... Mine for instance pings only when climbing a hill in overdrive (i have the automatic transmission). It will only ping/detonate going between 50 and 60 mph when my truck is going fast enough up the hill that the transmission dosent need to downshift out of overdrive, but if i push hard enough on the throttle the transmission will think i want to accelerate and downshift out of overdrive, which will stop the ping/detonation when going up the hill.

That's kind of normal when your engine is loaded down going up hill in O/D. You can turn it Off manually or adjust the throttle cable so it downshifts sooner.

 

Sensors don't "do" anything - they just send signals to the ecu. It's the ecu that "does" stuff, based on signals received by various sensors. Yes, when the knock sensor sends pulses of current as a result of detonation, the computer is supposed to retard timing, but there are other factors that influence the ecu's decision, and conditions that can cause pinging to continue even after ignition is retarded.

Suggest reading the threads linked under the pinging and code 52 knock sensor sections in the links post of the massive truck info sticky. Lots of info in those threads that will answer many of your questions.

 

I have a 1990 toyota pickup 2wd 22re auto. Do I have a knock sensor??

 

Not sure, but probably not. For some bizarre reason, Toyota left them off of some or all of the 2WD 22RE models. You can look for it above and aft of the oil filter if it's there.

what does pinging sound like exactly?

Something like dropping a bunch of marbles on top of a heavy steel safe.

 

what does pinging sound like exactly?

 

Firstly, as a bit of technobabble, there are two kinds of pinging: detonation (somewhat OK) and pre-ignition (holy pistons batman!). Detonation is somewhat normal on an engine putting out a lot of power especially if it's in lower rpms (IE climbing a hill loaded w/o downshifting). Pre-ignition is sort of the extreme version of it. The difference is that detonation is a second flame front igniting AFTER the spark sets off the primary (remember gasoline isn't exploding in the combustion chamber, it's a controlled burn). Pre-ignition is when conditions are right that the mixture ignites before spark occurs. This causes a build up of pressure while the piston is still rising and is how you melt rings, blow holes in pistons or head gaskets, and generally destroy an engine.

Either one can be caused by high compression/low octane for the compression ratio, glowing carbon, etc. lean mixtures makes it more susceptible which is part of the reason cars run rich at WOT...just to be sure since there's so much noise the knock sensors not as reliable.

the knock sensor sends a voltage signal to the ECU and yes, the ECU pulls ignition timing: that's it.

I usually think of it as sounding like shaking a spray paint can after the paints all gone and the ball's just bouncing around.

As far as why some do and some don't, a lot of it has to do with lots of people not knowing what to listen for and some people calling loose valves or bearings pinging. also, as with any 20+ year old engine design, some have been rebuilt, some more than once. shaving the head and/or block will raise compression which increases the tendancy to ping. Could also be one injector running rich or another running lean throwing off the mixture for the others (lean running ones start to ping, others are OK). or differences in compression. Quality of gas will affect it too. running hot, EGR ports plugged, increased ignition timing all contribute.

 

Firstly, as a bit of technobabble, there are two kinds of pinging: detonation (somewhat OK) and pre-ignition (holy pistons batman!). Detonation is somewhat normal on an engine putting out a lot of power especially if it's in lower rpms (IE climbing a hill loaded w/o downshifting). Pre-ignition is sort of the extreme version of it. The difference is that detonation is a second flame front igniting AFTER the spark sets off the primary (remember gasoline isn't exploding in the combustion chamber, it's a controlled burn). Pre-ignition is when conditions are right that the mixture ignites before spark occurs. This causes a build up of pressure while the piston is still rising and is how you melt rings, blow holes in pistons or head gaskets, and generally destroy an engine.

Either one can be caused by high compression/low octane for the compression ratio, glowing carbon, etc. lean mixtures makes it more susceptible which is part of the reason cars run rich at WOT...just to be sure since there's so much noise the knock sensors not as reliable.

the knock sensor sends a voltage signal to the ECU and yes, the ECU pulls ignition timing: that's it.

I usually think of it as sounding like shaking a spray paint can after the paints all gone and the ball's just bouncing around.

As far as why some do and some don't, a lot of it has to do with lots of people not knowing what to listen for and some people calling loose valves or bearings pinging. also, as with any 20+ year old engine design, some have been rebuilt, some more than once. shaving the head and/or block will raise compression which increases the tendancy to ping. Could also be one injector running rich or another running lean throwing off the mixture for the others (lean running ones start to ping, others are OK). or differences in compression. Quality of gas will affect it too. running hot, EGR ports plugged, increased ignition timing all contribute.

Thanks for the post!!! So im guessing that my Knock Sensor is communicating properly with my ECU and that my ECU is reading the voltage of the knock sensor and retarding the timing as far as it can based on the readings of other engine signals without causing drivability issues.

 

^ Good posting :thumbsup: