GM knock sensor thread Options

[lagos]

shouldn't the GM sensor be just fine considering it was tested at 5700 and the Toyota one was tested at 6300??

what part of narrow band sensor dont you understand? narrow band means that its only tuned to pick up that one specific frequency. this is done so that the sensor will only pick up knock at the correct frequency and ignore any false alarms. if you agree that the sensors are not the same frequency, then you should know why its bad to use one.

I bought the GM knock sensor conversion so that if I DID encounted knock suddenly and violently, I wouldn't be stuck paying $150 for a new knock sensor.

if you encounter massive knock .... it dosnt mean your sensor will blow. i got severe detonation on the dyno (with a dyno chart to prove it) and my knock sensor did its job and still works great since 1990.

the ats kit costs about 80$ . a new OEM sensor from toyota sells for 124.27$. seeing as how its a vital part of the motor, this is not where i would cut my budget and try to save 40bucks

Yes, I am using the GM knock sensor because I know that it's harder to blow. Think about this: You're running the car hard without a datalogger. You start to get knock that you can't hear audibally, and it's working as advertised. Then the OEM one blows and before you have a chance to react (you're still in the gas) the knock continues and you pop a piston. I'd rather have the GM knock sensor in there with it's ability to take a bit more abuse than the OEM one.

you clearly dont know how the whole knock system works. if the GM sensor can take more abuse, then it means that there is more abuse happening inside of you motor that the sensor is not picking up. youll blow a piston before you blow the sensor if you use the GM one. if the knock sensor ever blows (they very rarely blow on a stock 3s) the ecu will know it right away and save the motor.


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now lets get down the the real issue here. drtweak talked you into all these upgrades and now is trying to fight tooth and nail so that he dosnt look like he made a bad call on something. thats all this is about. i mean, you have a million people on here trying to tell you how bad that sensor is, and only one person whos trying to play word games to try to justify keeping it. i dont know how you can ignore the advice of people who have daily driven, dynoed, tracked, and raced their swaped cars for years.

[Fastbird]

First things first, Dr. Tweak did NOT talk me into all these mods. Specifically speaking, the knock sensor conversion was MY idea. So please leave the assumption that he's fighting over this to cover his own rear out because that is completely wrong.

Blowing the sensor will not alow you to continue knocking. It is a safety feature built into the Toyota ECU. If you have knock severe enough to blow your sensor there is obviously something wrong and it puts the car into low boost mode. That is, if you still have your T-VSV connected. If not you should at least have it wired to a light so you know when it's being activated by the ECU. Again, all of this is covered in the post that Jay linked to at MR2OC.

Ok, THAT I did not know. I was not aware that Toyota had a safety feature built into the ECM to protect the car with loss of the knock sensor. Lagos though, to say that I completely do not understand knock systems is a bit pre-emptive. I may not know everything, but I think it's pretty clear that I have a certain understanding of what they're for and what they do and how they interact with the ECM.

Have a look at what John @ J&S had to say in a post in the talked about thread on 2 Sept 2004 since everyone is so up tight about that one post which is pushing almost over 2 years old at this point.

You guys are making way too big a deal out of this.

A few years ago, a GM knock sensor guy sent me a list of the most commonly used sensors. At the time, they were only making them in three frequencies to cover all their engines. The frequencies were 5.2 kHz, 6.0 kHz, and 7.0 kHz.

They call their sensors "broadband resonant", and they will respond over a kHz or so bandwidth.

GM chose broadband sensors for a number of reasons. The knock frequency can increase a few hundred Hz with an increase in combustion temperatue, so the bandwidth of the sensor must be wide enough to allow for that. Also, broadband sensors will cover for normal manufacturing tolerances of the engine, and, because they will work on more engines, they don't need to stock as many part numbers.

Right there is what I was talking about. They respond over a variety of frequencies, not just a single pre-programmed frequency.

I just had a look around MR2 OC and other than that one thread and a couple of people saying don't use it, there's several more over there that are promoting it and having no issues.

