bksr5

From what I've seen, I'd check for corrosion at the KS. I use dielectric grease on every connector I ever deal with.

Bob K

dropzone

iTrader: (6)

FYI: thread has been cleaned up to eliminate some crap that was going on in the thread and try to maintain the tech of the thread.

waskillywabbit

iTrader: (-1)

Opened and approved.

bksr5

Thanks for all the work. Looks great, much better w/o all the BS.

Bob K

crazycruzjr

ok my truck is setting this code because after i switched engines the new engine didnt have threads to mount the knock sensor so how can i fix that
thanks crazycruzjr

fuzzysnuggleduck

Long time lurker here.

I just felt like sharing my success fixing good ol' code 52 since I've learned so much just reading this forum.

I started getting the CEL about 1.5 years ago in my 1991 4Runner with the 3VZ-E. At first, it was a rare occurance and would only come on when the engine was cold. If I drove it a while to warm it up, then shut it off and turned it back only, the CEL wouldn't come back until the truck was cold again. Eventually it just got worse and worse to the point where it would just come back on reliably, no matter how hot the truck was. I was pretty annoyed and upset about it because have been putting good money into the truck over the years (tires, timing belt, suspension, steering, alt, etc.)

So after reading all the advice on yotatech, I decided to just do the Right Thing (TM) and tear off the air chamber (plenum) and intake manifold to replace the sensor and the pig tail. I had considered the mounting of the KS in the lift hook hack but just didn't think that this was the long term solution that I wanted so I avoided doing it "just to get by".

Anyways, long story short: It's a heck of a lot of work to replace that sensor and the pigtail.

A few of the annoying things are:

1. It's impossible to test the pigtail and the sensor separately without tearing everything apart so while your sensor might very well still be good and the pigtail is likely the problem, it's too risky to tear the top off the engine and NOT replace the sensor as well... and the sensor is expensive.

2. The plenum has a ton of vacuum lines connected to it. Label them all when you're tearing the plenum off!

3. To remove the intake manifold, you have to remove the timing belt idler pulley which means risking messing up your timing. We clamped the belt to the camshaft pulleys while removing the idler pulley and everything stayed well in place. But regardless, pulling the timing apart to remove the intake manifold sucks. The idler pulley also happens to be the channel where the hot coolant comes out of the intake manifold and goes back into the radiator... strange design.

4. After 350,000k, the intake manifold and plenum gets REALLY dirty with carbon build up. Cleaning that out was a huge pain but while it's off the truck, it only makes sense to clean everything as best as possible. On the positive side, I did remove the valve covers to replace the gaskets while I was in there and the cams looked great for 350,000k.

The whole job took me and my friends the entire weekend as we had to research, do the work, label stuff, clean, drink beer and what not. Not to scare anyone off, but it is a lot of work.

However, I can report complete success! No more code 52 after replacing the sensor and the pigtail. Nothing else special was done. Both the sensor and the pigtail looked like crap coming out. The pigtail was just totally stiff and brittle and the sensor was looking old, dirty and probably passed its prime. I finally have some power back... and no more extraneous gas guzzling. The 3VZ-E always kind of guzzles but when the CEL came on, it was brutal mileage.

So all concerned home mechanics: It can be done! Just book a weekend and GIVE-ER!

McVeigh

I need some recommendations on how to proceed with my code 52 issue. Here is my story. . .
I’ve owned my 94 PU 3.0 for some time now and have always tried to stay on top of maintenance with my truck. I love it and like to take care of it. The last year or so I had a serious loss of power and fuel economy, however no CEL or anything like that. I just attributed it to having about 200K on it. Later my mechanic thought it was a bad valve and it needed new seals so after weighing the price of that against a new engine, I opted to put in a rebuilt. I looked around online for a NW rebuilder and ended up going with Oregon Engines (oregonengines.com) out of Sandy, OR near Portland. I went with their “superstock” 3.0 rebuild which just has slightly bigger valves and cam. Since I was in the process of moving back to WA from CA I asked them if they did installs as well. They said they did, so I decided on the one stop shopping and had them do the install. They put new injectors in and replaced a good deal of other parts (knock sensor and pigtail included) you’d expect. After they got it back together and drove it they had knock sensor and/or vacuum issues where the truck would idle real rough with no power when cruising and weirdly would run worse if you pulled the dipstick out. They took it to a dyno guy and supposedly addressed those. Later they had code 52 issues and took it back to the dyno guy who said a sensor in the distributor was bad and they replaced that too, CES went away and then I picked it up. Right away I noticed the rough idle and loss of power that it had before I brought it in!!! So I took my truck to my long time mechanic who puzzled over it for a day and this is what he came up with:
There is low vacuum, reading only about 10 where he expected 15 to 18
The timing was set way ahead (supposedly by the dyno guy) to 22 (maybe to compensate for the code 52 and CEL)
When he set the base timing to the correct degree the CES would come on with code 52.
He played a little with the air flow meter and the idle to help it not idle so rough, but it didn’t do much.
It still runs worse at idle if you pull the dipstick.
We put another PCV in from a 3.0 he had as the aftermarket one Oregon engines put in was making some funny noises when played with. That helped a little. . .maybe.
I’m getting irritated to say the least and just want my old truck back. Not the poorly idling, bad gas mileage, powerless piece I have now. Please help.
So, now I’ve read a bit about the code 52 issue and specifically what Shaeff has written about the subject and was hoping for some advice. I’m back in WA now (Seattle Snohomish area) and don’t have a mechanic here. I really like the advice about this code 52 issue and am wondering if anyone knows a mechanic in this area who can pull this off OR a some advice on what to request to a shop if I just roll in. Or can I do some work myself? I’m not a master mechanic, but can find my way around an engine. Thanks for reading and any help!!!

