LT4 knock sensor
 

what is the diff. between the LT1 & the LT4 knock sensor and is it worth it to swap ?

There is no difference in the knock sensor. There is a difference in the knock module, though.

I've herd that a loud exhaust can vibrate and make the knock sensor send a code. Is this true ?. If so, when I put a cam in and there is alot more vibration, will I need to get a LT4 sensor or module or will everything be fine (just dont want to loss any hp because of it)

No codes, it will just yank timing (and HP.) The module is a $20 piece, might as well get it.

Redhott, you have to understand however that like shoebox said, you would want to purchase the LT4 Knock Module , not the sensor. There is a knock sensor in the block, which sends a signal to the PCM. Inside the PCM, there is a module that interprets that signal to determine whether it's knock or just valvetrain noise/loud exhaust/etc. The LT4 module was designed much better at detecting actual knock and ignoring increased engine noise from roller rocker arms.

You will most likely benefit from having it, it's like 20 something bucks at GMPartsDirect.

Doesn't the knock sensor used in the LT4, being OBD2, use a different impedance than the one used in OBD1?

Yes, but that was not the specific question. :) All OBD-I vs. OBD-II knock sensors are different, but an LT4 sensor is the same as an LT1 sensor for the same year.

I'm confused, if the LT4 didn't come out till '96, how can there be an OBD1 LT4 knock sensor?

:confused: Now I am confused. :D Who said there was an OBD-I LT4 knock sensor? As you said, LT4's were OBD-II, so comparing that to the same year LT1 (also OBD-II) the sensors are the same.

I was thinking, since the author of the post had a '95 there would be a difference for him.

The knock sensers are different in obd1 and obdII cars but both are compatible with the lt4km

The LT4 knock module was used to compensate for valve train noise in the LT4 engine. Maybe an off road pipe, cut out or open headers would cause something for the sensor to detect, but I think that is even a stretch.

As ba96ta said, the knock module is compatible with all knock sensors, so you can use it if needed. You don't need to change the sensor. If you are not getting any knock detection from your valve train, it won't make a difference.

Rob you dont think that even a loud exhaust woudl cause any false knock? J/W

It's my opinion that exhaust noise alone is not going to cause knock counts. I don't think the frequency of the noise will be picked up by the sensor. Now if the exhaust causes something to rattle and the sensor picks up the rattle, that's another story.

If you are monitoring knock counts with a scanner, a common functionality test is to take a metal tool and tap on the block (or a solid bracket attached to the engine) to see if the sensor picks it up. If you have ever done this, you know that it takes a decent smack for it to register.

Of course I could be wrong, but until someone shows me different, that is where I stand. :)

ive been told i cant use a LT4 KM because i spray is this true??