hi guys, i need some brain here, mine got fried today. after i relocated and installed a new knock sensor, i turned on the car, factory boost gauge was dead all of a sudden and the HICAS light is on., i drove it, it drove normal, but boost is still low.
here is what i did :
i have a knock sensor plug ( the end plug to the sensor itslef) which has 2 wires coming out.
I located the old harness , gray oval shaped with gray tape over it, i cut that wire, stripped the old insulation, i soldered the white to one of the wires of the plug and the black to the other, covered it with electrical tape and i already had shrink tube on it.
plugged it to the OEM female harness and bolted the knock sensor to the new location.
The results were what i wrote above.
if i soldered the wrong wires, does the knock sensor itself have +/- polarity? could i have reversed it?
has anyone experienced this?
why the dead boost gauge? and HICAS light?
right now my cars battery is unplugged/dead , maybe this will reset it all.
ill check the fuses but i didn't hear any pops at all.
KNOCK SENSOR HELP-z32
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ACK
- Posts: 57
- Joined: Mon Nov 05, 2012 2:09 pm
- Car: 1994 300ZX TT, AT jspec front bumper,tail lit. Side marker
19'' XXR
79 280zx
85 Z31 Turbo 608 HP ,9.7 1/4 mi sold - Location: Los Angeles
Re: KNOCK SENSOR HELP-z32
no one?
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Shoey2
- Posts: 110
- Joined: Mon Aug 20, 2012 9:03 am
- Car: 1990 300ZX Fairlady Z Twin Turbo
- Location: Vancouver Island
Re: KNOCK SENSOR HELP-z32
sounds like you wired it backwards to me. knock sensors are one of those things that you need to torque to spec or the reading will be off if you crank it down too tight. or vice versa. that would explain the low boost if the computer thinks its knocking cause its wired back wards it will pull back power and timing and all kinds of crazy stuff to try and save the engine.
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ACK
- Posts: 57
- Joined: Mon Nov 05, 2012 2:09 pm
- Car: 1994 300ZX TT, AT jspec front bumper,tail lit. Side marker
19'' XXR
79 280zx
85 Z31 Turbo 608 HP ,9.7 1/4 mi sold - Location: Los Angeles
Re: KNOCK SENSOR HELP-z32
i torqued it down at around 15-20 lbs, normal. as far as the wiring , im guessing i may have reversed the wires. i will try to reverse it again. Its strange. Thanks for your input. however why the HICAS light and brake light? and no boost gauge? everything was fine, before this procedure..
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ACK
- Posts: 57
- Joined: Mon Nov 05, 2012 2:09 pm
- Car: 1994 300ZX TT, AT jspec front bumper,tail lit. Side marker
19'' XXR
79 280zx
85 Z31 Turbo 608 HP ,9.7 1/4 mi sold - Location: Los Angeles
Re: KNOCK SENSOR HELP-z32
so i reversed the knock sensor harness, i did this by unhooking/un-clipping the metal prongs from the gray harness and clipped them back. i basically reversed it. Im still getting the brake light , hicas light and no boost gauge.
i removed the boost gauge sensor, cleaned it and replaced it with new vacuum line. When i turn the car on it sweeps a little to the -14 side. I may have a bad sensor? I don't understand why all this happened since the new knock sensor install.
i removed the boost gauge sensor, cleaned it and replaced it with new vacuum line. When i turn the car on it sweeps a little to the -14 side. I may have a bad sensor? I don't understand why all this happened since the new knock sensor install.
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ACK
- Posts: 57
- Joined: Mon Nov 05, 2012 2:09 pm
- Car: 1994 300ZX TT, AT jspec front bumper,tail lit. Side marker
19'' XXR
79 280zx
85 Z31 Turbo 608 HP ,9.7 1/4 mi sold - Location: Los Angeles
Re: KNOCK SENSOR HELP-z32-UPDATE
k so, today i filed around with the knock sensor an its harness. I found out that the knock sensor has a positive an a ground, i was aware however i didn't know which one was which:
Looking at the connector plug, large base faced down, the left pin is signal, and right is ground, and also the center bolt hole is ground as well. So i removed the KS, an sanded the seat where the KS sits an i also sanded the bottom an inside of the bolt hole as well, with 800 grade paper. I originally had a copper washer underneath, i removed it. i torqued it down and ran the diagnosis once more, CODE 55- the car revs higher and i feel more boost. I have a feeling one of the turbo's may be going soon.
My boost gauge (factory) is still not working , i have a brake light warning light and the HICAS warning light.
Not sure why these are on. All bulbs are good, and i doubt if the electronically controlled HICAS depends on oil pressure or fluid level. but i did however add some ATF to the PS reservoir.
Looking at the connector plug, large base faced down, the left pin is signal, and right is ground, and also the center bolt hole is ground as well. So i removed the KS, an sanded the seat where the KS sits an i also sanded the bottom an inside of the bolt hole as well, with 800 grade paper. I originally had a copper washer underneath, i removed it. i torqued it down and ran the diagnosis once more, CODE 55- the car revs higher and i feel more boost. I have a feeling one of the turbo's may be going soon.
My boost gauge (factory) is still not working , i have a brake light warning light and the HICAS warning light.
Not sure why these are on. All bulbs are good, and i doubt if the electronically controlled HICAS depends on oil pressure or fluid level. but i did however add some ATF to the PS reservoir.