I noticed that no one had anything to say about my comments about the changing frequencies at which knock will register based on the position of the piston in the cylinder???

This post has been edited by Fastbird: Jul 12, 2006 - 12:55 PM

[Consynx]

don't almost all sensors go into a safe mode when the sensor doesn't reply back to the ecu without a voltage reading?

cars have come a LONG way.

also, gotta use that frequency completely
it covers a RANGE, but the range depends on the type of sensors and such.

and since engine resonancies can chance easily, i'd just stick with what there is.

or if you got money, just find a way to bypass the knock sensor completely and run 103 octane all the time

This post has been edited by Consynx: Jul 12, 2006 - 12:38 PM

[Fastbird]

And another thing . If GM sensors are narrow band sensors, then why can I loosen my valve lash and create knock that gets picked up by the sensor??? Why can I swap from a stamped steel rocker to a full self aligning roller rocker and get knock?? Why can I have a long tube header merge collector tapping on a crossmember and cauing the knock sensor to do it's thing?? Why do you have to completely disable the knock system when converting to a solid roller valvetrain? You can't possible say that the knock sensor will only pick up on a single frequency based on the bore of the block when so many outside the bore items will set it off.

Look at this. Where does the knock sensor install?? I don't know for sure about the 3S-GTE, but on ALL GM motors the knock sensor installs into a water jacket. WHY?? Because the knock sensor pickup will be always submerged in the coolant which makes an excellent transmitter for various knocks that occur within the motor. Hence, I don't see HOW the knock sensor can only pick up on a single tuned frequency. Support for this again is shown in the above paragraph.

You guys are starting to beat a dead horse with this. You're not going to change my or Doc's opinion on this. It's my motor, I'll do what I want. I took your advice with due regard, and made what I feel is an educated decision based on what I've seen from testing and real world use. Fact of the matter is that I'm sticking with the GM knock sensor because I feel that it's an adequate alternative to the overly priced OEM Toyota knock sensors, and that decision isn't going to be swayed. I know that you guys are watching out for me with what you feel is the best thing, and I sincerely appreciate that.

That said, if my motor ever grenades due to the gm knock sensor not doing it's job, I'll sponsor a meet or something (food, beverage, coordination, ect) and publicly admit I was wrong.

[jgreening]

That is one post in the thread. And if I were willing to ignor Ricky B and the testing by 510Rob, it might be enough for me to say maybe getting a knock sensor for a different frequency would be a suitable alternative.

As for your question, if stroke does not matter to knock frequency, piston position should not matter either. Even if it did, knock is pre-ignition due to the charge occuring due to compression. I would assume (I dont know this for sure) but that the piston position of detonation is within a relatively small range since that compression will occur as the piston travels toward TDC.

I know both you and Manny may have been offended by the statements "its your motor" and "see how much you save if you have to replace a blown motor" but I was not. These statements are designed to make you think if you are being penny wise and dollar foolish.

One thing to remember, we all made mistakes in our build. Why? Because during the process of the build (and afterward), we learned things that would cause us to do it differently if we did it again. I actually started a thread awhile back about things I would do differently if I were swapping today rather than two years ago for people who are in your exact position. Bottom line: its not a bad thing to have your plans critiqued by others who have been there and then change courses. We cannot possibly know all of this stuff before going through it. I wish you the best of luck.

[Fastbird]

don't almost all sensors go into a safe mode when the sensor doesn't reply back to the ecu without a voltage reading?

I would think so. I know my T/A ran like crapola when my knock sensor popped on me. But I wasn't aware that toyota had built in a way to limit boost output at the same time. Neat trick there.

[presure2]

Look at this. Where does the knock sensor install?? I don't know for sure about the 3S-GTE,

that would be on the back of the block, behind cylinder #1
knock sensor replacement, even with the engine installed, should take no more than 5 minutes with a decent jack.

