Knock system

Nigel

Well-Known Member
I have noticed that I seem to tickle the knock retard a little bit with no discernible pattern, and maybe more so than others with what I would think are similar conditions. I have noticed that it seems intermittent and does not seem to be affected by timing or boost changes. In the past I have looked at plugs and saw no signs on the plugs. Also, even after I broke my stock crank (which detonation would definitely help do), I saw zero signs of fretting between the cap and the block. Maybe I am fuking up, but on the other hand I run conservative timing 17 WOT and what I think is conservative AFR heavy on the alky. Anyway, in the future I decided I wanted to log the signal going to the ECM from the ESC. The powerlogger seams to only log 0-5v, but that will be OK as the signal drops from a normal of about 9V to possibly 0V. I tapped the signal from the ESC to the ECM and tapped a socket extension near the sensor for a test. Attached are the screen shots. You can see where a signal was being passed and where the ECM pulled some timing. Knock counts are picking up most of the spikes even though no timing is being pulled. Going forward when the weather is nice I plan to log this. If anybody has any good knowledge to add to this experiment please do so. My goal is to make sure that - A) I am not damaging my engine - B) that I am not picking up false knock or have a something out of spec picking up noise instead of knock.

knock test 1.jpg
knock test 2.jpg
 

Mr.Spool

Well-Known Member
what is the afr when you see knock? and have you tried taking out some advance in the areas you see knock?the knock counts in your screen shot i see are very low in the rpm range maybe pre boost,maybe pull advance there or add fuel and look for the ghost knock that way sometimes 93 really isnt 93
 

TurboTGuy

Gray Beard Member
What mods do you have? A bunch, a few? What are they?

My car is extensively modified and I have figured out over time that the stock knock sensor isn't much good on stroker/roller set-ups, bigger cams, etc. Those set-ups make a lot of noise and fool the stock sensor. I had 15 plus degree's of false knock with this new engine.

The bad part is I haven't discovered a replacement KS that works with a modified, noisy engine........I have something rattlin', against something else... I'll figure it out one day, until then, knock sensor is disconnected.

Famous carnival barker saying............"Ya' pays yer money and ya' takes yer chances....."
 

Mr.Spool

Well-Known Member
My car is extensively modified and I have figured out over time that the stock knock sensor isn't much good on stroker/roller set-ups, bigger cams, etc. Those set-ups make a lot of noise and fool the stock sensor. I had 15 plus degree's of false knock with this new engine.
i run the stock knock sensor on my nt car 0 knock at all times.
 

Nigel

Well-Known Member
what is the afr when you see knock? and have you tried taking out some advance in the areas you see knock?the knock counts in your screen shot i see are very low in the rpm range maybe pre boost,maybe pull advance there or add fuel and look for the ghost knock that way sometimes 93 really isnt 93
The screen shot is a test just to log the signal coming off the EST. Car is stationary holding 1700rpm so the ECM will react, banging the block with a socket extension. The test was successful, next step is to test under WOT.
I have seen 0.5 ish at WOT. 10.5afr. I have pulled timing at the point in the past.
My goal is to log the signal when the weather gets better. I want to see what the ESC looks like compared to the ECM reaction, maybe able to discern if it is noise or detonation, won't know till I try.
 

Nigel

Well-Known Member
What mods do you have? A bunch, a few? What are they?

My car is extensively modified and I have figured out over time that the stock knock sensor isn't much good on stroker/roller set-ups, bigger cams, etc. Those set-ups make a lot of noise and fool the stock sensor. I had 15 plus degree's of false knock with this new engine.

The bad part is I haven't discovered a replacement KS that works with a modified, noisy engine........I have something rattlin', against something else... I'll figure it out one day, until then, knock sensor is disconnected.

Famous carnival barker saying............"Ya' pays yer money and ya' takes yer chances....."
206 roller with TA stock style rockers. Nothing else note worthy that I can think of.
 

grass doctor

Dream Catcher
im sure you know this but worn out motor mounts can give false knock erracticly.. as well as crossover / downpipe hitting.. and double roller timing timing chain and gear can piss off the knock sensor too vs the OEM one... im really just following this to learn though
 

Nigel

Well-Known Member
when you pulled timing did the kr stop?have you tried taking it to 10.3/10.2?
I've pulled timing and added fuel. Sometimes the run would clean, and others I would get just a touch. I have have to go back and look, but it was usually in the same rpm range and just around 0.5 retard . Everything is fairly tight, good mounts, exhaust ...
 

Mr.Spool

Well-Known Member
but it was usually in the same rpm range and just around 0.5 retard .
ok there is something.what rpm is the kr? is it rpm related in each gear?i would look at pump pressure, fuel pressure,try to richen it up in that area.
 

Nigel

Well-Known Member
ok if nothing is hitting and your sure.also wheeelspin will cause the knock sensor to go off
I plan to do work on this when the car comes back out. That is the reason for watching the signal from the ESC to the ECM. I have checked over the car pretty well, not to say I did not overlook something. My curiosity is what kind of noise level is being picked up vs what is the ECM recognizing as knock.
 
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