G50 Knock Sensors

[cientortas]

I searched and couldn't find anything definitive on this. My 94 Q is not throwing any codes (no KS code). However, the Knock Sensors ohm outside the range. One is 700K and the other is dead...reading 18 million ohms. The car drives great...the only issue right now is the hard 1-2 shift and slow 2-3 shift that a lot of folks experience with these trannys. Doubt that is a KS issue. Should I go ahead and do the entire under plenum job (hasn't been done ever). Or can I keep driving like this until I get the code?

Haven't had any pinging or any hesitation at all under acceleration. Thanks for the help.

[Q451990]

Bad knock sensors won't turn the check engine light on on your dash, but the code should be stored in the ECU. When you do the ECU check, do you get a code 55? Either way, properly functioning knock sensors will improve the driveability of your Q pretty substantially. Most people describe bad knock sensors as "something just doesn't feel quite right" - which is a result of the ECU putting the fuel mixture maps as rich as possible in an effort to protect the engine from knock. Essentially the ECU behaves like it's hearing knock all of the time if it knows the sensors are bad.

Heath

[cientortas]

Thank Heath. Yes, code 55 comes back when I do the ECU check. If the ECU makes the fuel maps as rich as possible, should I be noticing a fuel mileage decrease? The car runs well, but mileage isn't great. 13 city and 17-18 hwy.

[Q451990]

Very odd to get a code 55 with the ECU check. I would recheck your measurements... I've never heard of the two not agreeing.

Heath

[kevindanielk]

Does your Q spin the tires, from a standstill, if you stomp the gas pedal all the way down? That's what the right feeling is........I drove my Q for years, with bad knock sensors, not knowing that "right feeling." First test drive after changing my bad KS, I was like, wow, THIS is what a 300hp V8 should feel like )
Big, big difference in takeoff. Make sure you use oem Nissan sensors.