Error code 31

[NextLevel]

Hi Guys,

Havent been able to hit Mivec due to error code 31 (knock sensor).

So before I get started taking apart the engineto replace the knock sensor, I decided to do an expirement.

Attach the new knock sensor to somewhere else in the engine bay to see if the error code 31 would come up.

pluging in the new sensor.


screwing the knock sensor somewhere stable instead of the engine to see if the error code 31 would come up. (note, i have disconnected the battery to clear the error code)


here is the overview of what i have done:


in theory, the knock sensor will not hear the knock as it is not mounted on the engine block.
Therefore, the mivec should work (no 6000rpm cut) and no error code 31.

drove the car around normally (under 4000rpm) and check the error code. so far so good, no error deteched.

decided to rev the engine to 8000rpm, and behold the 6000rpm rev cut kicked in.

checked the ECU and the error code 31 is showing.

any suggestion on what is happening?

cheers

[Shane001]

I'm guessing the knock sensor uses earth from the engine and is not currently earthed correctly where you have it mounted.

[Bennoz]

You could not have plugged it in to a worse / more dangerous spot - a pressurized air con line. Its not going to give you any reading.

[Dras]

Keep in mind that the knock sensor is essentially a microphone. The ECU expects to hear normal combustion happening in time with what it believes the engine to be doing.

Knock is detected when a 'bang' is heard by the sensor while the piston is still moving upwards in the cylinder on its compression stroke. Where as, when a 'bang' is heard during the power stroke, the ECU knows knock did not occur and also that the sensor is fine.

When the ECU doesn't hear any bangs, it assumes the sensor is faulty.

[NextLevel]

Keep in mind that the knock sensor is essentially a microphone. The ECU expects to hear normal combustion happening in time with what it believes the engine to be doing.

Knock is detected when a 'bang' is heard by the sensor while the piston is still moving upwards in the cylinder on its compression stroke. Where as, when a 'bang' is heard during the power stroke, the ECU knows knock did not occur and also that the sensor is fine.

When the ECU doesn't hear any bangs, it assumes the sensor is faulty.

so the only way of knowing if the knock sensor is at fault is by installing the sensor in it's intended location? (in between the V of the block)

If it is indeed a knock that the sensor is picking up, what could be the cause?

I am currently running Shell 98 RON, and the ECU is dead stock and factory airbox.

cheers

[PHIL069]

The knock sensor is detecting when combustion (explosion) happens in the cylinders, this allows the ecu to time the engine correctly.

eg, if you change your fuel to 91 octane the combustion will happen at a different time, the knock sensor will detect this and in turn the ecu will adjust the timing to suit.

If you are getting a knock sensor error then the knock sensor is not sending information to the ecu, this can be caused by faulty sensor, faulty wiring input to the sensor, faulty output wiring from the sensor, faulty wiring from sensor to ecu, faulty ecu, (combustion in the cylinder not occuring, although unlikely cause).

If you test the knock sensor as you did you will always get a knock sensor error. Sorry but I lol'd when I saw your test

Install the sensor into it's intended location, if error remains start testing the wiring.

[PHIL069]

Some more info...

The knock sensor responds to spark knock caused by Pre-detonation of the Air/Fuel mixture. As the flame front moves out from the spark plug ignition point, pressure waves in the chamber crash into the piston or cylinder walls resulting in a sound known as a knock or ping. This is caused by using a fuel with a low octane rating, overheating, or over advanced timing. Sometimes it can be caused by hot carbon deposits on the piston or cylinder head that raise compression. A knock sensor is comprised of Piezoelectric materials; Crystals that when impacted, generate a voltage (same idea as a BBQ ignitor). This voltage is monitored by the computer, and when an irregularity is detected, the computer corrects timing in VVT (variable valve timing) engines.

It allows the engine to run with the ignition timing as far advanced as possible. The computer will continue to advance the timing until the knock sensor detects pinging. At that point the computer retards the ignition timing just enough for the pinging to stop.

A knock sensor assures that you're getting as much power and fuel economy as is possible from your engine.

[aza013]

I am currently running Shell 98 RON

There is your problem .

[Vectose]

Was about to say the same thing.

[NextLevel]

Thanks for the response guys, its back to the drawing board for me.

Damn how embarassing lol.

The current knock sensor on the engine does not error unless i try to rev over 6,000rpm.

Would this be an indication that my knock sensor is ok, and my engine is somehow pinging?

Cheers guys.


Btw, whats up with shells 98 RON (Vpower)?

[ZFL45H1]

Btw, whats up with shells 98 RON (Vpower)?

Blew Aza's engine up

[Dras]

Btw, whats up with shells 98 RON (Vpower)?

Blew Aza's engine up

I run Shell 98 (and have done for the last 5+ years) and have no problem hitting MIVEC or getting good power on the dyno, so it is likely not the cause.

First thing I would check is that you don't have coolant or oil entering the combustion chamber.

[ZFL45H1]

Think it was a bad batch and once something goes wrong u never trust it again

[Vectose]

It was the V-Power Racing 100RON that aza was using...

[ZFL45H1]

I stand corrected lol

[Technikhaus]

It was the V-Power Racing 100RON that aza was using...

Is it known why it caused it?
or was it just random...

[Vectose]

Why do you think they stopped selling it.... aza wasn't the only one to have problems.

[Dras]

This has been discussed in numerous other threads. Please stop spamming this thread.

[NextLevel]

Hmmm, im not quite convenice Vpower alone destroyed your engine.
Shouldnt the knock sensor retard the timing enough to prevent the engine from pining?
Anyways thanks for leting me know what happened.

I will continue to work on my car and try to resolve the issue. More pics to come.