you just attached in your post:
1->2: 5450 RPM (RPM table limited)
2->3: 5450 RPM (RPM table limited)
3->4: 5400 RPM (RPM table limited)
Your speed tables all clear before the RPM does (1st gear is RPM-limited-only by default, 2nd gear 67 MPH is 5265 RPM, 3rd gear 111 MPH is 5351 RPM), which means the PCM is only looking at the RPM limit at that point (5450 RPM for the 2nd and 3rd gear shifts, 5400 to the 4th gear shift). If your transmission is hanging at 6100 RPM before shifting, then you have a few possible problems and it's up to you to find out which they are.
First, are you sure it's 6100? Is that what EEHack is actually reading? The tach on the dash tends to be notorious for reading high, while EEHack will show you the actual distributor pulse RPM.
If it really is 6100 RPM, that means your transmission is attempting to shift at 5450 but is not able to complete the shift in time. Could be a bunch of reasons why that would be the case. You can try lowering both the speed values and RPM values to see if that'll get the shift down where you want it, but chances are it won't change the "hanging" sensation, it'll just lower where in the RPM band it happens. Chances are the "hanging" is gonna be something with your transmission. Might want more line pressure, might be worn out and want new clutches, something mechanical like that. I'm not a transmission expert so I'm afraid I can't really help you diagnose the hang if it really is doing that.
But as far as lowering the shift points at WOT, there ya go.
kickdown.jpg
1990 Corvette (Manual)
1994 Corvette (Automatic)
1995 Corvette (Manual)
Thanks for that input NomakeWan,
The datalog shows the PCM commanding the shift according to the tables in the bin at 5450rpm. However, the shift is not completed until 6100. There is no slipping whatsoever in the climb through the powerband and when the shift happens, its solid with no apparent slippage or slush. It's obviously being delayed within the transmission but when it does happen, it feels healthy. So, I don't think I have any clutch slippage issues.
The story on this donor car (94 Z28) is the mother let the kid drive it and he put it in a ditch causing moderate damage to the right front corner. Thats what took the car off the road. The car sat for several years after that. When I bought the car they claimed the transmission had been rebuilt a few months before the kid wrecked it. When I pulled the engine / trans from the car I found initials and date written on the bellhousing with sharpie marker. The data coincides with the time the trans was claimed to be rebuilt. She said she knew the mechanic and he was familiar with the weakness of these transmissions and he had done stuff to improve it. She did not know exactly what so neither do I. Not to ramble but this may support my position that the transmission should be healthy internally.
I did some research and found this thread which further helps me understand things. Look at line 5 about shift timing. I think Ill try adjusting the the max MPH lower to see if that gets me where I want.
http://www.gearhead-efi.com/Fuel-Inj...vations-(8051)
Also, further down in that post look at line 3 in the tuning suggestions. I compared those suggestions with my bin and I think I found another potential issue with my bin. I posted the table below. The tuner (who I'm sorry I paid) has errors there too I think. In the 2-3 shift timing its set to 6.38 seconds. Shouldnt that be .638 sec instaed?
shift-time.png
Last edited by JD1964; 08-22-2021 at 04:26 PM.
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