admiralnahohkta

I read and read all the threads on this forum and others about Code 52. I feel I understand it cause and the fix(s). Having said that, I've done all I can and it still pops up. Anyone see if missed something:

1994 4Runner, 3.0l 4x4 M/T
1) Code 52 throws at more that 2000 rpm
2) Idles smooth prior to throwing code.
3) Wired new shielded wires (to E7 -5- terminal on ECU) and ground to engine bracket as describe in other threads.
4) Tried two new knock sensors (although neither were genuine Toyota parts).
5) Wired new knock sensor directly to ECU wiring to test. Still threw Code 52.

What's left that I missed?

Greatbert

I hate to say it but you could replace the ECM. what's the price at a junkyard?

RJR

Re: The ECM, there are a couple of threads on this board suggesting good results by replacing the capacitors in the knock sensor input circuit on the ECM board. I'd search for "ECM capacitors :f116" using Google. Apparently the capacitors can go bad and prevent the ECM from receiving a full strength signal from the knock sensor, thus triggering code 52 regardless of the health of the wiring and/or sensor.

The theory makes sense, but I have no direct experience with it. If you're comfortable with soldering on PC boards, it would be worth investigating.

admiralnahohkta

RJR, That might be a bit more than I'd want to take on, especially since a used ECM is only about $75. Then again, what do I have to lose, and it is a pretty simple board.

I feel like if the computer is so problematic as to have issues with voltage sensing it's amazing more of these don't fail. Let me chase down that capacitor thread....

Fermin4

After lots of tribulations I changed the ECU and the car is running much better. with no more CEL codes.

Also I could not figure out how to adjust the kickdown so when the gas pedal is depress hard and the car do not have the power in Drive, kicks down to second gear.
I try with the cable near the accelerator shortening end extended but not results.
Any help appreciated.
As a separate note, I took some waveforms with the PicoScope fo



r the two O2 sensors at the DLC and got something that probably still controlling the fuel/air mix but does not resemble any waveform that I have seeng for O2 sensors.
Files attached.
Any comments?

scope103

First, there is no "kickdown" cable. The transmission throttle cable that you were adjusting controls how hard the transmission shifts, but not what gear. Here's how to adjust that cable: http://web.archive.org/web/201408160...32prelimin.pdf

The OX2 signal is from the downstream O2 sensor. The purpose of that sensor is to monitor the performance of the catalytic converter. (If the downstream sensor swings in time with the upstream sensor, the catalytic converter is not working.) What were you expecting to find? The signal you give for OX1 (upstream sensor) shows the swing (from one side of 0.5 volts to the other) about 8 times in 10 seconds, which is normal.