So today I was under my car and i tried this out. I unbolted the knock sensor and cut a rubber hose that fits around the bolt snug into 2 - 1/4 inch peices. then i took and put them on both sides of the knock sensor like washers 1 between the sensor and block and one between the sensor and the head of the bolt. then I just tightened the bolt back onto the block. This worked great. It desensitized it enough so I wasn't getting a rediculous amount of timing retard. Try it.......
Hmmm.I think that putting a 75 or 100 ohm resistor in line with the knock sensor would be safer.At least the sensor would still work if there was hard detonation.
Thats Him Officer The WICKED One.
[sarcasm] It would be a good idea to take out your radiator too, no sense in having it take up so much space/weight, the same applies to your oil pump [/sarcasm]
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But it does still work because the bolt is still in contact with the metal sleeve in the knock sensor.
Guys with LS1's who have large cams + exhaust do this all the time. On heavily modified engines, extra vibrations and noise can be interpreted as "knock" by the engine causing excessive timing retard. Many claim this is dampening the computer's ability to sense real knock, but in actuality it's just helping to filter out extra noise/vibration. This helps minimize timing retard resulting from false knock detection. Just don't desensitize the sensor too much and you'll still be safe.
i would never touch my knock sensor... after seeing what even the slightest knock can do to an boosted engine.....
The First Twin Charged jbody
blue car (R.I.P) - 240whp @7psi..
silver car - 305whp 315lbs.tq @15psi (91 Octane) or 420whp & 425lbs.TQ @20psi (94 octane+Alcohol Injection)
All dynos run on a Mustang dyno
Nickobub wrote:Guys with LS1's who have large cams + exhaust do this all the time. On heavily modified engines, extra vibrations and noise can be interpreted as "knock" by the engine causing excessive timing retard. Many claim this is dampening the computer's ability to sense real knock, but in actuality it's just helping to filter out extra noise/vibration. This helps minimize timing retard resulting from false knock detection. Just don't desensitize the sensor too much and you'll still be safe.
this is sooo true. Some people on here at like this should never be done. At the same time this is not for anyone and everyone. This should be done very carefully. People who have had the tranny mount inserts have had problems with too much vibes causing knock retard, when there was no real knock.
Let me ask this. If you are getting knock retard, but you have had it checked out, and there is no real knock, should you just live with it? Live with the lose of power do to vibes, noise etc??
FU Tuning
considering the knock sensor gets its reading from the base of the knock sensor , and not the bolt
i doubt anyone here here has even checked it both ways to see what is causing the knock
even with stock mounts you should see activity on the knock sensor
just cause something works doesnt mean its the right thing to do
[quote=97cavie24ls(JDM&00s/c sedans™)]considering the knock sensor gets its reading from the base of the knock sensor , and not the bolt
i doubt anyone here here has even checked it both ways to see what is causing the knock
even with stock mounts you should see activity on the knock sensor
just cause something works doesnt mean its the right thing to do
I understand what you are saying abotu the readings coming from the base, but the connections itself (bolt, screw, whatever you want to call it) had to transfer the possible knock to the base.
In this post I can not say if anyone has check both ways. In the past there was a long post about phatom knock due to the tranny mounts. Andrew was one of the guys involved. he had a lot of research in regards to this. He knew his was not real knock.
Your comment about the stock mounts and activity is right on, that even proves my point more. Stock mounts allow some vibes and some knock retard, so what are the stiff mounts (all the mounts together, engine, tranny etc) going to do??? Truthfuly in theroy adding mounts could hurt performance, not help.
You are also right just because something works does not mean you should do it. Gopes the same for any of the mods we do, as well as just because the knock sensor stock works does not mean it is right, and we should go by it.
