Not with HPTuners or anything. What would happen if the knock sensor was simply unplugged? Would the car go into limp mode or advance timing without any regard for knock?
I would guess CEL and limp mode
And i think you'd get a few melted pistons as a christmas present
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Generally if the ecm / pcm determines the knock sensor isn't functioning it will use a low octane spark table or use a preset maximum spark value which is very conservative. IOW no power. It will also set a trouble code. If you want to play this potentially dangerous game you're better off getting a resistor of the same value as the knock sensor and connecting it to the knock sensor lines. It still may not work but it will at least fool the pcm electrically.
-->Slow
hahahaha good way to cure your false knock
let's hope its just false knock, maybe we can find out more this weekend
is there any way to determine if there is false knock
DRIVE HARD OR DONT DRIVE AT ALL!!!
CAVI.DEMON wrote:is there any way to determine if there is false knock
Do what your sig says: DRIVE HARD OR DONT DRIVE AT ALL!!! If it blows, it's real, if not, it's false.
Well you DO have that set of pistons i traded you to go in there
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BTW this is ZxAlucard6r
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is there any way to determine if there is false knock
Yes, if you have hptuners you can use histograms to read your knock in much greater detail. They will tell you if the knock you are seeing is actually appearing long enough to register or not. I actually have disabled the knock correction on my car when racing it because the sensor is too sensitive. I do no recommend doing this as it's always nice to have the protection but I was running meth injection and race gas and knew exactly what my AFR's were. Hope that helps
"Horsepower is the Ultimate Accessory"
i have hp tuners but sometimes my afr is realy good and it will show like 6* of knock retard
DRIVE HARD OR DONT DRIVE AT ALL!!!
I believe it will pop on the CEL and you go to limp mode.
But I think also if you take a 10k (i think 10k, not exactly sure) ohm resistor, and put in the line and ground it, the ECU will believe that there's a KS present. This will cost you less than a dollar at radio shack.
guranted limp. Ive seen the computers on these cars go into limp for things far less serious then knock. that sensor is to important, to just ignore, and would take everyprecatuion to keep from seeing any knock at all.
"
boobs now with Riboflabin"
On the F-body's and vettes it runs on the LO table and applies full PE-KR (only -4deg in PE) as soon as the car goes into PE.
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guranted limp. Ive seen the computers on these cars go into limp for things far less serious then knock
Prolly want to get a better idea of what limp mode really is before deciding this.
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that sensor is to important, to just ignore, and would take everyprecatuion to keep from seeing any knock at all.
Yep. I'm with you. But I've worked on some engines which simply make too much mechanical noise to use a knock sensor effectively.
-->Slow
its a good thing you didnt just jump to the conclusion that I dont know what im talking about before you went ahead and hit enter.......oh wait....
limp is basicly the computers equivelent to us loosing one of our sens's if we lost our sight we be in no way confiedent moving around in a room, we would take are time and slow down.
when the pcm looses its knock sensor its basicly loosing the abilty to see detination. there fore its going to throw the timing out the door and baicly run the weakest timing advance possiable. plus its going to use its control over the injectors to dump fuel.
oh and that comment about the knock sensor. knock sensors work off a specific frequency, that is predetermined by enginers to detenation. each sound of the engine gives of a specifc frequency, and detition is no different. it is very possiable to put a knock sensor on any car as long as the frequency doesnt interfer with the other sounds of the engine.
hey, nice try though.
"
boobs now with Riboflabin"
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its a good thing you didnt just jump to the conclusion that I dont know what im talking about before you went ahead and hit enter.......oh wait....
I didn't jump to a conclusion. I said you should learn what limp mode is before deciding when the pcm will use it.
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limp is basicly the computers equivelent to us loosing one of our sens's if we lost our sight we be in no way confiedent moving around in a room, we would take are time and slow down.
That's your definition of limp mode, not GM's. Here's an exact quote from a GM training manual:
"[Fuel Backup Mode] is used only when the computer cannot operate normally and is sometimes referred to as the limp-home mode. The computer goes into Fuel Backup Mode if any one, or a combination of the following conditions exists: Computer voltage is below 9V, Cranking voltage is below 9V, PROM is missing or not functioning, pcm circuits fail to issue Computer Operation Pulses."
OBDII cars often don't even have a limp mode! No kidding. EPA says OBDII vehicles must be able to operate within emissions requirements if a single sensor fails. PCM will use a conservative timing map if the ks is bad, but it will not resort to dumping fuel. It's illegal and there's no need to anyway.
KS can be triggered by anything producing sounds. The sensor is tuned to be most sensitive to vibrations of the correct frequency, but it's not deaf to all others. Additional filtering helps narrow down and remove false knock, but it's not foolproof. Try tapping the block with a hammer while watching scantool... pcm will usually pull timing. Some forged pistons and some short skirt pistons make similar noise. High lift cams with roller lifters and roller rockers can be very noisy. Some clutches can make noise. The wrong combination of parts can create an engine which always triggers the ks.
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hey, nice try though.
Hey, you seem to be a pretty smart guy. Seemed like you might want the real story from someone with a *few* years of good experience and factory training. Guess I'm wrong.
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[Fuel Backup Mode] is used only when the computer cannot operate normally and is sometimes referred to as the limp-home mode. The computer goes into Fuel Backup Mode if any one, or a combination of the following conditions exists: Computer voltage is below 9V, Cranking voltage is below 9V, PROM is missing or not functioning, pcm circuits fail to issue Computer Operation Pulses."
OBDII cars often don't even have a limp mode! No kidding. EPA says OBDII vehicles must be able to operate within emissions requirements if a single sensor fails. PCM will use a conservative timing map if the ks is bad, but it will not resort to dumping fuel. It's illegal and there's no need to anyway.
we baiscly just agreed acept for the fact that, if the pcm loses a sensor that potenially has conrtol over fuel, say for instance the IAT, then its going to reset to a much more genorus fuel map, trusssst me on this one, Ive maxed out the voltage on a wideband and watched my car fall flat on its face at idle when I forgot to hook my iat up.
I dont think it just clips out the injectors and throws fuel, but I can gurantee its in no way a stoich burn.
as for knock. theyv gotten very good at relviign phantom knock. and the old slap a wrench on the knock sensor trick doesnt work anymore. it can tell now on most cars. yes there not def to other sounds, but there getting there.
"
boobs now with Riboflabin"
... care full, you dont want to piss off some one that really knows what hes talking about......
hes the one that is doing it, not some E-thug that is on-line typing it...... his old purple car could rap your all mitey ECO.
I'm my experience with GM,99 percent of the time, if SI, or the GM service manual says that "X" happens because "a" has happened, it does.
but your young, you know it all! right?
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