[Fastbird]

That is one post in the thread. And if I were willing to ignor Ricky B and the testing by 510Rob, it might be enough for me to say maybe getting a knock sensor for a different frequency would be a suitable alternative.

As for your question, if stroke does not matter to knock frequency, piston position should not matter either. Even if it did, knock is pre-ignition due to the charge occuring due to compression. I would assume (I dont know this for sure) but that the piston position of detonation is within a relatively small range since that compression will occur as the piston travels toward TDC.

I know both you and Manny may have been offended by the statements "its your motor" and "see how much you save if you have to replace a blown motor" but I was not. These statements are designed to make you think if you are being penny wise and dollar foolish.

One thing to remember, we all made mistakes in our build. Why? Because during the process of the build (and afterward), we learned things that would cause us to do it differently if we did it again. I actually started a thread awhile back about things I would do differently if I were swapping today rather than two years ago for people who are in your exact position. Bottom line: its not a bad thing to have your plans critiqued by others who have been there and then change courses. We cannot possibly know all of this stuff before going through it. I wish you the best of luck.

Good words man. I'll clear up that I wasn't offended by the statements, just getting sick of them.

As for piston position in the cylinder, taking an LT1 as example, that's a stock 3.48" stroke. That's 3.48" where the piston could be located anywhere in that cylinder. If you're talking about a 4.00 bore, then you're looking at a volume change of approximately 43.75 cubic inches or .7125L on that cylinder between TDC and BDC. If there is a condition that's severe enough, you could possibly even detonate prior to the intake valve closing before the compression stroke has even begun (ever see a V8 with a couple of swapped plug wires). Given that, I feel that there's going to be a marked frequency change in the knock between the two points (TDC and BDC) with the volume change. I know it's not a 3S-GTE but the same theories still apply as a motor is a motor for the most part.

[jgreening]

You guys are starting to beat a dead horse with this. You're not going to change my or Doc's opinion on this. It's my motor, I'll do what I want. I took your advice with due regard, and made what I feel is an educated decision based on what I've seen from testing and real world use. Fact of the matter is that I'm sticking with the GM knock sensor because I feel that it's an adequate alternative to the overly priced OEM Toyota knock sensors, and that decision isn't going to be swayed. I know that you guys are watching out for me with what you feel is the best thing, and I sincerely appreciate that.

Please understand that some of our persistence is to make sure that misinformation is not perpetuated. I am now confident that someone finding this thread in the future can make an educated decision based on the information contained here.

[Fastbird]

Look at this. Where does the knock sensor install?? I don't know for sure about the 3S-GTE,

that would be on the back of the block, behind cylinder #1

Is that into a water jacket?? I.E. does coolant come out when removed?? I seriously don't know on the GTE but would like to.

[Dr_Tweak]

You know what you guys should do, if you really want to pursue this? Start a poll, where people put if they have the stock sensor or the GM sensor, and of those that have the GM sensor, how many have blown their engines.

If I saw a good number of people have actually blown their engines because of using the GM knock sensor, then I would change my mind on this subject.

-Doc

[Fastbird]

Please understand that some of our persistence is to make sure that misinformation is not perpetuated. I am now confident that someone finding this thread in the future can make an educated decision based on the information contained here.

That's what these forums are for, right?? I'll pony up and be the classic example once in a while.

[Dr_Tweak]

Look at this. Where does the knock sensor install?? I don't know for sure about the 3S-GTE,

that would be on the back of the block, behind cylinder #1

Is that into a water jacket?? I.E. does coolant come out when removed?? I seriously don't know on the GTE but would like to.

Nope.

[Consynx]

that was smart of GM to put it in the coolant actually...sound travels faster that way
just don't know if any kind of flow pattern of the water would actually dampen the noise :\

[CilverSeliST205]

When there's people running a GM sensor without issue (just because some people have issues doesn't mean all will) when it costs $25 and then those that insist on paying $150 for a OEM one, who's the stupid one there?

Then the OEM one blows and before you have a chance to react (you're still in the gas) the knock continues and you pop a piston. I'd rather have the GM knock sensor in there with it's ability to take a bit more abuse than the OEM one.

