hardieca

I have fallen prey to they headgasket fix, yet still have code 52 problem. I have the old knock sensor and was looking to mock it up on the engine hanger to keep from having to tear off the top end again until I know for sure where my problem lies. I would hate to tear it down again and find out it was an issue somehwere else causing the code. I have read on here to use coax instead of a factory wire. How would I go about doing this?

Can anyone explain/ show how this fix works.

MudHippy

I'm not sure I follow ya there. Just how would that work exactly?

I can't tell you how to replace that wire with a piece of coax. I would imagine a little bit o' solder and a tad o' elbow grease oughta do.

I can tell you I also had the code 52 come up the last time I put my engine back together(8 months ago). So I can relate to that. Wasn't too much hassle to fix though. Aside from tearing nearly the entire upper engine back apart that is.

I got away with carefully cleaning the contact points on the sensor itself and inside the connectors/plugs at each end of that wire. They were way corroded(rusty) at the sensor end, but the wire tested good. So I figured a good cleaning was all that was needed. It was.

No code 52 since...

hardieca

Dang KS wire! Got new wire and new sensor. Hooked up and screwed new sensor to engine hanger. No more code. Thanks YOTATECH!

shaeff

The knock sensor is a closed circuit. By that, I mean that if you have a code 52, the ONLY possible issues are:

Bad wiring (most likely the case)
Bad KS (grab one from a junker, they're everywhere)
Bad ECU

Code 52 is just an electrical problem. It's basically what happens when the ECU doesn't receive a signal from the knock sensor, it retards the timing and enriches fuel mixture in an effort to prevent detonation/pre-ignition. It has NOTHING at all to do with actual engine knock, rodknock, etc...

If you rodknock your motor, you will not get code 52. If you run lean and detonate, you will not get code 52.

HeavyD

Add me to the list of code 52 frustration. I have a 1990 4Runner with a newly rebuilt motor and it runs very smooth and quiet, but is a dog on power with the code 52 error coming on. I had most everything replaced including the sensor and wire lead to the harness. I have researched this a lot, and I am down to the wiring harness to the ECU, the ECU itself, or the distributor. The distributor seams in good shape and I can set timing and watch timing advance as I rev it up, as it should. I cleaned the contacts on the wire harness connector for the KS and the harness itself looks good, so I am leaning toward the ECU.

The code 52 in the book states it is an "open circuit in knock sensor signal", with the trouble areas being "knock sensor, knock sensor circuit, or ECU". The book also states when the check engine light comes on, the motor will go into safe mode, which will kill the power to protect the motor. Although I could not see the difference in the timing after the light comes on.

My code also does not come on until I get RPMs above 2000 or start driving it. My last test was to unplug the KS from the harness, thinking the computer should pick this up immediately, but it was exactly the same as before. This leads me to think the ECU isn't reading correctly. Does anyone know if an ECU should immediately detect if a sensor is not plugged in?

shaeff

It's not your distributor.

If you unplug the KS, the ECU will react immediately and retard the timing, and enrich fuel mixture to prevent detonation. (That's the "safe mode" you're talking about) Retarded timing + extra fuel = no power.

sethb

The Code 52 also only comes up once you hit about 1600 rpm, I just fixed mine a couple weeks a go and every morning when I started her up, no CEL but once I actually started driving that sucker would pop on.

HeavyD

Exactly, the code does not come on until 1600 rpm. I just thought the code would come on immediately upon start up with the sensor disconnected, but it acted just like before waiting until 1600, which may just be the way it works.

Shaeff, the code 52 is a short in the circuit, so are you sure the ECU should show this code before the 1600 with the sensor disconnected? I will buy an ECU if I can prove it is the problem, but I am sick of throwing parts and money at it without the proof.

HeavyD

sethb, how did you fix yours?