Code 43: Electronic Spark Control

1992 Jimmy, 4.3L (w), 4x4, 4 door. 90,000 Miles.

Recently the Service Engine Soon light turns intermittently on and off. I pulled Code 43 from the computer and reset it but it came back. I did the test where a timing light is hooked up and pointed at the timing marks while the drivers side block is struck to simulate spark knock and observed no retarding of the timing.
(I did unplug that wire, like when checking for base timing. Should I have kept it connected?)

I believe there is no ESC module, as it's not on the firewall where it should be.

So I suspect that the Knock Sensors have gone faulty. When trying to remove the one on the drivers side I found that a 22mm & a 7/8" wrench or socket will fit, but will slip off and round out the nut. A 21mm or a 13/16" will not fit. A crescent wrench does not have enough room, so now I'm down to considering vise-grips.

The dilemma is that I want to take the knock Sensors out of my parts truck and reuse them in my truck and if vise-grips do work, the nut portion will no doubt be ruined.

Questions:
Is there a special tool for removal?
Should I use heat?
Why don't my quality wrenches & sockets fit?
Am I on the right track?
Do knock sensors penetrate the water jacket?
I know where the knock sensor is on the driver side, but on the passenger side is it on the back of the block?

Any help would be awesome.

thanks

the other knock sensor is on the rear of the engine by the transmission dipstick. I know because we knocked it off with the dipstick when installing the tranny.

MT, Master where are you guys?

This is what I dug up:

"Knock, Knock -- Forget The Hammer Trick
To test the knock sensor, some techs grab a hammer and tap on the block. While tapping, they look for spark retard. But most techs don’t know how smart this sensor really is. The knock sensor in this engine is tuned to 7,000Hz, the frequency range of a spark knock condition. With that narrow range of sensitivity, the computer can’t hear a noisy idler, worn cam lobes, rod bearings or a frustrated tech banging on the block with a hammer!

Getting no retard out of the hammer test, many techs pull off the intake manifold and replace the $130 knock sensor. They’re shocked to find the same code 52 on their next road test. Now what?

The cause of the code 52 problem is usually not the knock sensor itself, but the signal wire between the knock sensor and the external connector by the intake manifold. This wire gets brittle if it is overheated. Removing the connector during disassembly can break the signal wire inside the shield. Obviously, that prevents the signal from getting to the PCM.

We advise techs to replace this short length of knock sensor lead wire any time the intake manifold is removed. Especially if it’s been overheated.

Knock, Knock--It Can’t Hear You
The Resonance-style Knock Sensor Will Not Respond To Your Hammer Blows
Back in engine performance class you probably learned that there are two common types of knock sensors -- piezoelectric and piezoresistive. The piezoelectric sensor creates a voltage when it is exposed to vibration, while the piezoresistive type changes resistance during vibration.

That information stills holds. However, in addition to the two types of sensors, there are two different styles of piezoelectric sensors -- mass and resonance. The mass sensor has its "ears" up to all vibrations. It produces a voltage at all vibration frequencies, creating its highest voltage at around 7,000Hz. This sensor forces the PCM to filter out the voltages above and below those generated at the 7,000Hz level.

The resonance sensor is much smarter. It sends a significant voltage to the PCM only when it detects vibration in the 7,000Hz range. At all other times it is quiet as a mouse. This self-monitoring takes a load off the PCM.

While Toyota uses both styles of piezoelectric sensors on its engines, the engine on the reverse side of this page uses only the resonance style. Unlike knock sensors from other manufacturers, striking near this sensor with a hammer will most likely get you nowhere, unless you are just looking to vent some frustration.

About the only way to test this sensor is to over-advance the timing, attach your digital meter (AC scale), and take the truck for a test drive. If the sensor is working, you should see AC readings that correspond to the pinging you hear. "

http://www.asashop.org/autoinc/JULY/techtips.htm

What codes are you getting 43 or 52 or both?
The 4.3 does not have sensors under the intake.
What voltage is the knock line have on it with sensor/sensors hooked up key on?

It was code 43 only. That article was only to explain that hitting the block is not a reliable way to test knock sensors.

Drivers side 2.22v and passenger side 2.46v. with ignition on and engine off.

In my book it states that "Code 43 indicates that the ECM is receiving less then 6 volts for a 4 second period with the engine running."

Also to note, I just reattached the small vacuum line on the throat of the intake manifold that had again slipped off.


Thanks MT,

It was code 43 only. That article was only to explain that hitting the block is not a reliable way to test knock sensors.

Drivers side 2.22v and passenger side 2.46v. with ignition on and engine off.

In my book it states that "Code 43 indicates that the ECM is receiving less then 6 volts for a 4 second period with the engine running."

Also to note, I just reattached the small vacuum line on the throat of the intake manifold that had again slipped off.


Thanks MT,

The knock sensor line should have 5 volts sensors unpluged and around 2.5 volts with them pluged in.

Your sensor pluged in voltage is good.
Now unplug them and measure resistance of both sensors.
They should have 8.5-8.25K ohms restistance.
And check for 5 volts on sernsor linre with sensors unpluged.
On the tap test You may have to hold brake and put engine in gear if auto matic to run test.

There is a lot of confusion on different knock sensor systems and voltage.
Like dual or signal sensors and with or without spark control and and turbo or non turbo.
A good engine capable scanner should read out if it is getting a knock signal or not.
Most knock sensor codes are caused by wiring and sensor plugin problems ad wiring to close to ign and other stuff.
Check you wiring and plugins real good.
Also a bad ecm can giive problems.
Good Luck
And let us know how it goes.
MT