My longtube headers are pretty close to the frame and I sometimes get header knock. I also have crane gold roller rockers, and decent cam that all probably make a little noise. Everytime I smack 2nd and 3rd, the ECM pulls timing (knock retard) I guess and I even teflon taped the crap out of the sensor! So my question is why not just disable the knock sensor stuff in the PROM? Carbed motors dont use them so what diff would it make if I just disabled it? A TPI motor can blow-up or last just as long as a carbed motor can.

Help please, me very frustrated!
THanks,
Mike

 

I disabled the one in my father's 77 C3 vette. I retro fit TPI on his solid roller 383. It is not just a matter of turning off a setting though. There are a couple of tables that have to be adjust along with some values. It took me several attemps, but I finallly got it to work. I actually set it up so it works in extreme cases. I personally see no problem with disabling the knock sensor. Most cars I retrofit, I do not even use a knock sensor.

 

Not having tried this I would have to think that zero'ing out the max knock retard and knock attack rate tables would be a good start.

RBob.

 

Why zero them COMPLETELY out?


Wouldn't it be a good start to just take alter the tables that take out the timing for KR?

 

Sure Bob

Rather than outright disable, why not just limit the maximum amount of retarded permitted in certain circumstances. I strongly advocate controlling the Knock Retard by experimentation of all possible means: limiting the maximum amount of retard, slowing the rate of retard when knock occurs and accelerating the rate of recovery. This way, you retain the knock sensor as a "engine safety" should that bad tank of gas occur so you can at least get it home (by driving slowly) and drain the tank.

Controlling your Knock Sensor via the eprom is far better than outright disabling. Just be careful when doing it, you are risking your motor. This is one of those "changes" I would say you should get a few eproms under your belt first.

 

As another issue, I think RBob is also implying that people are sometimes too quickly to just disable the KS and not trying to determine the real source of the knock in the first place.

When I had "iron heads", I coudl not run any more spark advance than 27* in WOT. (I limited the maximum Knock Retard when in WOT to 1*...and trying to go beyond 27* just resulted in audible knock on 94 Octane).

When I swapped the "iron heads" for ported Aluminum ZZ3 heads, I scoped out the combustion chamber of the iron heads. Sharp edges all over the place (easily cut your finger), rough combustion chamber...basically a breeding ground for hot spots. No wonder I couldn't run anymore than 27*.

Before I installed the Al ZZ3 heads, I smoothened the combusition and removed all sharp edges. I never had too much to optimize the spark tables for max power before I fell ill and had to put the car in storage last year. But I was running 32* and I had absolutely no knock. Yes, these are aluminum, but I also went from a 64cc head to a 58cc head.

In closing, I am just saying that you should look at other possible reasons for knock occurring rather than just "limiting" the Knock Sensor.

 

After we started burning chips for my car it unexplainably started picking up false knock. I got tired of it so I just disconnected teh sensor and turned off the ECM code for the knock sensor. I haven't had any trouble since then. This might not have been the "best" way to do it but if you keep a close eye on your car and your a mechanic I wouldn't worry about it

 

Why change anything in the chip if you're just out to disable it? A cheap resistor will ensure you get 0 knock counts and missing a hidden table won't come back to bite you unexpectedly.

As for blowing your car up without it, look at it this way. A century or so of IC engines went by without knock sensors as a crutch. You do have ears right?

 

I guess I consider "mechanical disabling" like saturation bombing with dumb bombs while controlling the KS in the eprom burning is like using just one smart bomb.

 

Yes, I would consider myself to be mechanically inclined beings I did everything on my car myself including building the motor (with the exception of the block/crank machine work). I'm just getting frustrated with the darn KS pulling timing. I've burned 20 or so chips and the car is running REALLY decent at times (BLM's 122-130). I was worried about disabling the Knock Sensor diagnostics stuff in my .bin using Tunercat for the obvious reasons (dont want to blow her up!). But, if it was carbed I wouldn't be using a KS anyway. So........

I do like the idea of keeping KS functionality but limiting the amount of timing the KS can retard and speeding up the recovery rate. What ALL tables in tunercat will I have to modify? Will I have to change anything else after adjusting these KS tables (not KS related maybe)??

Please let me know and thanks for the continued help!

Mike (1bad91Z)

 

Make sure the wire for the KS isn't running near or around any plug wires.

I once had the KS wire wrapped around the dipstick tube. The plug wires also were touching the tube. Turns out the KS wire was picking up some kinda interferance from conducted thru the tube. The knock counter would just tick away like a clock because of that. So the timing was retarded 10° all the time.

I moved the KS wire and didn't have any trouble since.

 

1Bad91 If you want to, PM me with your e-mail address and I can mail you my father's latest *.bin file. I would by no means try using this .bin as it is set up for a very radical engine and there are some serious comprimises made to make this thing streetable, but it will give you a good idea of what I have done to tone down the knock. You do not even see any knock counts until the engine crests 4000 rpm. If you need specifics I will have to go back and look at my notes to see what I did.

 

Look at the "Maximum Knock Retard vs. RPM (In PE)" Table. This (surprisingly enough) limits the maximum amount of knock retard vs. the rpm while your in PE. It will allow the KS to work in all other situations (like you are driving up a hill, heavy load, but not in PE).

 

Glen - is this a "Stock" or modified value for this table? Also, what other table's other than Power Enrichment should I look for that is KS related?