constant knock count of 9, no matter what
Sep 18, 2014, 06:45 AM
#1
constant knock count of 9, no matter what
car is 06 RS
built a new 2.2 LR motor. installed it in the car. did some initial break in. then some light pulls on the dyno. then did first power full, saw knock count was at 9. did some change to the map. still see 9 knock count. changed everything on the map to reduce knock. didn't make any difference.
things tried so far:
changed ECU
different ROM
changed knock sensor
tested knock sensor wire
unplugged knock sensor
plug different sensor thats not on the block
new battery
the knock would show after 3 rpm, at various rpm. never below 9 or above 9, just at 9. once knock comes on, the octane level drops to zero instantly, not gradually.
what's crazy is that it does the same thing with the knock sensor unplugged completely. or even removed from the block.
built a new 2.2 LR motor. installed it in the car. did some initial break in. then some light pulls on the dyno. then did first power full, saw knock count was at 9. did some change to the map. still see 9 knock count. changed everything on the map to reduce knock. didn't make any difference.
things tried so far:
changed ECU
different ROM
changed knock sensor
tested knock sensor wire
unplugged knock sensor
plug different sensor thats not on the block
new battery
the knock would show after 3 rpm, at various rpm. never below 9 or above 9, just at 9. once knock comes on, the octane level drops to zero instantly, not gradually.
what's crazy is that it does the same thing with the knock sensor unplugged completely. or even removed from the block.
Sep 18, 2014, 07:04 AM
#4
basically comes down to not the senor at all, because they unlugged it and also test the wire from sensor the the ecu and the issues is still there.
something else is causing the ecu to default to 9 knock count. not from the sensor itself.
something else is causing the ecu to default to 9 knock count. not from the sensor itself.
Sep 18, 2014, 07:28 AM
#7
I would go along with an external source of noise if it wasn't so precise as to always cause 9 counts of knock. I don't know of many downpipes that can rattle into the frame that accurately. 
Really this is an insane issue that I've never heard or seen of before, if anyone has any ideas though please chime in. It would be great to see him racing with the NARRA Time Trial series at Lime Rock Park Friday and Saturday as we are sharing the track with the Trans Am series.
Really this is an insane issue that I've never heard or seen of before, if anyone has any ideas though please chime in. It would be great to see him racing with the NARRA Time Trial series at Lime Rock Park Friday and Saturday as we are sharing the track with the Trans Am series.
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Sep 18, 2014, 12:02 PM
#9
A constant knock count of 9 means the knock sensor is disconnected or defective.
Based on what you have said you tried I would guess there is probably a disconnect somewhere between the knock sensor plug and the ecu plug. Playing with the knock sensitivity tables won't help.
Based on what you have said you tried I would guess there is probably a disconnect somewhere between the knock sensor plug and the ecu plug. Playing with the knock sensitivity tables won't help.
Last edited by wreckleford; Sep 18, 2014 at 12:07 PM.
Sep 18, 2014, 12:11 PM
#10
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^^x2 Highly doubt the sensor is actually picking anything up, false or real.
does the knock sensor use the sensor body as a ground? If so, could be a bad ground on the block.
Op says the wiring has been tested, ecu swapped and sensor changed. Id still be suspect of the wiring. How was it tested? Was there any abnormal resistance? Maybe try messing with the wiring while testing to make sure its not just an intermittent broken signal.
does the knock sensor use the sensor body as a ground? If so, could be a bad ground on the block.
Op says the wiring has been tested, ecu swapped and sensor changed. Id still be suspect of the wiring. How was it tested? Was there any abnormal resistance? Maybe try messing with the wiring while testing to make sure its not just an intermittent broken signal.
Sep 18, 2014, 12:38 PM
#12
Interesting, I never knew the default of it not getting a signal was to trigger 9 counts of knock. Sounds like a bad ground or knock sensor circuit shorting out.
Maybe you could run separate wiring to and from the ECU with it's own power, signal and ground as needed?
Maybe you could run separate wiring to and from the ECU with it's own power, signal and ground as needed?
Sep 18, 2014, 01:01 PM
#13
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There is definitely something wrong with the signal/sensor. When I forgot to plug my sensor in I read 7 counts of knock everywhere.
Have you logged knock voltage? I'm sure it doesn't change but might be a clue.
Have you logged knock voltage? I'm sure it doesn't change but might be a clue.
Sep 18, 2014, 01:49 PM
#15
Update just in case he doesn't get back in here right away. They tried a 3rd sensor and all seems to be normal again... I guess never assume! Also if you want to bypass the factory wiring harness the Knock sensor is calibrated to work with a certain wire length and wire resistance so it's not as easy to just replace the circuit as I would have imagined.