IMHO it's a REAL bad idea to bypass the ks.

 

yeah suzy soccermom needs a knock sensor no doubt haha

http://maxima.gregg-henry.com/grace_imports/

here are all the pics youve sent me.

 

I've had my ks bypassed (with advanced timing) for a while and I haven't had any problems (just have to use premium fuel and listen for pinging)

 

You might be able to just relocated the KS to somewhere easier to access. I don't think I would delete it. You can gain hp with timing advanced, but I wouldn't do it without a KS. It's not that big of an expense for a little piece of mind.

The build looks delicious, BTW. I wish I could put that in my car.

 

after having a SAFC-II hooked up I would not bypass the KS

especially with an increased CR, but thats just me

 

......

 

if your ks is bypassed then what do you do if you hear pinging......

 

If you have it bypassed and are useing premium fuel[you must use premium if you bypass!] then you need to replace the k/s...

 

With the SAFC-II though, can't you monitor the engine knock? Or does it need to connect to the knock sensor to do that?

 

Why not, all with JWT ecus are running without any timing or fuel knock maps anyways..

 

Can you expand on that? I don't believe JWT would program the ecu to ignore the ks and fuel maps. How can the engine run w/o a fuel maps? You mean ignore the 02 sensor? I get great mileage with my jwt ecu. I have to think it's still using the 02 sensor.

 

Actually I meant that the stock nissan programs have 2+ different timing and fuel maps for knock or high load (4th or 5th gear) where as JWT sets all the maps the same..= no retarded timing or richened fuel for knock conditions. Ive looked at both a stock ve 5spd bin and A JWT ve 5spd bin.

 

Odd as alot of my gains I feel from the JWT is the low end/low rpm. Great response. And of course the higher rev limiter.

But what you say makes some sense as they tell you premium fuel only.

I ran the ks bypass on my JWT ecu VE. Let's just say during the summer on 91 octane, that was no-no.

 

The JWT timing maps are set +2 degrees across the map vs. a stock no knock timing map. The stock ecu only looks for knock up to about 3500 rpm anyways. The JWT ecu also has the fuel map richened up alot at high load /rpms. When I first dynoed my max with the stock ecu the afr's were pretty good but could have been richened up a bit. I have dynoed with a JWT yet but ive heard they run way rich.

 

apperently ford didnt start using knock sensors on the mustang untill the 99 cobra and look at all the guys runing all kinds of crazy high conpression and FI motors in all those old stangs with no complaints. and appearentlly disabling them isnt uncommon for newert cobras either somthing about false triggers during launch which pulls timing and scews up the run?

i moved mine to where the air box used to sit because for some reason when id bypass it it would throw a code but ive run it like that for almost 2 years with lots of spray and the last time i check my compression "before the motor died (bearings again)" it was all around 150-155

anyway really who cares what this does it sounds like hes got his **** together and if he wants to do it like that dont bother him

 

This is OT but ive always wondered how a resistor (bypass method) works when the ecu is looking for an ac voltage response from the knock sensor not a resistance?

 

Most sensors give a reading back to an ECU by varying amounts of resistance whether they take temp readings (thermistor) or position readings (potentiometer). In regards to a KS...The KS will recieve a certain amount of voltage. If things are running fine and normal then the ECU will recive a certain voltage. If a knock is detected then the sensor will give a different voltage reading back to the ECU so it can back off the timing. By using a resistor, you will give the ECU a constant reading that everything is ok. The catch is that the driver/mechanic/tuner has to be on top of their game and become the KS themselves.

 

then the JWT ECU has just become the sh1ttiest product I've ever heard of, and is far more harmful than a ebay resistor or soda pop can in the intake.

Also seeing as JWT has not released their bin files, you can forgive me for being skeptical.

 

if JWT does infact set the KS maps to match the regular maps, the resistor on a JWT equipped car wouldn't make a difference at all.

 

Hot day, loading it at low rpm, no ks protection, crap 91 octane, going up steep hill, jwt ecu = ouch

 

They dont have to release anything, I own one (its for sale btw) and have pulled the bin from it using calumsult. And like I said before A resistor to ground cannot replicate an ac voltage which is what the knock sensor puts out to the ecu. So I dont think the resistors are really doing much?? Maybe allowing some transient voltage to go to ecu? I dont know, Im just a newb

 

There may be and extreme knock safety retard built in kind of like the limp home mode but I am not sure about that either.

