Marc8090

I did a search and looked through older posts. You mention a couple ways to desensitize or bypass the knock sensor. For a '90 SD car, you said a 3.9 resistor. Is this 3.9 thousand ohms? Would I simply splice it into the wire near the sensor in series? I guess the sensor works on changing resistance and this much resistance is equivalent to no knock, correct? Will this set a code? Also, I bought some pipe fittings the correct size to either move the sensor out of the block an inch or two, and barbed fittings to connect it with a short piece of rubber hose(obviously has to be grounded to work). What of the three do you recommend I try first, moving it out of the block, rubber hose, or the resistor. Your opinion is greatly appreciated. Thanks, and anybody else with an opinion or suggestion please respond.

MikeS

Sorry I'm not Ed with your answer, but I had to ask...

What is it you are doing this for? I don't understand the point.

Marc8090

I'm having a problem with the knock sensor pulling out timing and I don't think it's detonation. On the dyno, at WOT it pulls out 7-8*. This is with base timing of 6* and 30-31* advance which should be fine for a small block chevy. The bottom end doesn't know it's fuel injected. This was at an A/F ratio of high 11's to 1, WAY to rich. Everyone I've spoken to says that running that rich there is no way it's detonation. Also, under light acceleration, remaining in closed loop, it pulls out 10-11*. I know this is hurting my hp. The car made decent hp, but it should make more. I had the chip leaned out, but want to get the timing straightened out before I go back to the dyno to recheck the A/F ratio. Dyno time ain't cheap!

Ed Maher

I'd just use a 3.9k ohm resistor. Mechanically desensitizing it may or may not accomplish what you want.

Marc8090

Would I simply cut the one wire going to the sensor and splice the resistor in? Is there any polarity on a resistor like on a diode? Will the resistor get hot or can I cover the connections and resistor itself in shrinkwrap or something similar? Thanks Ed.

MikeS

Resistors do not have any polarity. You can use them either way. They can get quite hot though. Since Ed has apparently done this before, he can say just how hot and how exactly to hook it up. Just thought I'd throw in the polarity answer as quick as i could for you.

Marc8090

Thanks guys. I put the resitor in tonight and will see how the car drives tomorrow. I'll let you know what happens.

Ed Maher

No, the resistor won't get hot.

MikeS

Ok, I won't argue that. Guess it doesn't get hot in this application. Put it too close to the headers and it will