CCDave

1987 4Runner 22RE Turbo with A340H from an 88 4Runner
During acceleration she's loosing power. For example, driving around town the RPM drops from 2,800 to 1,500 and slowly works her way back up to speed. Feels like she may be skipping 3rd and going right into O/D. This happens with the O/D on or off. With ECT Power on, it might be a little bit better, but not by much. The O/D light is not throwing a diagnostic code. After all I've done (list is below) I'm thinking the valve body may need servicing.

Watch the video (17 seconds) : "https://www.flickr.com/photos/davidjaeger/42859167764/in/album-72157675838247413/"

I've done the following tests, swaps, and replacements and there's been no change:

• Checked fluid level (both cold and hot), it's good
• New fuel pump and fuel filter
• Tested the throttle position sensor, it's good
• Tested for a clogged cat, it's good (used the fore and aft temp test)
• Tested for excessive exhaust back pressure, pressure is good.
• Serviced the transmission with a fluid drain, filter change (there were no magnets in the pan and the fluid was dark. This is when I started thinking maybe metal fibers have gotten into the valve body and it needs to be serviced)
• Replaced the 2 shift and 1 lockup solenoids (The old ones tested good, but had a new set so I replaced them)
• Tested the O/D main switch and O/D Off Indicator light, they are both good
• Completed the Manual shift test, it shifted fine
• Tested the coolant temp sensor, it's good
• Tested the speed sensor #2 and it's good
• Tested the ECT ECU - all volt measurements are good except the Trans Fluid Temp Sensor is reading 4.94v and it should be 12v according to the FSM. I tested the resistance on the temp sensor and that was good.
• Tried a different ECT ECU, same loss of power issue (and same 4.94v reading on the Trans Fluid Temp Sensor)
• Tested the resistance on the Neutral Start Switch, it's good
• Tested Stop Light Switch, it's good
• Checked throttle cable, it was not attached properly. Being that this tranny came from a different 4runner, the throttle cable is slightly longer and the lock nuts don't reach the bracket. I made a new bracket and played with various adjustments, but no change to the power loss issue.
• I was fortunate to get my hands on an ECT Analyzer (below) and ran that test. It shifted fine from 1-2, 2-3, but no shift change when switching the Analyzer to "4", which I believe should be O/D.
  
  What do you think, does it sound like the valve body may need serviced?

old87yota

I wish I was much more familiar with Toyota's Electronically Controlled Transmissions.

Is the loss of power you are talking about happening at about 8 seconds into your video?

Does the power loss definitely feel like the transmission is shifting into a higher gear rather than an engine power loss?

What happens if you get the 4Runner up to speed where the transmission would normally shift into Overdrive? Does the transmission shift into Overdrive? If so, when you turn the Overdrive switch off, does the transmission downshift into 3rd?

CCDave

Thank's for taking a stab at this. I wish I was more familiar with them myself.
Yes.

Yes. It does feel like a shift just before the RPM (power) drop.

I have never felt a noticeable shift into overdrive, with or without the overdrive switch On or Off.

Co_94_PU

iTrader: (-1)

I hear four shifts, is this what you experienced?
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Does it shift and drive "reasonably" when in the number two position with first second and third gear changes?

How reproducible is this?

The ECT computer will output it's current shift point as a voltage on the diagnostics line, you should monitor this and correlate it with what you hear and feel.

Seems to be running thru those gears fast. Digital speed is generated by the dash cluster. Maybe a loose wire giving false pulses. Maybe a voltage issue (dash lights not even, mine does this with bad power).

Pretty sure the temp sensor voltage is fine, I haven't crawled under and measured still but, they had several iterations it's either 5 or 12 a bad ones going to be zero or unregulated battery typically.

None of this precludes a valve body issue but before I did that I'd entertain some pretty ridiculous diagnostics.

CCDave