Engine throwing codes 42 and 52... may need a new knock sensor...

[Drake69]

I just got two codes from my ECU this morning and am pretty sure what one of them is caused by. The code 42 being the vehicle speed sensor which is probably left over from when I swapped out my speedo cable, and another code 52 which is the knock sensor. I'll be looking into replacing that one if anyone has any spares, but I'll clear the codes out to make sure the code 42 doesn't resurface.

So... anyone have any rod knock sensors lying around? I heard there's a newer sensor on ??? Tacomas ??? I think that might work if no one has any available, but not sure about the fitment. :1zhelp:

 

[ogre]

I've got 2 of them from my 7mgte I just pulled out , the motor actually ran it just had a blown head gasket , it wasn't throwing any code make an offer... This will probably get deleted because I havent reached my 60 posts yet...

 

[jdub]

Clear the codes and drive...then recheck. If the code 52 is still there, it's most likely the wiring and not the sensor itself.

 

[Drake69]

Yup, code 52 keeps popping up (42 cleared after I pulled the chip, yippee!!). So, if it's in the wiring, what do I check first?

 

[92nsx]

Ohm out K1 to ground on the ecu and K2 to the ground on the ecu. There should not be continuity between the two.

When I had my code 52, the shielding was wore threw in one spot on K1 and touching the wire. I got lucky with mine, the trouble spot was right at the end of the wire on the knock sensor side and was a e-z fix.

There is several thread out there on how to re-wire your knock sensors.

 

[Drake69]

I'm going to have to find someone local that knows wiring and grounds to figure out this rod knock sensor thing, or at least some pics of how the sensors wire up so I can bypass them completely (not an option I'm comfortable with). I'd rather keep the sensors as they are part of maintaining my engine, and remember someone mentioning a Tacoma (??? I think ???) RKS being a good replacement as the plugs are the same. If this is true, what year and model Toyota truck would I need to find to get these sensors and replace them with? Would I have to go dealership for them new? And isn't it inherently dangerous for my motor to bypass the sensors altogether? Ohh, and my car is an '88 GTE just as a reminder.

Any :1zhelp: would be appreciated. Searching for the replacement stuff here is not finding what I need (didn't type in Tacoma specifically though...).

EDIT: 4Runner, I was kinda close...

 

[Drake69]

Should've read further...

On an almost unrelated note, I found a few knock sensors on Ebay back a couple of years ago out of a 90's Toyota 4Runner, and put them in since they were newer. If you ever have a knock sensor definitely go bad, you can use the 4runner's, just gotta splice in the newer connectors- and I figured why not? My old ones are shabby, and I was splicing them to all new coax for the rewire anyway.

That's what I'll probably replace them with, just because they're newer. Now if I can find the procedure for the rewire to the new sensors, I should be golden.

 

[Drake69]

Don't mind me, I'm just merging this stuff to have a good printout on what to sniff for...

the o2 and knock sensors are shielded wires...sort of like a coax in a radio system. its a signal core and a shield wire on the outside. (2 wires and 2 sets of insulations all in 1 wire) with old harnesses like mine, if the insulation gets brittle and bends, both insulations gets cracked and the shield wire can make contact on the signal wire. if the harness is good then it might just be a bad sensor...i dont know how common these go out

The knock sensors are under the intake manifold on the side of the block. There are two on a turbo car and one on an N/A.

1 is almost in line with the strut tower and the other is at the back of the block if that helps, single wire connectors should be green...IF you can even see down there, a mechanics mirror should help a lot

Dammit, need to keep better track of my questions...

 

[Drake69]

Now I REALLY feel like a frickin' idiot....

http://www.supramania.com/forums/showthread.php?t=105505&highlight=knock+sensor

Shaeff and jdub, all you guys rock...

 

[--Golli]

http://www.supramania.com/forums/showthread.php?t=105505

Read it.
Do this before you waste your money on knock sensors.
As stated here....

...it's most likely the wiring and not the sensor itself.

it would save you a nice sum of money...

 

[Drake69]

Yup, figured it was more wiring specific stuff than I can handle. Will see if I can nab a friend of mine to assist in wiring this all up.

Thanks again!:icon_bigg

 

[jdub]

I'm pretty sure Shaeff still sells a premade KS replacement harness...it would be worth a PM to him.

 

[Drake69]

Done! Thanks! :icon_bigg

 

[Drake69]

Sorry to resurrect my old Code 52 rod knock thread, but this is important. After much searching, I found a VERY IMPORTANT pic of an engine bay that outlines EXACTLY where the rod knock sensors are and had to bring it to the forefront and post it here for everybody to see.

As you can see the sensors are under the intake manifold, so you have to get to them from below, NOT ABOVE. In addition, the 86.5 to 88 years don't have to remove the starter to get to the rear sensor, but the later models you do. Between this and Shaeff's cables he sells, this makes bypassing the old cabling that much easier.

I couldn't believe how many abandoned threads I found about the problem, with some people recommending just running without the sensors hooked up, selling Shaeff's kits without even trying to put them on, etc. BTW, not running the sensors causes the limp mode in the ECU to engage, which riches out your fuel mixture and seriously degrades engine performance to prohibit "further engine trouble" (the problem is in the sensor or the cable, NOT the engine!!!!).

Still need to find a local soldering guru (my friend can't help me on this for awhile), and FYI, soldering these cables into the ECU and not crimping/twisting them is a MUST. Shouldn't take me long tho.

 

[Drake69]

Shaeff's cables did the trick. I was running in limp mode the entire time I had the car, from August of '09. The code is gone, and now it runs even faster than when I did the 3" exhaust. Thanks for everyone's help, and be sure to try out Shaeff's cables as a cheap-easy fix to a nagging problem.