I know the risks of unplugging the knock sensor

[strunk]

of unplugging the knock sensor. I don't exactly remember when my car started to do this, but basically lately i have been experiencing really slow acceleration. Accelerating up to sixty is OK, it is sluggish but it moves up to 60 decently quick. Once i reach sixty if i throttle up and try to go faster, the turbo spools (stock t25) but the engine rpms don't move, actually sometime is notice they actually drop 500 or so rpm's...I have tried so many things to fix this problem, my car is an auto by the way. I was thinking maybee the car was getting stuck in fourth so i took off over drive, and tried driving it that way. There was still no acceleration after 60. I have done a full tune up with ngk plugs and magnacore wires, i have no boost leaks at all, i bought a new t25 and strapped that on still not fixing it, I am currently running a 3 in cat eliminating downpipe not sure if this has anything to do with it??? However, after trying all these different things and spending all this time and money, i still have no solution to the problem. I am thinking that it is some form of phantom knock, i don't think that i could possibly be knocking due to lifter tick because i have revised lifters dropped in, it has to be coming from something else. Anyway, back to the original point of the thread. I want to disconnect the knock sensor for a short while, i know that if i am knocking an leave it unplugged the engine will destroy itself and so forth. I am only going to unplug it for testing purposes, so that i can keep on trying to narrow down the problem with the acceleration. Any help would be good, later.

 

[Joesmoke]

To confirm knock, get yourself a logger. Make sure it really is not a mechanical (go over everything one more time) or HEAT related knock problem.

Dont forget, knock could be caused by damage to a piston or cylinder head surface, so if you go to test it thinking it couldnt possibly the state of tune, you still may lose the engine due to something you could not see without going into the engine.

Also, if you decide to "test" it and unplug & ground, and it is something in the circuit, you will have a brand new car, and love driving it again. The problem then is, without the KS, you might be tempted to push your tune, (more boost, timing, less fuel etc), and that will get you into trouble fast.

Heat is another problem, and even moderate spirited driving in the summer will cause IC heatsoak, leading to knock, and you'll have no protection.

If you unplug and ground to test, make sure you go easy on it, with nothing to distract you from hearing real preignition/detonation. If encountered, back off immediatly and fix the problem. Small amounts may or may not do damage, so keep that in mind. I assume you know what sounds,symptoms you're looking for. If not, give yourself lots of study time on the web to learn more about it.

With those in mind, I also STRONGLY suggest alky injection BEFORE you unplug. While not fool proof (you can still develop knock and cause damage) it will push the threshold back somewhat. Do some research on the web, especially at the turbo buick forums.

I unplugged mine only after a LOT of research, and then deciding to go with alky injection first.

Good luck!

 

[strunk]

thanks for the reply, i know it is not a heat related knock problem, my timing belt snapped about ten thousand miles ago and the entire head was rebuilt and ported out. The cylinders were all checked and they are all fine. Yeah, i am not going to get carried away with it, all i am trying to do is regain some of my accerleration and see if knock is actually the problem here or if its something else. I dont intend to keep the ks unplugged for long, like i stated previously its only for testing purposes. Where is the plug located in the engine, i know that the actually sensor is mouned to the block a couple of inches below the intake manifold. My question is where is the grey plug located that i have to unplug. thanks

 

[Joesmoke]

Follow the wires from the back of the KS to a brace mounted on the block. The plug is there. The plug from the car is actually mounted/clipped on to that brace. BUT....

You'll have to ground the sensor so it will not default to limp home mode, which is 9 or 11 counts of knock, all the time. Remove the sensor from the block but leave it plugged in. Now run a wire to the sensor body, and ground that. Support the sensor away from the block with something, and you're done. A bad ground will throw a code and default to limp home mode.

Good luck

 

[strunk]

joesmoke, can you get more specific? Is there any guide on how to do it that i can read anywhere?? thanks

 

[Joesmoke]

**For anyone reading this, please be fully aware of what you are doing. This is generally not a recomended procedure. Do at your own risk**

Anyways...

Nope, no guide, pretty frowned upon actually (most of the time for good reason!). Just figured out how to do it through bits of info here and there.

1.Unplug KS from harness to car. Plug at bracket, follow the ks wires to it, its deep in there so feel around. I did it from the drivers side, but have fairly skinny arms.

2.Remove KS from block.

3.On the back of ks where the wires attach to it, there is some metal that flows to the body of the ks. Solder a peice of wire to that. That will be your ground. Do not attach the other end to ground yet. It will be more clear when you look at it in your hands.

4.Reinstall KS to block. Watch torque settings.

5.Plug ks wires back into car harness (plug on bracket)

6.Find ground for the wire you soldered to the back of the ks. Firmly attach to ground.

Arg, its kinda like writing a manual for how to kill a person, but worse because this your engine!

Good luck.

 

[strunk]

T hanks, that "guide" was very helpful its raining here today, but maybee tomorrow ill test it out. Thanks again, later

 

[Nicholas Gironda]

• Can you tell me what happen with all this madness?I just have to hear the end Rusult.