I built my motor about 2 years ago and have about 2500 miles on it. I have never seen any knock retard. BUT last week I was getting a code43. Some research led me to replace the knock sensor. When I went under the car and went to remove it the threaded portion snapped off the body of the knock sensor (and quite easily) leaving me with the equivalent of a snapped bolt in the block. I bolt extractor made short work of it.

I got the new knock sensor installed and cleared the code, it did not come back so It was odiously a faulty knock sensor. But the car was just not running to good so I scanned it and found LOADS "Knock Counts" and a lot of spark advance being pulled due to "knock". It was pulling between 1*-3* just off idle, and up to 9* at most rpms. It stayed fairly constant at any throttle position between 4-9*. The only time it goes away completely is on idle (sometimes) or when coasting or with cruse set on the expressway on level road (Any incline and it will show knock).

My though is I damaged the knock sensor installing it, but it still had enough continuity to have not throw a code. But it would not detect knock (dangerous situation, but I guess I put the motor threw a good test then. I have not been easy on it). Now I got the new sensor on that works and its hearing my noisy valve train and its not real knock. I have the stock LT1 Knock Module in the PCM. I have not tried any higher than normal (93) octane fuel. Do you think it would be a good test or should I just assume its false knock.



I believe there are two options when it comes to false knock. LT4 Knock Module (about $100 wherever you order it now days). Or the resistor mod.

Does the resistor mod work well on a 95?., I heard it was designed for 93's becuase they can not change out the module, but it will work just as good on my 95 right? I would prefer to spend $10 on resistors than $100 on a knock module. Would the module be safer or more efficient?


Your thought? Thanks for looking :-)


-kyle-

 

Are you sure you got the correct (93-95) knock sensor for your engine? How tight did you install it? Over-tightening will damage it and cause excessive knock signals.

The resistor works, because it reduced the sensitivity of the knock sensor circuit. But it doesn't "eliminate" false knock, just limits the sensitivity, and reduces knock retard. It would also reduce sensitivity to true knock, which isn't good.

I wouldn't assume its false knock and ignore it or cover it up.

 

Hey injuneer, thanks for popping in - your always here to help people and we really appreciate it. Thanks for your input :-)

The sensor I used was a Borg Warned (BWD Automotive) S8009. It is what Advanced sold me. After you mentioned it I decided to double check and yes it is the correct part as per BWD E-catalog:

http://www.bwdautomotive.com/Online%...g/Content.aspx



I also measured resistance between the case (ground) and the center terminal and they matched before the install.



The resistors effectually do the same as changing to a lt4 module correct?. Really no difference either way?


So I am fairly cretin I have the correct sensor. I was careful when installing because I broke the first one. This time I measured and torqued it to 14 ft/lbs(felt to loose, but that's the spec)

 

Need to make sure you reset the pcm after the knock sensor code even if the code has been cleared the pcm will 'remember' where the knock was and will tend to want to pull it from then on. This is one of the reasons people have hell getting rid of knock retard. Once the pcm 'thinks' it has detected knock, it will begin to pull timing there for a long time knock counts increasing or not.

IIRC you have stuff to flash your pcm. What I would do is just reflash it with your current tune file. I have had issues in the past where pulling the pcm fuse or the battery cable would not reset the pcm wrt knock retard.

Hope that helps.

 

ok great tip. I will go do that now and let you know how it works. (always get a little nervous when it comes to flashing, I have smoked 3 PCM's). But i know i will have to do it, just keep fingers crossed.

 

hey ws6t4. I did a re flash with the same tune I have now and get the same results. At least I know I am staring with a clean slate (blm wise)

I picked up the resistors and think I am going to give them a shot.

Anyone object to the resistor plan? Any negative feedback on it? What about on a 95?

Thanks you everyone.

-kyle-

 

The "resistors" do not do the same thing as the LT4 Knock Module. The knock module is a filter circuit that "tunes out" noise related to the Crane Gold roller rockers used in the LT4 engines. It may filter out other spurious noise. It allows the known true knock signals to get through to the PCM.

The resistors on the other hand, simply "deaden" the knock sensor's response ot ALL noise - false or true knock. In effect, you get less false knock, and less protection from true knock.

 

So the lt4 module is the way to go for sure then. I will get one ordered :-)

thank you