I got this 4Runner 1995 3VZ-E engine, AT that had a head gasket replaced 6 years ago and started now with lock of power and engine stopping at traffic lights.
Had a problem with the EGR vacuum lines after the head gasket replacement but just ignored because did not have the proper manuals for the routing and probably messed up the hoses connections. Gave EGR code but just ignored since I do small trips in the area only.

Recently stumbled at traffic lights and engine could re-start with no problem. Very low power and rough idling. found codes: 12; 14; EGR; Knock Sensor 52; TPS; and Air temperature in.
Changed plugs and wires,; TPS even that seemed smooth on voltage checks; and the and Igniter. Wires helped because were in bad shape, Grounded better the Air Flow Sensor.
Checked distributor gap and shaft for high play but OK. Changed rotor and took Scope signal with Hantek 1008C (signal pictures attached) for NE; G1; and G2.They look reasonable to me.
Run a little better but something like irregular missing.
Reset all codes (OBD-1) and now only Code 14: No NE signal so the computer was now probably setting the engine on "Fails Safe Mode" I call it: Limping Mode but is the same,

I moved the computer from it place and twisted around trying to get connectors off and identify sources for NE;G1 and G2. Got the same signals back probing at the ECM connector with engine running.
But the car did started to run much better with no codes, in principle has more power (almost normal or little lower) in the driveway,
Took it Sunday for a long test drive and seemed to have some small difficult to detect hi-cups. Run it for long time changing gears, speed, anything I could think of and:
What I do not understand is that the engine goes into an up and down in RPM from about 1600 to 1800 cycling about two times/second with no accelerator changes. It is very pronounced if the car in in 2nd gear or 1st gear with the Auto-Transmissions, but also does it less likely if on Drive.
The Only code is 12 for Knock sensor. I understand by reading in this forum from Sheuffer or something like that is just a wire problem for no signal to the ECM.
Now how can a wire problem can be only happening at these slow RPM since the engine does not seem to be vibrating or the car I on a very smooth road.

My plan now is to hook up the Scope (PicoScope 2205A now, I returned the good Hantek with a sloppy software). I would try the signal at the ECM for the knock sensor.

Could it be that the knock sensor is just doing is job and getting the engine on Safe Mode because of pinging on the cylinders in the Block?
I must admit that when I did the head gaskets 6 years ago so I just placed the distributor in exactly the same place I found it and I did not check with timing light because it was running so good that I kept it.

I would appreciate any input or opinions since my experience level in troubleshooting is not very high.
As a bonus if someone can point to or explain how the rotor in the distributor with 24 teeth and G1ad G2 signal are incorporated in the strategy. Why 24 teeth. and why two coils G1 and G2?


At ECM

At ECM

At ECM

 

No.

I'm having trouble following your story (you might fix the typos; that could help), so I will only address code 52. The knock sensor is NOT like an oil pressure switch. Code 52 does NOT meaning your engine is knocking. The ECM and knock sensor work together, constantly advancing the timing until the engine just starts to knock, then retarding it. If the ECM loses contact with the knock sensor, it doesn't know where to put the timing, so to avoid damaging the engine with too-advanced timing, it retards it greatly. The code means "the ECM has not heard from the Knock sensor." That is why almost every piece of advice on this forum includes "replace the pigtail." You could check for the KNK signal at the ECM, but it is a very low-level signal and could be hard to pick up.

 

Sorry about my convoluted explanation. English is not my mother tongue and with age I go in circles.
Basically I cannot understand why the engine will cycle rapidly when test driving and slowly raising RPMs from approx. 1700 to 1800.
I cannot even think of how to untangle the massive set of cables going from the engine to the ECM on the passenger side of the firewall. There just no space to work.

I forgot to mention that the speedometer swings rapidly up and down at all speeds with the period of about 1/8of an inch.
Thanks for the FSM pages of the FSM.I bought just now a PDF all in one file but my PDF reader has not search capability so difficult to go thru 1,400 pages.

Plan of action:
Do a timing check with the light
Check with the PicoScope de signal at the ECM, I should see it even I have no idea of what does look like. If I do not see it. follow the advise on installing a Knock sensor on the engine lift metal tab with a shielded cable to the ECM directly.

I do not have or can find much information on OBD-1 since has long be superseded.
Thanks

 

Your language skills are fine (just imagine what I sound like if I have to post to a Russian-language forum). Everyone needs to watch for typos (especially when posting from a phone).

