Gamefreakgc

Yes, that's what I was talking about. The PAIR valve should only stay open for a short amount of time. For me in 30ish degree mornings here in California, that's usually about 2 minutes. If it's taking a very long time or never stops gurling when throttle is applied then there is an issue.

I'm not sure if the ECU does see RPMs... but I do know that it does see the engine temp through the Engine Coolant Temperature sensor on the water bypass on the back (green or gray plug) and the TPS. If the TPS is somehow always showing an "idle" reading that would do it, it would need adjustment or replacement. The ECT is just a sensor, it works or it doesn't. The ECT is known to cause a host of different issues when it starts to fail.

These are not sure fire fixes but are fairly straightforward to check with a multimeter set to ohms and a feeler gauge without having to buy or replace anything yet. Refer to the service manual for specs. The TPS is much easier to adjust with two people unless you have little clips for the multimeter. Once you start you'll see what I mean, since you have to rotate it and hold the probes on the connector at the same time.

Team420

The ecu does read rpm and coolant temp...

The ecu does not look for signal from the knock sensor till 1700 rpm....

its 99% likely its the pigtail causing the problem, BUT... if youre going to go thru the trouble of changing the pigtail (remove upper plenum, manifold etc...) you would be wise to replace the sensor while youre in there... I changed just the pigtail when I had the 52 code, tossed it all back together, and still had the stupid code, so apart it all came again to replace the sensor, and then the code was gone.

mxoliver115

I came across something last night. Just checking the vacuum hoses with the book. Specifically the 3 small ones that go to the egr. Its unclear in the manual but I used marker followed each line and I had 2 lines reversed. 100% better. Runs like it should . now I just need to fix the ks. Just double check. I bought mine this way.

mxoliver115

I replaced the knock sensor and pigtail twice. Yesterday with a brand new sensor an today with an old one.I'm so tired of this. It looks like a 3.4 in the future. Any way. I discovered many things. First my hesitation. I had a air leak in the manifold. Spiratic idle, hesitation when warm and lousy throttle response and white plugs.
Second I found globs of fiber glass material in the sensor manifold. I took out all the sensors and flushed that thing out.I didn't realize how small the hole is. So comes to my last problem. While putting it together ,Ground on the knock sensor wire ,there was only a few strands of wire on it. The main wire is perfect and I tested it to be continuous. Could this be my problem of code 52?

scope103

Yes, the shield is there for a reason. If you lose enough of it (particularly if you lose continuity) it won't work. Which means code 52.

Others on this site have reported success replacing the wire from the engine to the pigtail with "ordinary" shielded wire (no point horsing around trying to make a pigtail; brand new OEM is only about $12).

mxoliver115

So I gave in and took it to the shop. 100 bones to have it tested. The wire tested good. The knock sensor was bad. A little advice. Don't put China sensors in. 3 of them didn't work and a lot of waised time.and my hesitation is gone. Corrected wrong vac lines and sealed intake gaskets. Cleaned temperature sensor manifold so my sensors work and no more sloshing sound.No one seems to post their fixes so I hope this helps some one else out.

Menace94runner

Hello I am a new member of Yota Tech and a new owner of a 94 4Runner.
I took it into a shop to get a check engine light diagnosed. It came up as a knock sensor code. So I took the upper and lower intake off and replaced the knock sensor and the pig tail. The old pigtail was soldered in off of TV Cable Co Axial wire. So I bought a new pigtail and went to install it but the previous owner spliced in behind the harness. So I took it further back clipped the new 2 point connecter, stripped the wire and soldered the existing shielding to the new harness shielding and did the same with the core.
The truck runs well but has a check engine light again. I am fairly confident that I did not cross the wires (shield to shield, core to core). Is this a common issue. My truck seems to advance fine but I do not want to keep fighting this issue. Any ideas? I am thinking of taking it to get the wiring harness checked.

Gevo

Hello Menace, and welcome.

Actually you can check the codes yourself relatively easiler (I am assuming it is the same system as my 91, other members smack me if this is incorrect!)

I would suggest checking the harness yourself, it can take hours and a mechanic will charge you a lot of money to find and repair it.. if you don't mind that then clearly it's the easier choice!. But dont' be afraid to check the wiring yourself. It's only two wires and should be very easy to check for continuity individually and to ground, and check resistance as well. Find the wiring diagram here, (should be on of the engine control diagrams) http://snjschmidt.com/wiring/ , and the FSM here http://personal.utulsa.edu/~nathan-b...27troubles.pdf . If you need more helps just write it up here. You should also write back and let us know how you solved the problem.

good luck.

Gamefreakgc

Sorry bro, looks like the last owner didn't know what the heck they were doing in there.


If you are confident in your wiring repairs, it's the sensor this time. But it could still be a short. If you can, try and tap the wire (google wire tap) and see if there's voltage going through those wires before you rip it apart. If not, it's a wiring issue. If yes, I would assume it's the sensor. That's not a sure fire fix... a sure way to do it is too research the wire colors on which is which (find a wiring diagram) and replace the sensor...