BTW if you havent seen these site yet:
ZTECHZ
ECCS Tuning

Youll also find links to other nissan ecu sites as well from these

 

i like how my post looks completely out of place, lol

 

Well I know of 2 members with JWT Equipped cars have blown stock engines. Regardless it makes me happy I went with an SAFC-II over a JWT

 

You're correct that an ECU is looking for voltage from a sensor. That sensor will use resistance to change the voltage signal that it is sending back to the ECU. Resistance causes a voltage drop. If you put a resistor with a given value (of resistance) in place of a KS then it is dropping the voltage going through that sensor to a given amount. In the case of the KS, you would use a resistor that gives a value back to the ECU that is the same that the ECU gets when things are normal for the KS. The bottom line is that resistance changes voltage value. I can explain further but, maybe that makes sense.

 

I understand what you are saying but the ks is a single wire unit. the ks ..itself.. produces an ac current/voltage its not like a temp sensor that is fed a voltage from the ecu and varies the output voltage due to resistance.. The piezo/elect. element, that is the ks, produces a voltage on its own due to vibration. it does not get any reference voltage from the ecu to vary.It is more like an o2 sensor(single wire) it creates its own voltage that is read by the ecu.. not a resistance.

 

ok I did my oil change the other day and I was listening for the VTCs and I heard a very faint knocking comming from the rear of the engine on the passengers side. when I bought this car it had a resistor on the KS. he said that it had a new KS but it needed a new wiring harness for it. he gave me the new wiring harness.

do you think I should replace the KS because its knocking or should I just replace the wiring harness and see if that helps.

 

If you have a knocking sound at idle then it's probably not detonation. Detonation or pinging will usually occur when there is a load on the engine...uphill, low RPM in a higher gear, starting off etc. I would recommend replacing the harness if it needs it but you should also find out the source of your noise. It could be a lifter (HLA) or VTC.

 

ok well it must be my VTCs. maybe just the rear one is ticking. they would only tick after about 2.5k on an oil change but I guess they tick more often now that toyota changed the filter.

 

You can get a mechanics s***hoscope for cheap from most parts stores. They can be handy for trying to isolate an abnormal engine noise.

 

can you define blown motor thats kinda vague are we talking about low/no compression in a few cylinders or developing a bearing knock or somthinhg else

i only know one person thats detonated so bad to destroyed some pistons NA it was a honda with 12:1 compresion that he never tuned and it started to burn oil really bad and when he pulled the head the pistons looked like this



i just dont see how a 10:1 engine with a well designed combustion chamber and 93oct would detonate bad enough to self destruct

 

drive it home and retard the ignition timing. I'm running a 20 degree advance with ks bypassed. I have't heard it knock or ping yet in 8 months, even this last HOT summer in albuquerque I have very good hearing and I'm always in tune with my car.

Other things can cause detonation as well, like carbon build up in the combustion chamber (causes higher compression, and possibly detonation).

From what Jeff said, I wouldn't use jwt without a ks.

 

#1 blown ring/cracked land
#2 thrown rod


To the best of my knowledge neither motor has been disassembled yet for a full inspection.

On a track only car, sure, why not... I guess, if you don't mind work. On a daily driver/street prepped car, I'd rather play it safe.

 

Was one of them matt's motor? Who had the other blown ve?

 

 

Dredging up bad memories huh.

 

Piezo element:
- no resistance 'sittin on table'
- resistance only when bending, R depends on force
- old KS bad: piezo lost its pretension. Like any Alu/Bronze metal piece would do.
- FSM: dont ever use KS element which has been dropped. (oh boy, is there one?)

ECU feeds voltage to KS, reads KS input:
- wire ok, bent piezo, some resistance, input is tied down, = NO ign retard signal
- wire broken, input is not tied down but floatin = ign retard signal
- wire ok, vibrated piezo, millisecond gaps in resistance, input is NOT continously tied down, = detonation = ign retard signal

Note: 'down' could be also up (no documentation), doesnt matter.

Bad KS cannot keep the input tied, like this

see http://www.cardomain.com/ride/748507/9

 

I don't see detonation causing a puked rod. The ARP rod bolts in my VE are IMO better insurance to keep the bottom happy than a KS would ever be. Enough detontation will break ring lands which I have seen, each in Hondas which are known for weak factory pistons when pushed anyway. If an engine was allowed to detonate until it destroyed itself I would blame that on the driver/tuner/mechanic rather than the knock sensor. The KS doesn't guarantee that detonation will be eliminated. The conditions may be as much that the detonation may exceed what pulling the timing back will resolve. Lean out a boosted engine enough once and see what happens. Carbon build up may raise the compression ratio but you also have to consider that peaks of carbon in the chamber will become hotspots thus becoming a source for preignition.

 

KS signal will tell the ecu to pull the timing back after the initial knock is heard. Thing is some ping/knock is not easily heard by the ear. You could be pinging and not hear it.

 

Detonation can cause a rod bearing to be literally beaten out of place.