95 4runner 3.0 V6 rough idle, no accel, code 52

Hello all.

I recently purchased this 95 4runner with the 3 liter 3vz-e V6. 166K miles. its got a check engine light and using the jumper wire on the diag port, it gives me 1 code, code 52(knock sensor). Ive read that these are problematic on these motors, but the symptoms make me think it isnt just a bad knock sensor.

The car cranks and idles, but its a little rough, sometimes smooth, sometimes not. when you go to drive, it just crawls. mash it to WOT and barely changes anything.

its xmas day and my tools are limited and stores are closed so i cant go get anything. my vacuum guage is inop(great!). i do have my multimeter though.
The other day when i bought it, i picked up the basic replacement tune up parts cause they looked pretty dusty when checked it out. got new plugs, wires, dizzy cap and rotor, new battery. I have no history on this vehicle other than checking the vin against recalls and it shows 0 due, so the head gasket recall must have been done in the past.

i checked the distributor with the multimeter and it was good, checked the ignition coil and the cold reading is supposed to be .36 - .55 ohms and it was .6 ...but all the wires are getting spark and the plugs are getting spark, and each cylinder is contributing to power...pulled wires 1 at a time and noticably changed the idle.

I checked the injectors with a stehoscope and all of them are clicking. the drivers side row is pretty difficult to get to in order to remove, and the passenger side ones are under the intake mani, could just barely get the stethoscope on them, so i havent ran the meter on those yet.

heres where it gets worse. I ran the jumper on the diag port to check the timing. as it sat, the distributor was rotated max counterclockwise and was reading 11-14 BTDC(spec is 10) idling rough but at 800ish rpm which is what is called for. when i rotate the dizzy to about 60% of the allowable adjustment to the clockwise direction, the idle becomes smoother however its idling at 1100 and the timing mark on the harmonic balancer then reads well past the last marking of 14BTDC, so id have to guess something like 20-25BTDC. the car then is able to be driven up and down the road. it still feels like its got a slight misfire and definitely still cant reach max acceleration or top speed. so its definitely still wrong.

as soon as tomorrow rolls around im gonna go get a new vacuum guage and run those checks, but the timing thing is making me think that maybe a timing belt job was done and theyve got the belt on wrong by a tooth or something. thats my best guess right now.

would love to hear your thoughts. thanks.

How does it run if you turn the distributer back to get it to 10* btdc? I would agree that something is wrong if it runs better at "20*". You said sometimes it runs good though? Is that only at idle?

If it's too advanced it would detonate with some load and the knock sensors wouldn't like that (well, maybe they would since it's their job) but I'm not sure what that KS code description is. If base timing is too retarded the engine can overheat.

Is it difficult to check mechanical timing on these to see if everything is lined up?

Initially when I read no power descriptions like this I instantly think of timing and plugged exhausts.





Nissan Tech

Well it only gets close to 10, more like 11 when the distributor is turned to the max amount allowable counterclockwise. and thats basically how it was when i got it. its rough at idle and crawls. feels like a bad misfire and wont go more than like 2mph with any amount of throttle. at either timing setting, i have rand the car for around 10 minutes and have not noticed any overheating.

i am going to be doing valve cover gaskets as they are leaking, so if im gonna tear the intake down that far, its only a few more steps to get the front cover off to check the actual timing of the cam pulleys and crank. i suppose firstly, i could drop the cat and check that out.

edit: found an FSM and the 52 code for knock sensor has more detail saying it must either be a short inside the ks, the ks is loose, or pcm bad. says it sets the code With engine speed between 1,600 rpm – 5,200 rpm, signal from knock sensor is not input to ECM for 6 revolutions.

so the ks is definitely bad and i will be replacing it...still gonna check the cat and the physical timing.

Out of curiosity, does this have a 16 pin dlc connector under the dash somewhere? I think there are a handful of 1995 cars that had it prior to the federal requirement?



Nissan Tech

it has the diagnostic port under the hood, thats what i referring to jumping when i talked about the timing and checking the codes.
https://imgur.com/9fZc490

on that you jumper the E1 and TE1 ports in order to check timing or check eng codes.

video of vacuum

looking like worn valve guides and incorrect valve timing from that vacuum reading if im correct. also that should be showing the exhaust is not clogged.
looks like i might be taking the heads in for a valve job.


i started the teardown to get to the knock sensor which is under the lower intake plenum...fun. it appears that the knock sensor is brand new been changed recently....but get this... the connector wasnt fully seated . some peoples kids. i bet they let the timing belt jump a tooth when it was all apart since the lower plenum has a timing pulley built onto the front of it, loses tension when the plenum comes off. i cant really tell how old the timing belt is but it has no cracking...still might just toss a new one on since im here.

if you all have any other thoughts lemme know. itll be a few weeks til im putting this all back together.