Knock Sensor Operation

[shades2]

On some cars, if knock is detected, the ECU/ECM will put the car into a limp-home mode to stop you revving it, creating detonation, and potentially causing major damage to one or more cylinders/pistons.

[zoharp55]

HTC evo vs iphone guy???

[carveriscool]

I got a check engine light in my 1997 Subaru Impreza. It's a knock sensor code. There is a HUGE difference in acceleration when the check engine light (for the knock sensor) is on than when it's off.

[ADPTraining]

@carveriscool Yes, the knocking engine or perceived knock (assuming the sensor is giving an erroneous faulty reading) makes the ECM retard ignition timing. Try and disconnect the sensor and see what happens. THis may not solve your issue. Some systems sense a disconnected sensor and put out a code and retard timing. Good luck.

[shades2]

@carveriscool Try changing your fuel to premium unleaded, add octane booster if necessary and see if that's the issue. Otherwise you might need to replace the sensor, or the engine have some other fault with timing etc. The ECU/ECM is trying to put the car into a limp-home mode I think to stop the knock/detonation damaging the engine.

[carveriscool]

@shades2 I already ordered a new knock sensor a couple weeks ago.

[shades2]

@carveriscool Cool. Did it fix the prob?

[StinkyTaco]

I didn't know stephen hawking was a mechanic...

[FernterPix]

When the mechanic had it hooked up to the dang computer and got it to do it's stuttering,it gave the Knock Sensor code as the problem. What could cause the false/misleading reading?

[ADPTraining]

@FernterPix OK, first I can tell you that Nissan Knock sensors are always faulty after 50K miles or so. No biggie, that's not your issue. You have a misfire, either ignition, injector or valve problems (not likely). The knock on your vehicle is in the cylinder valley, under the intake. It is hard to get to and expensive to replace. Before you replace the knock get a proper diagnosis. Look in the areas mentioned. Post back when you get it fixed or done please, just to help others. THanks...

[FernterPix]

Would the Knock sensor make an engine hesitate while accelerating at a given speed? While cruising along around 50 mph and then giving it gas,the Xterra will "stutter" during acceleration.Once I'm passed a certain speed it seems to go away and is more evident during colder weather.

[ADPTraining]

@FernterPix Hello, well in your case the answer is no. On Nissans the knock sensor has an effect on timing, but not enough to cause hesitation. On other makes it is possible. It sounds like an ignition problem. Do a power brake test. Set parking brake on, step on brakes hard, set trans in drive and goose the accel pedal for up to 5 seconds (not longer). If hesitation is detected then suspect ignition problem. Post abck with more...

[FlyerShip]

the explanation and video are good but that dam voice is annoying!!!

[tainle]

i have a nissan 2003 maxima and i have ping/rattle sound when acellerating from 1500-3000 rpms. pinging and rattle very little and to no pinging if it driving at 30mph without adding any gas. but it make noise when adding gast between 1500-3000rpm. this pinging start to happen when engine at operation temperature. bought car at 96k and now almost 104k. this video make me to believe it the knock sensor. could that be it?

[ADPTraining]

@tainle Hello, very nice description, well done. OK, the knock sensor will not cause pinging and won't give issues other than the check-eng light on. From your description you should look into the EGR valve. Look to either EGR valve clogged, EGR vacuum hoses, or EGR solenoid. This description fits perfectly with an EGR system failure. Good luck and keep posting...

[tainle]

@ADPTraining Thanks for the respond. I had few SES light. the noise is lessen due to cold temperature in new york. and the ses code is p0021 which is timing advanced problem. i paid nissan dealer for a diagnostic and they say there is -15degree off when it should be at +5 degree. i am not sure what parts in the engine they are talking about. due to some wearing inside. and they recommend replacing time chain, slave, belt and stuff like that. of course the quote was insanely high.

[shades2]

How long have knock sensors been around?

[51dumbdumb]

great vid but would we get a real person next time?

[arubin22]

Do you know where the knock sensor is on my 2000 Toyota Camry by any chance?

[ADPTraining]

@arubin22 Knock sensor is always screwed to the engine block. The knock is a microphone tuned to the engine ping frequency. Do a google on it. It may be in the V valley on a V-6 engine or at the side of the engine block on a 4 bangger...

[JrPilk]

I just got my engine code read. the codes were po327 and po332 for bank 1 and bank 2. Mechanic said it was the sensor that is for when the engine is knocking. Truck is fine and has been driving just came on one day doing some everyday driving. Light hasnt come back on so far. Is it just a bad sensor? wireing? Any help would be great thanks!

[flamingaxe791]

Dawm the Japanese are not human, how can they think of this stuff?!?

[unknownally]

Would be better with human narration IMO. Great video, though.

[sasop117]

tap the block with a spanner, its the engine revs decrease (ie its retarding it) the sensors is working

[xaIkyrie]

psh be happy its just the knock sensor. thats an easy fix. Im rebuilding my saturn motor. just wait, My car with be famous on youtube.

[slimshadie1290]

so im cutting out at 3500rpm. could it be my knock sensor?

[ADPTraining]

@slimshadie1290 No, to this day there're no engine management systems that'll make the engine cut out due to a know sensor. There are cases where a shorted knock sensor wire can make the engine stall, usually on older vehicles. Check your knock sensor wire for corrosion or bare damage. Good luck.

[bertito43]

@slimshadie1290 No, from experience it may be that your MAF (mass air flow) sensor is bad. Try cleaning it or replacing it and it will probably fix it.

[lillen300]

Wonder what my engine ping is XD 18milliseconds? XD HAHA

[FarceTheory]

I think I'll just stick with my four barrels and my MFI vehicles!

[treneale1976]

VERY HELPFUL VIDEO...NOW I JUST NEED TO FIND THE "KNOCK SENSOR" ON MY '98 EXPEDITION...=) TRE'

[ADPTraining]

@treneale1976 The knock sensor is always bolted to the engine block. Good luck.

[electricshockproof]

@ADPTraining That's not true.

[Polatron1]

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[The300ZXGuru]

just get rid of the sensor all together with a resistor.

[loots66]

pretty good info..

[wootness3000]

Sounds like one more sensor to break and cost $1K-US to fix.

[Turbotrip]

Appeared first time in the early 80s, when saab presented the APC system, to adjust turbo charge pressure. Now it is also used with ordinay ignition. Since the mid 90s saab has used the spark-plugs to determine ignition.

[changling21]

J & S safeguard knock sensor detects spark knock and adjusts the timing on an individual cylinder basis.