pomanferrari

iTrader: (1)

My knock sensor was reporting 100+ for knock value on the datalogit.

I checked it and it was loose plus the plastic overmold was cracking. I filled over this overmold with plastic dip and tightened the knock sensor.

Now, nothing higher than 20 for knock even at 13 psi in fourth gear at 4000 rpm.

Oh, the map was dyno tuned for an almost exact set up as mine. Reportedly 300 hp at the wheel at 13 psi.

I'm going to get mine dyno tuned once I find a free day to do so.

Zyon13B

Cool, I might try that also.

SWAT81

iTrader: (14)

I did the paper clip trick to see why my engine check light is coming on and it gave me 5 blinks which means knock sensor. Should I replace the whole sensor ot try doing what u did pomanferrari?

reza

ahh...you are making the knock sensor deaf? no?
It probably could not hear all the knocking now..

Reza

pomanferrari

iTrader: (1)

The portion that I put the plasti-kote over is the portion where you see a wire poking out of. That portion houses the electronics (at least I saw a resistor in there) for the microphone at the other end of the knock sensor.

I don't think the plasti-kote does anything except to protect the electronics. I think it's the tightening of the sensor that did the trick.

clayne

I've never seen a high knock on heavy load - always off load. Consistently day to day of around 100-110. Highest I've ever seen was 160. I never really put too much stock into the FD sensor seeing as how it is so inconsistent, but I'll check mine out like you did yours.

BTW: My PFC never throws an engine check light on high knock values.. Anyone else?

93 R1

160...damn.

I never see above 65-70 even while cruising off-load.

donny

The PFC does nothing with the knock sensor readings. It will read it but makes no adjustments if the knock level gets too high. Thats why a J&S Knock sensor is helpful.
I just learned this info today..

I can see the internals of my knock sensor as well. What happens is the heat over time melts the original filling away. I filled mine with liquid electrical tape.

ZeroBanger

Mine read upto 192 after a 1/4 mile run at the track on my old engine. Turns out I had a broken motor mount. After my new engine was put in with the new motor mount my Knock is from 5-35.

Just Bring It

where is our knock sensor located? Anybody have a picture ?

Thanks

Herblenny

iTrader: (13)

Highest I seen so far is 74..

Hope thats o.k..

What is bad knock number??

user 9348703

This is an ongoing problem:

Retorque it anytime your engine is out. A little sealant, glue or epoxy (not too much) will prevent it from loosing.

They seem to loosen after quite a bit of driving and give BIG knock readings since the sensor jumps around.

ZeroBanger

one that causes detonation.

user 9348703

Usually 74 on a daily basis isnt terrible, but not great either.

I havent passed 20 even if I go nuts in my FD. I use to be in the 100s sometimes, until I learned a little more hehe

74 isnt bad though if you didnt drive it for a few days and such.

Clean plugs, change oil, blah blah if you havent lately and re-check again. Most likely if you havent done these for a while it will increase your knock a few points.

user 9348703

Kind of depends though. As in the plugs and ***** I mentioned. 74 isnt that much and it depends where he got it, start-ups can go high, 9000rpms tends to make a higher knock hehe, and so on......

In general if I saw 74 during one of those above mentioned times I would diregard it.

Plus its getting cold out, or hot depending on where you are, so knock readings will change a little depending on mods and when the last time you did you tunning.

pomanferrari

iTrader: (1)

I saw a post from the datalogit maker that he was told by an Apexi engineer that, assuming knock sensor is fine etc., anything over 69 is bad, real bad.

Mine never show more than 20 off load or whatever now.

user 9348703

pomanferrari---You have been lied to. APEXi says in a pretty much quote "the PFC and the stock knock sensor do not understand each other 100% so the knock isnt so accurate"

ZeroBanger

Jason,

I wasn't saying 74 is a bad knock number, Im simply answering his question. He asked what a bad knock number is, the answer is simpley one that causes detonation.

I always had close to 200 on my old engine, no big deal.

Herblenny

iTrader: (13)

I didn't mean to cause any arguements..

I'm not sure when I hit 74 knock reading.. but I notice my peak was 74...
I'm starting to watch it because friend of mine blew his engine recently.. and I believe it was due to bad plugs.. before that, I never even thought about watching knock reading..

I'll change out my plugs and see if it lowers the knock.. maybe I also need to do some torquing.

ZeroBanger

Hey, jason and I were not arguing. I just made a smart *** comment ....just being me.

anyway, every car is different. If a knock of 74 is NORMAL for your car, then dont worry. For example after you check your knock after WOT, lets say its 74. You do this day after day and its 65-80 consistenly...in that case dont worry about it.

lets say its always 65-80 and all of a sudden you hit 100, I would begin to worry.

In otherwords, the number by itself means nothing, but whats normal for your car is the key.

Herblenny

iTrader: (13)

Thats a great advice.. thanks.. I will test it out.. I'll drive around this weekend and see when I hit my max knock.. change my plugs (its only 2K miles old) and see if it makes any difference..

J.S.J

I believe the knock sensor is a Paleozoic Crystal which reacts to vibration/sounds which in turn is seen by the engine computer. The exact way an FD/Mazda system reacts is not know by me but most systems will look on the line and if it sees knock it will retard the ignition timing until it stops. Knock is normally generated by a combination of high combustion temps, lean mixture and advanced ignition timing.

user 9348703

Im not argueing at all.

I was just throwing out that info.

Yeah Im sure some cars last a long time with high knocks and others blow engines with 3 knock hehe

In general I dont think 74 is that bad. I mean it all depends, I have the tadletail on my PFC on, so I can read where I went when I cant always look at my gauges to worry.

I mean I reset the tadletail too, after the car is warmed up, and anytime I hit a high knock, then see if its a repeat or just a bump or air, dirt (no air filter) or what to see if anything is a problem or might be in the future.

Actually I think this is a great discusion. I know it has been brought up quite a few times in the past, but its something ongoing and its worry some, especially if you have your warning lights on and your engine light flickers at you anything above 80 knock was it? Correct me if im wrong since I cant remember.

Bad knock is repeatative, not a one time thing. If you rev and you always get a knock a 3000rpm or 6000rpm or whenever, THESE ARE VERY BAD if high. Check knock sensor,�@torque sensor, tune as needed.

If your running lets say everyday at like 50-60 I wouldnt worry a bit. Engine produces a small amount of knock with age (if this is your case). One day you start running at 70-80 knock. Time to start troubleshooting, not screwed by all means, but I would start to look. 80-90, better check the sensor or change it and tune as needed. Anything at 100 or close to it or hitting it several times is BAD, IF, I stress "IF" you have done the above first. At 100 you will be in deep poop soon, or your PFC doesnt like you or your knock sensor, one or the other, so take it to a pro, preferably APEXi and say WTF with your PFC! hehe I did.......

herblenny---Good luck man, let us know..

ZeroBanger--No harm intended, I thought it was all good. Dont mind my english is terrible since I dont get to write it much except for the internet now days LOL!

Herblenny

iTrader: (13)

JT-.

Your english is better than mine!!
I went to top 25 University, got B on my English 101..

Anyhow, Thanks for that info.. I really never thought about the knock.. I'm very tempted to just go out for some run.. Make sure when I hit that 74.. I'll definitely post my results..

user 9348703

haha

I would have failed LOL

Sure let us know how it goes of course..