afgunn

94 Coupe

Observing and recording using DataMaster at idle and cruising, the Knock Count is constantly counting FAST - going to 65,535 and starting over. Knock sensor problem? Will a lifter tapping trigger the knock sensor(s)?

The engine is quiet and smooth at idle and cruise. To me the hydraulic roller lifters make more noise than standard hydraulic lifters at idle. I assumed the noise is the rattle from the lifter links that keep the roller lifters from rotating. Yes/NO? Would this trip the knock sensor(s)?

Jaxley

Pull the knock sensor wire and see if you still get counts. also, check the KS. ~4k ohms.

afgunn

Good call! Anyone know where the knock sensor(s, 1 or 2?) and the connector are located on my 94 Coupe?

Ozzstar

If you read the online Datamaster manual what you are seeing is normal. It states that on start up is where most counts will jump up very rapidly. The knock sensors are located on both right and left sides of the engine block below the cylinder heads about midway. They each have a small protective metal shield cover held on with two small bolts. You can view them from under the car looking up.

afgunn

I get knock counts constantly at idle or cruising. The counter is constantly counting, it never stops - 65,535 and then it starts again. The counter is counting very, very fast like every time a piston fires or faster.

Thanks for the location info. I guess they are hard to get to from the top of the engine?

WW7

I do know that knock sensors have to be torqued properly or you can get false readings from the sensor...I have a friend that tightened his knock sensor without a torque wrench and tightened it way to tight..He got excessive knock counts until he removed the sensor and torqued it to spec, then all was well.....Maybe someone replaced the knock sensor on your car before you owned it and torqued one or both to tight....WW

afgunn

Interesting... I will definitely check that. Thanks.

afgunn

I think I have found the knock sensors. I have 2 - left and right side about halfway between front and back and just above the oil pan. I will have to get the car on ramps to reach the sensors, so it may be a while. I am changing the spark plugs right now.

Thanks for all the help guys! Much appreciated!

Ozzstar

Thats how the datamaster tunercat manual describes the operation. Go to page 27....3.8.4.3 Knock Count.......http://www.tunercat.com/software/Dat...32man_v400.pdf

Jaxley

I dont have the info for that specific year, but be prepared to drain the coolant if you're taking out the KS. I know on the 90-91 you have to. Just a warning, unless someone with that year can speak differently.

afgunn

Thanks. Yes it requires a coolant drain, and while it is drained, I will be replacing both Knock Sensors and a coolant hose that I need to replace.

afgunn

Replaced the spark plugs yesterday and now there are no knocks at idle or cruise, but I have misfires at high speed - ~5000rmp. The spark plugs that I pulled out were all equally black and sooty. I am fairly sure that the engine is running too rich, but I am going to change the O2 sensors first since the car has ~76K miles and both knock sensors as well. I broke one, it stays connected but may not over time.

I pulled one of the new plugs today, and black sooty deposits are starting to build up. Again, this is further evidence that the engine is running too rich, but I do not think it is time to start tuning the engine. Need to make sure I have good knock and O2 sensors first.

Yorcci

You can change the knock sensor without draining the coolant. But you must have the car quite high to get easy access to the KS. Just a few weeks ago replaced mine, took like one minute after the covering plate was out of the way.

Just have the KS ready in the other hand while taking the old one off. It leakes just a few drops if you are quick and have the coolant system sealed. As soon as you've got the new KS on the threads, it's a child'd play.

WW7

This is the way I did my knock sensor, you only lose a small bit of coolant and it's much easier then draining the system...I didn't lose any more then an ounce of coolant doing it this way...I believe the fact that your opening up a small hole in a vacuum is what stops much coolant from leaking out, ( it's hard to drain from a vacuum) sort of like trying to pour from a gas can without opening up the vent....But , if you take off the radiator cap before pulling the knock sensor , then you'll get soaked with coolant........WW

afgunn

OK, I may try it this way. I did this with the coolant temperature sensor, but then I lost about a cup full or more. I do have to change a coolant hose up top from the throttle body, but I could do it last.

Do you know the torque value for the knock sensor on my 94 LT1?

afgunn

OK, I may try it this way. I did this with the coolant temperature sensor, but then I lost about a cup full or more. I do have to change a coolant hose up top from the throttle body, but I could do it last.

Do you know the torque value for the knock sensor on my 94 LT1?

I googled and found 14 lbft, is this correct?

Yorcci

That sounds about right.

I don't remember it anymore, it was a real pain to find in the FSM, but I'm certain that it was a relatively 'low' number, something like 20 Nm, which is very close to 14 lb-ft.