FU Tuning
if i remember the 99-02 knock sensor the top is plasctic where the bolt holds it down , and the bolt is smaller than the hole in the knock sensor , the base of the sensor is metal
i do remember alot of people back in the 80's and early 90's doing this to help prevent the knock retard , if you look in the service manual for the TQ spec , the knock has a specific tq # , and what they used to do was tq the knock sensor at a lower value , which changed the sensitivity value for the knock sensor , this is on the older knock sensor
now the same thing should happen for the newer 1
putting some between the 2 surfaces will block out all that information
also i wouldnt put the blame on the trans mounts , i would say all are resposible
my g/fs eco cav , actually had less vibration with the trans mounts added then with out the trans mounts
but for someone to just do something to the knock sensor with out doing everthing else to prevent the problem is WRONG
also each car will be different , so what works on 1 car might not work as good , if even at all on another , so each one needs to do his own check and find out what is causing the knock retard whether it is phantom or actual knock , then to find out what to do to correct the problem
and not go by what 1 person says worked on his car with no testing on his specific car
[quote=97cavie24ls(JDM&00s/c sedans™)]if i remember the 99-02 knock sensor the top is plasctic where the bolt holds it down , and the bolt is smaller than the hole in the knock sensor , the base of the sensor is metal
i do remember alot of people back in the 80's and early 90's doing this to help prevent the knock retard , if you look in the service manual for the TQ spec , the knock has a specific tq # , and what they used to do was tq the knock sensor at a lower value , which changed the sensitivity value for the knock sensor , this is on the older knock sensor
now the same thing should happen for the newer 1
putting some between the 2 surfaces will block out all that information
also i wouldnt put the blame on the trans mounts , i would say all are resposible
my g/fs eco cav , actually had less vibration with the trans mounts added then with out the trans mounts
but for someone to just do something to the knock sensor with out doing everthing else to prevent the problem is WRONG
also each car will be different , so what works on 1 car might not work as good , if even at all on another , so each one needs to do his own check and find out what is causing the knock retard whether it is phantom or actual knock , then to find out what to do to correct the problem
and not go by what 1 person says worked on his car with no testing on his specific car
I totally agree that it might work on my car (never done it, just saying), but might not work on your car. In case of a boosted car there is amny things that should looked at before doing this. But if the research is done then it could be worth doing.
Also you are correct the newer knock sensor has a bolt going through it. The Pre- 2000, or pre-99 knock sensor, are just like the older V8 ones. A complete unit and screws into the block. I will say trying to lossen it up some might be a better option than putting stuff in it, or around it.
FU Tuning
There is no way I was getting true knock readings from the sensor. I am running alcohol injection and the best grade of gas I can buy. I do get alot of vibes due to mounts and the friggan noise from the stupid getrag transmission and the exhaust not having any flex pipe. If it was real knock it would do it more when it is hot out. I was having problems more when its cold out.
DCStang67 wrote:There is no way I was getting true knock readings from the sensor. I am running alcohol injection and the best grade of gas I can buy. I do get alot of vibes due to mounts and the friggan noise from the stupid getrag transmission and the exhaust not having any flex pipe. If it was real knock it would do it more when it is hot out. I was having problems more when its cold out.
Hmm, careful...cold air can lead to a leaner AF mixture from greatly improved air density, and thus enhance detonation. More engines have been damaged due to inadequate cold-air tuning than due to hot-weather induced knock.
Guys, this concept of adding a resistor to the knock sensor intriques me. On the surface, it seems odd to me, as the sensor itself is a piezoelectronic component, and emits a frequency signal when engine vibration resonance reaches a certain frequency, as opposed to a simple variable voltage. Can anyone shed more light on this? I do like the idea of following what the V8 crowd does...its all the same hardware, and almost the same software.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
DCStang67 wrote:There is no way I was getting true knock readings from the sensor. I am running alcohol injection and the best grade of gas I can buy. I do get alot of vibes due to mounts and the friggan noise from the stupid getrag transmission and the exhaust not having any flex pipe. If it was real knock it would do it more when it is hot out. I was having problems more when its cold out.
how do you know ??? cause it seams more like your pulling everything out of the air !!!!!
i know when i had 101 octane race gas in my car my knock retard was lucky if it went over 1 if it even showed any readings at all
with 1/4 tank 101 , and 3/4 tank of 91 my readings have gone alot higher , which tells me most of my spark knock is TRUE detonation , not phantom knock
ive got upper and lower mount , no trans mount (dam auto) , and at idle my car vibrates worse than a milwaukee vibrator , and its alot worse with the a/c on
so with out you doing any real testing to isolate your knock retard problem , your as retarded as your problem is
and when your motor blows , ill be 1 of the FIRST to laugh my ass off at you !!!!!!!!!!
i hate to sound like a ass about it , but with out reaserch on each individual case , you dont know jack , and someone will dumber by listing to you , untill you do your research
yea... knock sensors are your friend, regardless of what fuel you are running. it's like wearing a condom, but poking holes in the tip of it...
