Rock90rs

iTrader: (3)

I busted the end of it off during my header install. Right now it is obviously not hooked up. Ive known a few TPI guys that leave theirs disconnected because of their gear drives. I know when it sences a knock it grounds to the ECM. If its not connected, then it cannot ground, right? A mechanic told me that leaving it disconnected will cause it to throw a code, retard the timing and run lean. (with possibility of burning a piston.) So far it has run no code, and the guy i know with the gear drive has left his unplugged for some time with no problems.

What should i do? go run out there now and change it? or can it wait untill I have the time to do it?

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90 RS
305
700r4


Moderator
www.lg4performanceteam.org

Tim Burgess

You should replace it, but leaving it disconnected for a while should not hurt the motor - unless you hear excessive pinging, that is.

Tim

Nitro Don

When I disconected the knock sensor on my
90 TA it threw a code and ran like crap.
So, I mounted an other knock sensor under the dash,grounded it and wired a on/off/on toggle switch spliced in between the the real knock sensor wire going to the ECM.
Now when I want to run without the sensor I hit the switch over to the dummy sensor and the ECM still thinks its reading the sensor thats in the engine.
Hope this helps,
Don

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1990 Trans Am WS6
305TPI 700R4

ENGINE:
150hp NOS kit
March underdrive pulleys
Edelbrock headers(JetHot)
Mac off-road pipe
Flowmaster exaust
Jacobs ultra coil
K&N filter
Fulley ported base,
runners,& plenum
Crane AFPR
Hypertech airfoil
Crane 1.6 rockers
210/220 .533/.544 Cam
W/P Torquer heads
Edelbrock TPI Base
Edelbrock TI Runners
Edelbrock 52mm T.B.
TRANSMISSION:
Richmond 3.73's
Auburn posi
B&M Mega shifter
B&M Transpak
Vette servo

FUTURE MODS:
210/220 .533/.544 Cam
W/P Torquer heads
Edelbrock Base
Edelbrock Runners
Edelbrock 52mm TB

BEST RUN:
12.48 @ 109.23 MPH

Tim Burgess

Another way to do the bypass is to measure the resistance of your knock sensor & use a resistor close to that value in place of the sensor. I did this for a while after installing my gear drive to verify that it was not causing the ECM to think detonation was occuring - turns out the gear drive does not cause a problem with the knock retard system. The resistor prevents the ECM from setting a code by simulating the currrent flow that would normally occur with the sensor in place.

Tim

Blade

The resitor is exactyl 3900 ohms

Tim Burgess

The resistance actually varies, depending on the year & engine VIN number, so it's best to measure the sensor in your setup, to be sure of its resistance value.

Tim