SMKE EM

iTrader: (2)

I'm very confused right now.

I have HPTuners but I didn't have time to log this yet (I will tomorrow)
However, when I bought my TBSS it was snowing, rwd everything seemed fine.

When it got warmer out and roads were better I had a hard shifting, delayed shifting problem with no codes just intermittently. I ended up getting a MAF code after a week and a bank 2 lean code.

Switched MAF and it was snowing today but it seemed like the shifting was MUCH smoother.

However the main problem that existed before, and even now is at WOT at say 50-60mph, RPMs jump to like 5k, and car goes nowhere. Speed doesn't increase, my rpms don't increase but very slowly almost like there's a speed limiter or something on my truck. I am afraid to hold it anymore than 2seconds because I don't want to damage the trans if it does decide to shift hard.

Has anyone every experienced this before? The PO claimed to have put a new transmission in from the dealer (and it does look new under the car) but the guy lost the receipt or some **** so it's kind of sketch.

Help!

mrvedit

If this only happens during the 2-3 shift it could be a worn 3/4 clutch, the most common problem with these transmissions.
If it also happens with the 1-2 shift, it could be a bad forward sprag, another common problem.

Since you have HPTuners, also log Transmission -> Force Motor (PCS) Line Pressure.
We want to be sure the PCM is commanding max line pressure during WOT shifts.

SMKE EM

iTrader: (2)

It looks like a brand new transmission, if it shifts and drives like butter at all other times, could it still be the clutches or sprag?

From a stop I tried WOT from a stop and it did the same thing I think it was 2nd gear

SMKE EM

iTrader: (2)

I also verified I am getting full TCC engagement and I have minimal RPM slip

Here's a log before I changed the MAF on my way to work one day

SMKE EM

iTrader: (2)

Here's a log with lots of WOT

Circle-D_Brian

The nice thing about the 4l70 is the input and output speed sensor. You should be able to see easily if you have trans slip.

-Brian

SMKE EM

iTrader: (2)

Ok I added PCS Input and Output....guessing I found my problem today. I think the WOT runs burned up my clutches or something because the vehicle started struggling later on getting home.

Can someone view this log and tell me if I am right here and what the potential causes may be?

Thank you

mrvedit

Looking at your log, I see that "Force motor (pcs) duty cycle" stays at a steady low 27.8%. Honestly I have never logged it myself, but I expected it to increase under load. Perhaps I am mistaken there and force motor (pcs) actual current" would have been the right thing to log. (I put a trans pressure gauge on to read actual values and don't log these myself.)
If true, the PCM is commanding low line pressure causing your trans to slip.
I don't know what "Absolute Load" is, but it stays at 42 as does "Desired Trans Torque".

Not related to your trans problem, but your wideband stays at 12.80 or 12.81 even though the commanded A/F is changing, the O2 sensor voltage is changing the short and long term trims are showing huge errors.

If not too much trouble perhaps you could log the other Trans -> Force motor parameters to be sure we are looking at the correct one(s).
Also, can you post your tune?

SMKE EM

iTrader: (2)

Not sure why my MAF code keeps appearing I have a known good maf installed.

The trans is getting worse, it struggles to accelerate at highway speeds now

I noticed the PCS valve WAS working in the beginning, but as I drove more it was producing 0.0A and duty cycle flatlined again.

mrvedit

I don't have HPT installed on my office computer to check your file, but will tonight at home.
However, 0.0Amp to the PCS gives it max pressure (opposite of what you might think.)

SMKE EM

iTrader: (2)

Ok, then it must be slipping because at cruising speed 60mph I don't think it should be at max line pressure.

Here's the tune file for truck, just pulled it. Let me know if anyone sees anything irregular. I have a stage 1 4L70E on order from SRT in Kankakee, IL, hopefully my trans wont go before then because it was bucking at 60-65mph and had a hard time accelerating.

mrvedit

Yes, at the beginning the PCS current was changing and the PCS duty cycle was changing with it as I would expect. The Absolute Load was changing too. During this time the "Trans Pressure Mode" was set to "Steady".

However later the "Trans Pressure Mode" changed to "Diag Max" and the PCS current changed to 0.0 Amp, the value for maximum pressure. I sure don't know this for a fact, but I postulate that the PCM detected a problem (slippage?) and switched the trans to "Diag Max" mode and set the maximum line pressure to try and preserve the trans.

mrvedit

On a quick examination your tune looks very normal to me. The PCS tables are all fine.

Note that the "Pressure" listed in the PCS tune tables and in the log file is NOT the line pressure. It is a control line pressure between 0 and 95psi which moves the boost valve which in turn changes the actual line pressure, typically between 50 and 200psi.

SMKE EM

iTrader: (2)

Put new level 1 trans in yesterday, same thing is happening. HELP

I a have MAF code and bank 2 lean code, but I had those before so I switched the MAF with a known good one, the intake manifold gasket, cleaned all surfaced and torqued to spec. Still didn't fix that problem. Does anyone have any idea wth is going on?

mrvedit

Buy a trans pressure gauge "ATD-5550" on Amazon for $34 and hook it up. It has a long hose so that you can even monitor pressure while driving with the gauge hooked to your mirror.
However, stationary test are often enough to detect a problem. Post the pressure in Park, in Reverse and in Drive. With the trans in Park, blip the throttle and see how high the pressure goes.

I now wonder if your trans will fail the "blip the throttle" test. I now suspect that the PCM or engine sensors are defective, resulting in low line pressure and slippage.

Obviously unrealistic, but if everyone bought and connected a pressure gauge to their trans before they posted a new problem thread, most of these threads would be half as long and the OPs would save a lot of time and often money. I'm sorry I didn't suggest this in my first post here, I do in many other threads.

SMKE EM

iTrader: (2)

What pressures should I be seeing?

mrvedit

Without a shift kit, pressures are typically:
Park: 50-70psi
Reverse: 150psi
Drive: 5-70psi
Blip throttle: 150-200psi

With a shift kit and/or bigger boost valve, values are typically 20psi higher.