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?

------------------
90 RS
305
700r4


Moderator
www.lg4performanceteam.org

 

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

Tim

 

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

------------------
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

 

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

 

The resitor is exactyl 3900 ohms

 

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