Son has a 1990 6cyl 4RUNNER that I have been slowly bringing back up to good running cond. Has had the engine replaced with one that had approx 100k miles, new heads/gaskets from the previous owner. The truck runs well, no knocking which was a prior cel code for the knock sensor. Now the problem is on acceleration, the cel will come on and stay on as long as is running. Once shut off and restarted is off until starting off again. here is the problem, I can't get the trouble code off the computer. It does not show up when I ck? Any insights into this cel? Milage is about 13-14 city. I'd appreciate any input into what can be up?
BJ

 

have you tried pulling the EFI fuse in the engine fuse box? Take that out for 10 mins or so and all the codes will be deleted. If it comes back after that you have a problem with the sensor or the wiring.

P.S. the wire is what usually fails, as a result of the heat it is exposed to as it is under the intake and between the heads. Mine was so bad the rubber surrounds on the wire cracked off like hard plastic. So it maybe the sensor or wire going bad not the sensor actually trying to tell you you are knocking. Was the sensor replaced during the rebuild? if not it is probably bad and needs to be replaced.

 

Anytime I do a rebuild on one of those, I recommend replacing the sensor as well. Ive done a couple where I have recommended it and they didnt want it. After it was all back together and running, they had knock sensor codes so I got to pull it apart again to fix it. If you do indeed have a code 52, replace the sensor and the wire.

 

After reading the post which I'm grateful for, indeed the code 52 came up again. It does not knock! So the former owner probably did as ToyTech said and to not replace it. What is involved in replacing it? I've had the whole front off replacing the radiator, upper idler bearing, fan bracket, I'm just wondering if I have to take the plenum off? I'm kind of tired of working on this truck. Can you tell me where the ecu is and what wire is the KS to it. I think I'm just going to mount one to the firewall grounding it out with a new wire to the ecu. Is my solution viable? Runs fine but does kick into default retard mode and that is why the mileage is crap. I have not searched for the instructions on KS replacement but would appreciate a link if you all know.

BJ

 

By no means should you bypass the knock sensor. IMO its a halfass repair and shouldnt be done. Damage can be done to your engine by doing this. You dont need to hear the engine knocking for it to work/not work. The sensor itself is in the valley of the engine. You need to remove the plenum, intake manifold ect to get to it. If you lived in n cali I could do it for you.

 

Ok, well you sold me here, not to go the 1/2 arse way. I do not look forward to the repair! Until I get the part and wire, I am going to advance the ig timing for it is a dog. Hopefully this will not be negated by the computer.
Bryan

 

Well, came back from a wet Texas coast vacation with the kids to work on the sons '90 yota 4runner 6cyl. Knock sensor is in stock so I started work today on it and found that the transplanted engine/6cyl engine harness had been messed with at the knock sensor connection. I found what looked like coax coming out of the harness and a plastic connector going under the intake plenum.
Arse h who did this must of did not want to make purchase the appropriate knock sensor and took off the engine harness's plastic connector! I did a clean up and got the wires cleaned, cut off any dead looking and now I need to know from a Yota tech techs, what do I test on the leads from the harness to know it is "LIVE". Ohm readings with engine on? Volt readings???

Thanks again for much help in the past.

BMJ

1990 4x4 4runner 6cyl
1998 4x4 4Runner 6 cyl Supercharged

 

I need the same information...what's running through those wires?

I just replaced an engine on a '95 4Runner. Also replaced the wire, but NOT the sensor. I also get a code 52.

I just want to double check the harness before I tear down the engine AGAIN.

BMJ, if I find this info elsewhere I'll be sure and post it here.

Mike