Car knocks with Sensor unplugged
09-05-2008, 12:07 AM
#1
TECH Regular
Thread Starter
iTrader: (2)
Join Date: Feb 2004
Location: 1985
Posts: 426
Likes: 0
Received 0 Likes
on
0 Posts
Car knocks with Sensor unplugged Other than a wiring problem ( which isnt being seen ) is it possible for the car to see knock when the knock sensors are unplugged?
Have a turbo 99 z28 on a Maf tune that knocks at any throttle level as long as the MAP sensor sees above 90 Kpa . What am I missing - Tried changing the tune file to another 99 Turbo ls1 that runs fine, same problem.
Have a turbo 99 z28 on a Maf tune that knocks at any throttle level as long as the MAP sensor sees above 90 Kpa . What am I missing - Tried changing the tune file to another 99 Turbo ls1 that runs fine, same problem.
09-05-2008, 02:53 AM
#2
Launching!
iTrader: (27)
Join Date: Mar 2006
Location: Tucson AZ
Posts: 223
Likes: 0
Received 0 Likes
on
0 Posts
Did you disable to knock sensors with somesort of tunning software? Alot of people reduce sensitivity by %15. If you havent tunned them out and just remove them you will have constand knock retard.
09-05-2008, 06:39 PM
#5
TECH Regular
Thread Starter
iTrader: (2)
Join Date: Feb 2004
Location: 1985
Posts: 426
Likes: 0
Received 0 Likes
on
0 Posts
The knock is 100% false knock. No I havent disabled them but Im about to- Im trying to figure out why the car shows false knock. - If it wasnt a turbo car Id shut them off.
Why will a car knock with no sensor That is the question? Burst knock is disabled
The knock is false but it is reproducable. Any time the car starts seeing boost, which will raise the map - once it reaches 95+ KPA car shows max allowed knock for whatever RPM its at.
I can post the tune, but Im more interested in the theroy right. Why will a car knock with no sensor - The false knock is the same as the harness being unplugged.
PE is enabled on this car anytime MAP is over 65kpa, min RPM is 0.
Why will a car knock with no sensor That is the question? Burst knock is disabled
The knock is false but it is reproducable. Any time the car starts seeing boost, which will raise the map - once it reaches 95+ KPA car shows max allowed knock for whatever RPM its at.
I can post the tune, but Im more interested in the theroy right. Why will a car knock with no sensor - The false knock is the same as the harness being unplugged.
PE is enabled on this car anytime MAP is over 65kpa, min RPM is 0.
09-10-2008, 11:43 AM
#9
TECH Regular
Thread Starter
iTrader: (2)
Join Date: Feb 2004
Location: 1985
Posts: 426
Likes: 0
Received 0 Likes
on
0 Posts
It may only be knocking in PE, but it wasn't knocking when entering or being in PE. The knock can only be reproduced at a certain MAP KPA.
Unless someone can explain to me this failsafe and how it works- Im not convinced.
Checked the wiring, and replaced the sensors 3 times and the entire harness once. Car always knocks above 95 kpa, any RPM. Car is in PE after 65 kpa at any rpm. All sensors working properly and confirmed wiring good and confirmed- Car still knocks above 95 kpa.
Replaced PCM - uploaded tune, car sees 1º knock at 4500 rpm and 5200. Pulled 2ºs time and the car screams no knock with a rich AF on PLX wideband but safe.
Explain to me where the fail safe is and how it is no longer needed when the PCM was changed.
ps. Just wanted to state that I have a lot of respect for Frost and the other tuners that do nothing but give free help and contribute-
Unless someone can explain to me this failsafe and how it works- Im not convinced.
Checked the wiring, and replaced the sensors 3 times and the entire harness once. Car always knocks above 95 kpa, any RPM. Car is in PE after 65 kpa at any rpm. All sensors working properly and confirmed wiring good and confirmed- Car still knocks above 95 kpa.