mitfan311

Ok guys I have been reading through all of this and I am more confused than ever. I have a new knock sensor. I took a long red stereo speaker wire and coiled it up onto the one prong that comes off of the knock sensor. then I snapped the original wiring harness back on. Why does the one wire become two after several inches? The red wire was a back up that i ran out with the rest of it. My plan was to run it straight to the ECU if the wiring was bad. So it turns out the wiring is bad. I can reach in there and jiggle it a little an it will run fine then after a few bumps it loses connection again. So if I have this one red wire ( the backup wire connected directly to the knock sensor prong), and there are two going to the ECU then which one do I hook it up to? By the way its a 1995 3.0vze

scope103

huh? Do you mean you took a piece of cheap-ass zip cord (speaker wire), and WRAPPED one conductor around the 1/4" spade connector on the Knock Sensor?

The Knock sensor pig tail is shielded. Not grounded at the Knock sensor, but at the ECM end.


You want to replace a factory, shielded pigtail with molded connectors with a an unshielded piece of wire that is just lightly wrapped around the connector? Do you have any reason to think that is more likely to resist vibration than your broken pigtail?

If you want to try, the sensor wire is black, and the ground is black with red, according to my 1994 wiring diagram. But as much work as it is to get to that pigtail and replace it, I think replacing the pigtail is by far the "easier" way to go.

bob hennig

Pig tail wire from knock sensor is 2 prong at connector, one at sensor because the other prong is a floating shiold to protect signal on circuit. check wire at conne=ctor and the one prong will go directly to ground, this one should be left. connect your wire fron the KS to the other which feeds the ecu. It may or may not work as the pig tail is shielded in the original set up to protect from stray EMF internal in engine and wiring harness area. Give it a try. Not working will need to follow diagnostics.

cowb0y

Would anyone post pictures of the knock sensor, pigtail and connection to ecu? I have a '91 3VZE and cant seem to find the pigtail.

Sannoman

Ok so i was having the same error code for my 95 pickup, which has a 3VZE engine. Since there is no room to get to the knock sensor. we had to pull the air intake hose that connects to the throttle body. When we took the hose i discovered a large crack. I taped up the the crack and now the check engine light doesnt go on anymore. Maybe this was covered earlier but hopefully it might help someone.

Ricky B

Kwik question Kidz.....with the negative cable disco'd from the battery, should I be seeing continuity from the engine block to BOTH of the wires at the female end of the harness connector that plugs into the pigtail (that goes to the knock sensor)? Or just from one of them?

(Sorry to rehash this great thread but I'm about 11 hours and 37 minutes away from just letting off the emergency brake on this '91 and let her roll into the freakin' harbor).......

Ricky B

Anyone? Pretty please? With bacon on top?........

shaeff

You should see continuity to the shield wire, not to the center conductor. If you get continuity between the center conductor and ground, that will cause code 52.

Ricky B

Thank you, Sir.

(I knew you would finally wake up this week)......

shaeff

Haha, no problem, Ricky. Often times it looks like I'm here (online) but this is one of my four home pages.

If, for some reason you need me to check back in, you could always shoot me a PM- as it would pop up as soon as I open the internet.

Ricky B

Most excellent Shaef, thanx agian. Now then, let me see if I comprende what you said----if the center wire is 'grounding' out on the block, that tells me that somewhere between the knock sensor/pigtail and the ECU, the center wire is cracked and/or worn somewhere and is touching/shorted to ground, yes? So if I stick my DVM probes into the center wire terminal and to engine ground somewhere, (thereby causing my meter to beep continuously) and then start moving the harness wires around until I hit something that makes the beep stop, that should mean that I've struck oil and found the bad spot? Make any sense?.......

(btw, I'd like to take a moment to personally thank Mr. Joe Toyota for building a truck that only requires 2-1/2 hours to replace the starter on. 'Cuz I'm pretty damn sure that you could have really gotten sloppy in your design by burying that thing even farther, thereby making it a 6 hour job).......

Ricky B

Hey Shaef, is this your work? If so, well friggen done.....


http://www.turboninjas.com/supra/knocksensor_rewire.pdf

shaeff

No problem. Basically this:

The wire that goes to the ECU- actually INto the ECU should never see ground. The shielding wire should always see ground. The center conductor wire is what goes to the ECU, the outer shield should be grounded.

And yep, you've got it.


That's not me, but it's kinda the same principle. Here's one of mine for a MKIII Supra:


I put my ground on the inside of the cabin, not in the engine bay. Less likely to fall victim to corrosion. Also only ground ONE side, lest we make ground loops which are not a good thing.