To Art, Manny, Jay:
Because GM sensor is harder to blow does not mean that it doesnt pick up all the knock thats occuring, it might be more sturdy thats all. It is not proof that it will ignore/not respond to certain knock frequency.

To Fastbird and Tweak:
I think that blowing a toyota KS prevents critical motor failure more so than retarding timing by unblown GM KS. By settling for a lower safety level you endanger your engine more. It is not at all good way to save money.

If you dont want toyota sensor because its too expensive to replace, dont settle for GM because it works (how well it works is still unknown)... Get J&S or MSD knock monitor.

[Fastbird]

Look at this. Where does the knock sensor install?? I don't know for sure about the 3S-GTE,

that would be on the back of the block, behind cylinder #1

Is that into a water jacket?? I.E. does coolant come out when removed?? I seriously don't know on the GTE but would like to.

Nope.

Huh......interesting. Learn something new every day.

If you dont want toyota sensor because its too expensive to replace, dont settle for GM because it works (how well it works is still unknown)... Get J&S or MSD knock monitor.

Ummmm.......I thought it was stated that the J&S and MSD both used the GM knock sensor.

[Consynx]

Good words man. I'll clear up that I wasn't offended by the statements, just getting sick of them.

As for piston position in the cylinder, taking an LT1 as example, that's a stock 3.48" stroke. That's 3.48" where the piston could be located anywhere in that cylinder. If you're talking about a 4.00 bore, then you're looking at a volume change of approximately 43.75 cubic inches or .7125L on that cylinder between TDC and BDC. If there is a condition that's severe enough, you could possibly even detonate prior to the intake valve closing before the compression stroke has even begun (ever see a V8 with a couple of swapped plug wires). Given that, I feel that there's going to be a marked frequency change in the knock between the two points (TDC and BDC) with the volume change. I know it's not a 3S-GTE but the same theories still apply as a motor is a motor for the most part.

?
not quite sure what you're going for here, but i think you were just agreeing which is kewl.


also, J&S sells some kit which uses a wideband sensor and is very accurate, like $400?
it seems like it's just a piggyback sensor(semi-standalone? lol)

also, bringing a V8 in was prob a bad idea, since sensors are kept within families. although each engine is slightly different, going from a I4 to I6 would be bad. I don't think you were trying to compare the 8 to the 4 though...i just can't deal with reading all this stuff more than twice.

This post has been edited by Consynx: Jul 12, 2006 - 1:10 PM

[Fastbird]

Consynx, cliff notes was that I used how the cylinder volume changes with the stroke of the piston to represent how easily the frequency of the knock could change also.

I wasn't comparing the V8 directly to the I4, just pointed that an engine is an engine. I just used the V8 as an example because I know the bore and stroke and cylinder displacement right off the top of my head.

This post has been edited by Fastbird: Jul 12, 2006 - 1:13 PM

[lagos]

And another thing . If GM sensors are narrow band sensors, then why can I loosen my valve lash and create knock that gets picked up by the sensor??? Why can I swap from a stamped steel rocker to a full self aligning roller rocker and get knock?? Why can I have a long tube header merge collector tapping on a crossmember and cauing the knock sensor to do it's thing?? Why do you have to completely disable the knock system when converting to a solid roller valvetrain? You can't possible say that the knock sensor will only pick up on a single frequency based on the bore of the block when so many outside the bore items will set it off.

your are such a domestic guy...lol the 3s dosnt have rockers or long tube headers.

[CilverSeliST205]

Ummmm.......I thought it was stated that the J&S and MSD both used the GM knock sensor.

Im not talking about just the sensor. Both companies sell a device which, unlike 3sgte ecu, was ment to work with GM sensor. I believe that J&S retards timing through the device, not through the ECU. Another thing is that GM sensor being able to pick up different frequencies (being wideband) can interpret signals that ECU does not understand, unlike these "knock monitor" devices.