Replaced PCM - uploaded tune, car sees 1º knock at 4500 rpm and 5200. Pulled 2ºs time and the car screams no knock with a rich AF on PLX wideband but safe.
Explain to me where the fail safe is and how it is no longer needed when the PCM was changed.
ps. Just wanted to state that I have a lot of respect for Frost and the other tuners that do nothing but give free help and contribute-
09-10-2008, 12:12 PM
#10
It may only be knocking in PE, but it wasn't knocking when entering or being in PE. The knock can only be reproduced at a certain MAP KPA.
Unless someone can explain to me this failsafe and how it works- Im not convinced.
Checked the wiring, and replaced the sensors 3 times and the entire harness once. Car always knocks above 95 kpa, any RPM. Car is in PE after 65 kpa at any rpm. All sensors working properly and confirmed wiring good and confirmed- Car still knocks above 95 kpa.
Replaced PCM - uploaded tune, car sees 1º knock at 4500 rpm and 5200. Pulled 2ºs time and the car screams no knock with a rich AF on PLX wideband but safe.
Explain to me where the fail safe is and how it is no longer needed when the PCM was changed.
ps. Just wanted to state that I have a lot of respect for Frost and the other tuners that do nothing but give free help and contribute-
Unless someone can explain to me this failsafe and how it works- Im not convinced.
Checked the wiring, and replaced the sensors 3 times and the entire harness once. Car always knocks above 95 kpa, any RPM. Car is in PE after 65 kpa at any rpm. All sensors working properly and confirmed wiring good and confirmed- Car still knocks above 95 kpa.
Replaced PCM - uploaded tune, car sees 1º knock at 4500 rpm and 5200. Pulled 2ºs time and the car screams no knock with a rich AF on PLX wideband but safe.
Explain to me where the fail safe is and how it is no longer needed when the PCM was changed.
ps. Just wanted to state that I have a lot of respect for Frost and the other tuners that do nothing but give free help and contribute-
You may be getting false knock, but per the title of this thread, if they are unplugged, your get a -4 (oem value for max KR in PE) pull in PE . I am not talking about functional sensors and harnesses here...
09-10-2008, 01:22 PM
#11
TECH Regular
Thread Starter
iTrader: (2)
Join Date: Feb 2004
Location: 1985
Posts: 426
Likes: 0
Received 0 Likes
on
0 Posts
So I am still looking for the answer on why a car will knock with the sensors unplugged.
It has been stated that there is a fail safe for bad sensor- Then what is the PCM asking for to determine bad sensor?
If I am to be ignorant and go on only what Ive read- what I am being told is that if a car is in maximum load PE state , and has no knock, then the PCM thinks the sensor is bad, and inturn will pull max KR for PE.
I was under this impression before, but was hoping someone actually knew the exact case and reasoning.
So then by that logic, a car in perfect running condition with the knock sensors plugged in will get false knock because it runs too well? ( but I think what you are saying is that the knock sensors need to report some sort of value - so unplugged wont work- since a needed value has to be checked against the sensitivity settings to see if it is high enough vaule for knock )
Edit: I should have made this post similar to the no response topic I posted on HPtuners. Car see's the exact same knock, even if the sensors are unplugged.
It has been stated that there is a fail safe for bad sensor- Then what is the PCM asking for to determine bad sensor?
If I am to be ignorant and go on only what Ive read- what I am being told is that if a car is in maximum load PE state , and has no knock, then the PCM thinks the sensor is bad, and inturn will pull max KR for PE.
I was under this impression before, but was hoping someone actually knew the exact case and reasoning.
So then by that logic, a car in perfect running condition with the knock sensors plugged in will get false knock because it runs too well? ( but I think what you are saying is that the knock sensors need to report some sort of value - so unplugged wont work- since a needed value has to be checked against the sensitivity settings to see if it is high enough vaule for knock )
Edit: I should have made this post similar to the no response topic I posted on HPtuners. Car see's the exact same knock, even if the sensors are unplugged.
Last edited by BuffJoeyD; 09-10-2008 at 01:28 PM.