IF you have code 52, it's never going to run right (the ECM massively retards the timing to save the engine. If you try to advance the base timing to compensate, you'll really mess things up). So to verify that you DO have a real code 52, reset the codes (remove the EFI/MFI fuse for about 30 seconds). Then drive for about 10 minutes.

There are a handful of folks on this forum who have claimed success with an externally mounted knock sensor. Me, I just don't believe it. Why would Toyota carefully mount the knock sensor close to the center of the block (where it is difficult to service) when slapping it on the lifting eye is just as good? But it's your time/effort/money.

Looking for "information on OBD-1" is like looking for "information on soft-drink flavors." OBD-1 was never a standard; every manufacturer implemented it differently, and differently by model. Here's the page from the '93 manual; it should give you almost everything you want to know. http://web.archive.org/web/201211190...85diagnosi.pdf

Good luck!

 

It’s your ignition coil inside the distributor. Replace distributor and your all set. You can check the ohms of your coil which is inside the distributor and if you don’t have a manual I can upload a picture of that page on here. I can also upload a picture of the correct order of vacuum lines and whatever else you want.

 

Cameron, is I assume referring to your questions about the 12 codes.

The images the OP shows are of the NE, G1 ,G2 signals taken by oscilloscope at the ECU. This means he has good signals and his code was due to "at some point" (most likely..) Not having the dist connected and not clearing the codes..

OP it's 24 teeth, six cylinders in four positions.. Six times four equals 24 teeth.

 

I had Code 52 and my coil was the problem at least just check it I went through everything you are for 2 months and it was the coil in my distributor. Takes 5 minutes to check.

 

If you are of a certain age (old), you might remember a cartoon starring Augie-Doggie and Doggie-Daddy. I still recall Doggie-Daddy lamenting the condition of his car, opining that "the carburetor is interfering with the differential."

I am at a loss to guess how a problem with the ignition signal generators could cause the "signal from Knock Sensor not input to ECM in 6 revolutions." But, if you want to check the resistance and air gap of the three signal generator coils, here's the FSM section: http://web.archive.org/web/201212070...12onvehicl.pdf

I suppose that the pushing and pulling on the harness that could be involved in replacing a distributor (or anything else) might cause a broken wire to reconnect. Temporarily.

But if you want to just try replacing the distributor, you can get a new one online for only about $675.00 (probably more at a brick-and-mortar dealer). Your choice.

 

I had the same problem he’s having with code 52 it would hiccup constantly. This was 2 years ago, but a distributor cost 170 at autozone for me. All I’m asking and implying is that he at least check it. I was up late last night and figured I could help some people who are having the same problems I had. This will be the last time I post to help someone.

 

_PUIt is perfectly fine for you to help.

Co_94_PU and Scope103 were basically saying that you shouldn't replace parts simply based on a guess. You may have had similar symptoms, but not necessarily the same problem(s).

Your first two sentences of your first post basically state that the distributor has got to be the problem. Essentially, Co_94_PU and Scope103 were saying that your sentences were pretty definitive, and a better way to state your first two sentences would be: "I had a very similar symptom and a new distributor fixed the problem. Check out the distributor pickup coil and gap using the Factory Repair Manual to see if yours is good."

In the end, that is probably what you meant. It is harder to tell what someone means over the internet than in person.

 

Old87, there is also some discrepancy about the codes going on.

52 is the knock sensor signal
12-14 are ignition trigger signals.

In the first post we are looking at the signals from the distributor (through the ignitor) as measured at the ECU. Which look OK for the timespan we are looking at. A longer time span wouldn't hurt (so we might spot a missing pulse), nor would having a three channel scope (which let's you line everything up on the same time base, but that's not needed here really it just looks nice.)

Fermin's current issue, paraphrased, is rpm not stable, low power output and a code 52. The trouble shooting mantra is "Fix the codes first".

In this case the two complaints are directly related to the code, in addition to this chasing a vacuum leak that might be causing rpm fluctuations is a waste of time because it " all " has to come apart to put the sensor where it's supposed to be..

..
Cameron's solution is valid in a lot of cases for a crank/cam/ignition problem. Personally I'd spend the better part of a dayaking sure I had good wires and solid connection from A to B before changing out a distributor on a hunch or someone suggestion. Of course I don't have to pay by the hour for troubleshooting electronic issues, and based on the information provided by Fermin he doesn't either.