I was a retard, and now I'm permanently banned.
Ill let you know when it blows up. And when it does ill just rebuild it to handle all the boost I can give it, because I have the money and the knowledge to do all the work myself.
DCStang67 wrote:Ill let you know when it blows up. And when it does ill just rebuild it to handle all the boost I can give it, because I have the money and the knowledge to do all the work myself.
COOL , ill be waiting
but i think you should still research the issue on your car , and then find the correct way to cure the issue
its alot better than trying to band aide the issue
Bill Hahn Jr. wrote:DCStang67 wrote:There is no way I was getting true knock readings from the sensor. I am running alcohol injection and the best grade of gas I can buy. I do get alot of vibes due to mounts and the friggan noise from the stupid getrag transmission and the exhaust not having any flex pipe. If it was real knock it would do it more when it is hot out. I was having problems more when its cold out.
Hmm, careful...cold air can lead to a leaner AF mixture from greatly improved air density, and thus enhance detonation. More engines have been damaged due to inadequate cold-air tuning than due to hot-weather induced knock.
Guys, this concept of adding a resistor to the knock sensor intriques me. On the surface, it seems odd to me, as the sensor itself is a piezoelectronic component, and emits a frequency signal when engine vibration resonance reaches a certain frequency, as opposed to a simple variable voltage. Can anyone shed more light on this? I do like the idea of following what the V8 crowd does...its all the same hardware, and almost the same software.
Bill I'm glad you have read this post. I was wanting your imput on this as well. Now I agree every car and set-up is diferent. SO can we get some imput from a well tuned car. What kind of knock readings if any do you guys get? Also since you guys have worked with many cars other that a GM do you know, ro can you get info on what kind of knock count any of youor others cars have had?
Also do we know if the Ecotec has the same knock sensor, or at least style as the 2000+ 2.4's?
FU Tuning
Also Bill can you explain more what you were stating about a leaner condition with cooler air? I will admit I do not know all about tuning. I just always thought if you are running cool air, not as much fuel will be needed to keep the same A/F ratio. For instance taking a non-intercooled car and then intercooling it. You are dropping the intake temps. I would think not as much fuel would be needed (as there would be with it non-intercooled).
FU Tuning
the more dense the air is the more oxygen is in the air , the more oxygen in the air per cubic foot
means the air into the motor is getting more oxygen , meaning it leans the motor out
the hotter the air is the less dense it is meaning , there is less oxygem per cubic foot , which tends to richen the mixture
the 99-02 2.4 and the 02-05 eco use the same 2 wire knock sensor , the 98-older 2.4 , and the ohv's use the larger 1 wire knock sensor
im not sure if the part #s are the same or not
i do know GM used several different knock sensors with the 98 - older style , depending on the motor , even though the look identical , the signal they give is the same , but the frequency that excites them is different for each type motor
and bill , it was either chevy high performance , or gm high performance mag that had the article about it
*blows whistle* OK, troops, let's stay on topic here...take it outside!
lol, I always fantasized about being a drill sargeant...
We keep the knock demon in contol on our Eco Sunfire via three things: correct fueling that's a tad rich, 100 octane (which is why we keep it a tad rich, it's not 110), and slightly lower compression than stock.
Our knock sensor is in stock condition. It's the Bosch style unit that is concentric around its attaching bolt. I am glad GM went to this style sensor...it seems to be the most effective design. I don't know if your 2.4 uses this or not.
Admittedly, we are not logging timing advance or knock sensor activity, so I don't have any real hard data about same to share. However, the car's been so consistent that I've really not had to find things like this to study in more detail...I am presuming we have no problem.
