CpMike

Well judging from the posts I've read, Engine code 52 is a big issue with the 3.0 engine. I had no problem such as this until after my rebuild. I replaced the Knock sensor and intake pigtail when I was putting the engine together. I've checked the harness for continuity and for shorts and it appears to be OK. This has been a frustrating problem as I have only used the Runner for short trips until I can solve this problem.

Adding to this frustration is an additional problem that appears to be ECU or power supply related that I have had since before the engine was done. The CEL comes on for the code 52 at the typical time with RPM over 1600 and stays on, but every once and a while the engine seems to die for a split second and the truck jerks and the CEL turns off but comes back on as soon as the rpm is over 1600 again.

I've put a lot of time, money and effort getting my runner looking respectable again and I am getting discouraged with this issue. If you have had this experience & have solved these issues, please help me to get my runner running the way it should.

olharleyman

02 sensor iirc

lilevo

I just had this issue today. It's been very cold out and when first starting the truck in the morning, I had a CEL. I pulled a code 52 which looks to be the knock sensor circuit.

However, if I turn the truck off, then turn it back on again, the code is gone indefinitely and the truck runs fine.

I replaced the pigtail but not the sensor when doing the head gaskets.

I'll keep you posted. I'm not sure why it's fine after I shut the truck off and turn it back on again.

westernbound

CPmike, I have the same problem,did you ever fix it and if so how?

westernbound

I feel ya,Ive got about 4 grand in mine and the only problem left is that f****ing code 52 and power loss.I put a new distributor and wires on and it helped for a bit but its back to its old ways,damn it its going to the stealership I reckon..

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?

westernbound

find a knock sensor,drill a hole threw the engine hook same diameter as the threads on sensor slide sensor in attach nut to the threads..puchase another pigtail harness,hook it to the wire harness attacment and then to the other knock sensor...problem solved

CpMike

Hey Westernbound! Thanks for your post but I'm a bit confused with your wording. Could you spell it out a little more clearly for me. Has it fixed your problem? I've been restricted to 5000 KMs in 2 years with this problem and have just lived with it.

westernbound

1.detach engine lift hook,the one on drivers side near the fire wall 2.Drill a hole half way up your engine lift hook the diameter of the threads on spare knock sensor 3.slide sensor(threads) into hole and attach a nut that will work on the threads and tightn it.4.reattach lift hook knock sensor facn out.5.detach pig tail harness on existing sensor and leave it in place,take another pigtail harness and attach it back into connector on main wiring harness and connect it to knock sensor on engine hook..done.doing it like this saves you the time of takn off the plenum and intake manifold all you need to do is gett to the harness contection inbetween injectors and air intake at the plenum(shold be green plastic connector)might have to take air intake pipes of from mass air meter to plenum to get to everything better..there are detailed instrucctions floating around these forums with pics..mine running normal now so....good luck

Ricky B

I hate to wake up the dead, but this looks like the magic solution to our own problem on the '91. One question though, could someone please explain to me exactly what Safe Mode is, and what it does? And would it have any effect on the tranny going into/popping out of overdrive?

Thanx in advance....

CpMike

Just a follow up on my problem and it's solution. I did the remote mount for the knock sensor and that allowed me to easily verify the circuit's integrity. On that note, anyone who takes that circuit apart, thoroughly clean terminals and use a conductive electrical joint compound to ensure a very good connection and always replace the short intake wire. This clears my code 52 problem.

The check engine light cleared but I was still having the "jerk". Cleaning all the engine harness grounds and using the same conductive electrical joint compound corrected that problem. Loss of current flow to ECM.

Finally, the big fix! The poor idle, high fuel consumption and low power issue was caused by the aftermarket cams. The Topline brand cams that I used were defective as far as the valve and distributed timing. After swapping them out with melling camshafts and installing the knock sensor back in the gallery the truck runs great and has good power and good fuel economy. Well at least as far as the 3vze is concerned.

akukeval

I just had the heads done on my 91 4Runner and now I am getting a Code 52 and I was told that I can remotely mount a Knock Sensor with a Pigtail Extension, Where can I mount this Knock Sensor, Any Ideas,
Please let me know asap
akukeval@yahoo.com
Thanks Guys

CpMike

There are threads with pictures on the subject of remote mounting your knock sensor. It is a temporary fix, the 3vze is bad for pinging and the knock sensor helps the ecu adjust the ignition timing to prevent it. If the knock sensor is not picking up the knocking or pinging damage to valves and pistons. That being said, the left engine lifting hook can be drilled and tapped to accept the knock sensor and is close enough to the main engine harness to make connection easy. However I can't stress the cleaning of the contacts and terminals of the sensor, pigtail and main harness is important. And use a electrical connection compound on all connections is critical. The ac signal from the knock sensor is very weak and is very susceptible to electrical noise. Excellent connections are critical.
Hope that helps. I know this engine can be frustrating.
Mike

Team420

I would avoid the remote locating of the sensor! as stated above, these motors ping, and the KS is there to help that. Putting the ks somewhere it wasnt designed to be, may make the light go out, and may restore some power, but could/will lead to adverse affects later down the road.

Honestly.... grab a 12 pack, and start tearing into it! It's not that bad... and while in there, ya can seal up any vacuum leaks that might occur around the intake gasket (these leaks are extremely difficult to find with the motor together and running), also replace the valve cover gaskets, unless this was done recently, they most likely leak(also a vacuum leak) or will in the very near future.

I also had to go a step farther on mine, the connection from the pigtail to ecu had a short in it, and I ended up re-wiring the KS all the way to the ecu.

Its not too bad a job, but is certainly time consuming (plan on 6-8 hrs to be safe), So do it right the 1st time, and never worry about it again.

Good luck!!

mxoliver115

I've been planning on rewiring my knock sensor but I want to do it right. Could you walk me through it from the ecm to the sensor. My wire shows continuity but I'm not trusting my splices and the old wire.

mdyoung

I am having the same issue with my 89 4runner. I will be replacing the KS. I want to replace the harness at the same time. Is there one out there someone could recommend?

Thanks!

mxoliver115

No one seems Post fixes but asks a lot of advice . here's what I did. I looked for a harness for my 88 runner. They are like 250 bux . I couldn't an aftermarket harness. I went to radio shack and bought a rg85 cb antenna coax. Soldered it to the sensor and to the wire that comes out of the ecm right where the ground wire is. Next I'll be ordering new injector connectors so everything on mine will be good . code 52 gone. For some wiring and a 12$ coax

mdyoung

Thanks! I just found an OEM knock sensor harness on ebay for $11.48 http://www.ebay.com/itm/190904342772...84.m1497.l2649 .

I also replaced my fuel injectors with a set off ebay http://www.ebay.com/itm/Toyota-4Runner-Pickup-89-95-3VZE-3-0L-V6-upgrade-fuel-injectors-w-video-/261146725006?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1989%7CMake%3AToyota%7CModel%3A4Runner&hash=item3ccd8eca8e&vxp=mtr. They came with conversion harnesses.

mxoliver115

I got one of those off eBay and it wasn't fit the plug on my 88 knock sensor so I just soldered it on.

vegasrunner

dealing with mine with code 52 gonna dive in and check it all out. same problems too safe mode poor mpgs very little power. my ks actually disconnected at the pigtail when i was on a bumpy trail.