RPM Spikes?

[petersondm1]

I'm hoping someone can help me. My 2002 TB started having RPM spikes 4500-5000 and would get stuck at that level. I couldn't hit the gas to accelerate further but it didn't lose or surge in power and I was able to decelerate to a full stop to get the RPM to go back down. This started happening in the 20-25 mph range first, stop and go, parking lots etc. No codes whatsoever.
Changed tranny fluid/filter/gasket Ran fine around town, getting it to 55, no problem. Got on the FW, hit 65, RPM shot up got stuck again and limped home keeping it under 40mph every time it spiked had to pull over. This time it threw a Torque Converter Clutch Solenoid stock open or failed code. Replaced that.
Checked the throttle body, looked like it had been cleaned recently (bought the truck around 6 months ago) and thought they may have damaged it so I replaced that while gasket was curing. (disconnected battery while doing this)
Another code came up for #5 coil pack so I replaced that along with all spark plugs.
Did the relearn sequence.
Now, sounds better than when we got it, runs smooth but the RPM spikes still spikes. The difference is that I can still accelerate and I can feel the gear change (no thumping, rocking or grinding). If I'm doing 55 it'll shoot up to 4000 and stay there for a few seconds before wiggling and coming down.
When this happens there is no spinning in sand sensation, no grinding/thumping and when we dropped the tranny pan there were no shards.

I'm at a loss as to where to look and any advice would be appreciated. Thank you!

 

[TJBaker57]

Would you happen to have an ELM327 OBD adapter?

 

[petersondm1]

No I don't. I took it to Autozone up the street when it finally threw a code the other day

 

[budwich]

its unclear... are you saying that you hear your engine rev that high or that you are watching your gages and they are "popping"? you would be wise to get some form of data monitor to look at a few things instead of relying on just reading codes "post fact". At 4000-5000 rpm, I would think that the vehicle would try to down shift in the form of passing gearing request.

 

[petersondm1]

When the gage spikes we can hear and feel the engine rev but it doesn't affect the current speed. I just took it out again and if I take my foot off the gas it'll go down now and I'll hit the gas again to accelerate but it'll happen again after a few seconds. It seems to be happening when I'm maintaing a speed (?)

I've also just put Seafoam in and am getting ready to use the other seafoam through the air intake

Thank you!

 

[budwich]

:-( I think you have tranny issues as any "real rev" will head thru the tranny.... maybe.
does the shift indicator on the dash change during the event?

 

[petersondm1]

:-( I think you have tranny issues as any "real rev" will head thru the tranny.... maybe.
does the shift indicator on the dash change during the event?

This is an automatic, sorry I should have mentioned that so no shift indicator. It happens at low speeds 20-25mph or at high speeds 50-55mph which is why I'm hoping it's not a tranny issue because it's not at one particular gear.
We just put the Sea Foam (big white can) into the gas tank which was just under half full and sprayed the Sea Foam intake cleaner, let it sit for 10 min, drove for 10 min. That produced a LOT of white discharge from the tail pipe. But, the spike still happened on the drive.
A week ago we had no control, it spiked and we had to pull over to get it down basically limping it home. Now, when it spikes we can let of the gas and it'll come down but it wants to sit at 3500-4000 while trying to maintain around 55mph

 

[TJBaker57]

The reason I asked about the OBD adapter is I recently have been working on a display that shows the transmission gear ratios. If one looks up the 4l60e ratios for 1st, 2nd, 3rd, and 4th you will know when your trans is slipping. I have been watching the ratios on a graph where a slip is very quickly apparent.

 

[budwich]

it would be hard to believe that rpm's can "double" without noticeable "thrust" so it is likely that either there is significant "slip" or a potential momentarily "shift" happening in the drive train. As mentioned, a data monitoring device (app plus obd adapter) can be setup to give you a view of what the PCM is seeing at the time of the incident. You can go from the results. I personally monitor gearing and "slips" all the time when towing. My understanding is that the "slip management" for torque control is "quite dynamic" but I don't know the inner "working" but feel that this would be the likely area of interest.

One other thing... you mention there is no shift indicator????? what you mean, there is an indication on the instrument panel which gear the car "thinks" it is in. That indicator is NOT mechanical, it is set by the system and can change without you physically moving the shifter IF the system has a false reading to do a change. That was what I was asking about.... was that instrument panel indicator changing?

 

[gmcman]

Almost sounds like you are toasting your trans. What does the trans fluid look like?

I wouldn't drive it anymore until you figure out what's going on. If you have a pressure issue somewhere only bad things are going to happen. Could be an accumulator piston, separator plate, piston seal, hard to say, may not be a pressure issue.

Since you are losing power to the wheels, it sure looks like the clutches are possibly slipping or not engaging.

 

[TJBaker57]

Having burned up a couple of 4l60e I noticed that the built-in codes don't seem to show until the damage has been done. The only slip live data I could find was for the torque converter. I wanted more. We have data for transmission input shaft speed and transmission output shaft speed. I made a virtual pid in torque where I divide input shaft rpm by output shaft rpm and voila! Gear ratio downstream of the torque converter. Display in a graph and any slip is readily apparent. Also display your current gear and maybe the shift solenoid positions and I see a pretty good look at the trans.

 

[TJBaker57]

Here is a look at what I'm talking about. The graph and the value in the center display are the same, just represented differently, graph vs value. Top left is Torque Converter slip RPM.

 

[Mooseman]

I agree with everybody. Sounds like the tranny is slipping if RPM's are increasing but the the speed isn't affected. You changed your filter and fluid. What did it look like before the change? Have you tried manually shifting it? What does it do going through the gears?

Even if the TCC is slipping, there wouldn't be a wild RPM inclrease and the tranny would still accelerate the truck.