Instinct tells me that the relative resonance of an aluminum block is considerably different than iron. Aluminum is 'deader' and less resonant than iron, which may make the Ecotec more forgiving to types of external noise and vibration that could upset an iron block's knock sensing system. We have filled mounts on the trans, an RKSport lower link on engine (still urethane bushings), and a stock upper engine mount. Solid metal mounts are for race cars only, and are to be avoided for many reasons...this knock sensing aspect being just one.
Additionally, we've removed our balance shafts, and are running JE 'mini-skirt' pistons that are very, umm, LOUD until fully warmed up. So, ours may well be a worst-case scenario as far as a car that might trip off the knock sensor when it shouldn't...and I think we are doing fine.
I know that the engineers who set these knock control systems up pay very close attention to the particular 'noise' signature of the engine, and 'tune' the knock sensor system accordingly. Bear in mind, detonation is a quite specific sound to these sensors...like anything that's expressed in frequency, the possibilities are almost endless. Thus, the sensor systems may not be as 'stupid' about other noises/vibrations as you may have been led to believe. Ever see how many bandwidths are available just in the entire radio spectrum? Or broadband? The numbers are huge! Ever think about how they get both internet and 500 freeking cable channels on a single wire coming into your house? It's all about frequency and equipment that can discern the different wavelengths. Mind you, comparing engine noises to communications frequencies is a broad illustration, but it gives you a comparative idea.
In some cases, to avoid inaccurate readings, the engneers design so the sensor's output is only looked at during certain crankshaft positions when knock would be happening, thus automatically ignoring any other 'noise'. The sensor that came on your engine is attuned to the engines behavior...swapping with sensors from different type engines may not effective.
I've also worked with 'add-on' knock sensing systems that were a bear to make work well for all of these reasons. The systems were too simple, and the sensors used too general. We decided such 'add-ons' were not viable, but also came to respect the engineering that the factory systems demonstrated in comparison.
I will post later about the AF ratio questions and offer some advice on how to tell if one's knock-sensor system is indeed misbehaving.
And if anyone can offere more on the 'resistor' trick, or anything at all about this subject, please add to the convo. GM-specific info you may have is especially appreciated.
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
[quote=97cavie24ls(JDM&00s/c sedans™)]and bill , it was either chevy high performance , or gm high performance mag that had the article about it
If you are referring to the article about the RK car, it was in Chevy High mag. I really enjoyed working with the fellow who dyno-tuned the car, but I felt he was chasing shadows in many areas, the knock sensor and MAP sensor being two of them. He devised ways to make mods there that I found to be, well, confusing and/or excessive! Not to say he didn't have valid points, but my experience with this Ecotec engine management is fairly extensive, and the mods he stated were required are just not.
The car in question had a long history of being blown-up due to nitrous (before our turbosystem was installed!), and what seemed to be inadequate engine prep. I'd wished they'd have just put a stock Eco in it and ran with that with the turbosystem! All this is happening 2000 miles away, so my ability to assist was very limited, as well as my ability to not become the easy fall-guy (it's hard to defend your product on a project that's just gone to crap if you're not there to keep everyone on the right track)...By the time they got around to putting our turbosystem on it, I think everyone involved was gun shy as could be! Perhaps this is why the tuner felt compelled to go so deep into mods I found to be largely unneccesary.
The fun part was explaining all this to the magazine editor at the project's end without portraying the tuner as a schmo. I think we came to an equitable conclusion, but it hurts when you give up $3500 worth of proven product in exchange for some good editorial coverage, and then the 'experts' chosen proceed to cut it up like a Ginsu chef. Not exactly the outcome I was looking for, but so it goes with mag coverage...its not always a slam-dunk.
Is there any info out there which corroborates this 'resistor into the knock-sensor circuit' trick? Or was my tuner friend just playing Radio Shack on us?
Bill Hahn Jr.
Hahn RaceCraft
World's Quickest and Fastest Street J-Bodies
Turbocharging GM FWD's since 1988
www.turbosystem.com
