Knock sensor - cause high idle? And torque specs??

[90de4u]

Pulled the codes from my ECU...threw a code 34 for knock sensor. Would a bad knock sensor cause the car to idle high? This is a KA24DE in a 1990 240SX...not sure what year the motor is from. I have been told 95, but could be from an S13. I have been having this high idle issue for a while now. I plugged every vacuum line except to the FPR and brake booster. Cleaned out the IACV. Tested the air regulator and IACV and both are OK. Removed the EGR, placed a block off plate with gasket to cover it, plugged the hole in the exhaust manifold. TT 300ZX fuel filter.

So my question is, would the knock sensor cause the idle to be high? ALSO, what are the torque specs for the knock sensor bolt?

[White Comet]

take a small hammer and tap near the knock sensor and listen for a change in idle, that'll let u know if its bad

[90de4u]

I took a wrench and hit the bolt and knock sensor and nothing changed. Still idles high....don't know what's up with this damn car.

[n0odle]

Can this also cause low idle? My car idles at 900 atm =/

[Dattebayo]

I took a wrench and hit the bolt and knock sensor and nothing changed.

LOL he said hit the block near the sensor, not hit the sensor its self! haha

Just go and replace it, its cheap and they can melt alot.

[90de4u]

Actually, if I hit the bolt that goes through the middle of the sensor, it would have the same effect as if I hit near the sensor. It is still sending a vibration other than the norm. Sensor is like $60, not that expensive but it really isn't a problem that I am worrying about too much if it isn't causing my high idle. Because all I really wanted to do was get rid of the high idle.

[TheOne]

bad knock sensor wont cause high idle, it might however cause the car to feel sluggish off the line(till about ~3000 or so rpm)

[White Comet]

yeah, the knock sensor might not be the source of the issue ur having trouble w/ but it wont hurt to replace

[Dattebayo]

OK, well just ignore your diagnostic computer then. I'm sure it has no real world bearing anyway

[White Comet]

i agree, if ur cars telling you something you should listen

[maxvel]

Hammer technique doesn't always work. Knock sensors are tuned at 7KHz freq range to ignore all common vibrations including your hammer

[White Comet]

^ true but many times i have seen it work, its a cheap easy way to check and then go from there

[90de4u]

I'll try again and hit near the sensor and see what happens.

Also, I checked the voltage and ohm resistance on the TPS and everything was fine. I tried to adjust the TPS anyways, and even set it as low as .32 and it still idles high. Would the TPS cause a high idle like this even though everything is checking out OK? Car is idling at 1,500rpm when fully warmed up...when driven, stopped at a light, etc. Never any lower.

[White Comet]

sometimes odd idle can be iacv but that isnt so much idle idle as crappy idle, check it anyways

[90de4u]

IACV is fine. I was wondering something. My motor is a plain federal emissions standard motor, but my ECU throws a code 35, which is for Exhaust Gas Temperature sensor. But the California emissions motor is the only one that has that sensor. Would that cause the car to idle high? Maybe the ECU is thinking the car isn't warmed up?