JWT ECU and Knock Sensor thread split
10-24-2005, 01:05 PM
#2
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.
http://maxima.gregg-henry.com/grace_imports/
here are all the pics youve sent me.
10-24-2005, 09:30 PM
#3
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)
Originally Posted by Brad92SE
Engine looks great!! Regarding the knock sensor, everyone is gonna say its a bad idea, but I ran mine bypassed for a couple months N/A and for about 8 months while FI, and I haven't had a single problem. I have even overboosted the engine once and nothing broke (luckily 
). As long as you don't push the timing too far and keep good gas in it like you said, then it should be fine. I can't wait to see some dyno numbers!
). As long as you don't push the timing too far and keep good gas in it like you said, then it should be fine. I can't wait to see some dyno numbers!
10-24-2005, 09:40 PM
#4
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.
The build looks delicious, BTW. I wish I could put that in my car.
10-25-2005, 04:55 AM
#7
Originally Posted by 505max94se
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)
10-25-2005, 05:09 AM
#8
Originally Posted by tripleGmax
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...
10-25-2005, 06:59 AM
#9
Originally Posted by MrGone
after having a SAFC-II hooked up I would not bypass the KS 
especially with an increased CR, but thats just me
especially with an increased CR, but thats just me
10-25-2005, 10:00 AM
#11
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.
Originally Posted by lanedrifters
Why not, all with JWT ecus are running without any timing or fuel knock maps anyways.. 
10-25-2005, 10:05 AM
#12
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.
10-25-2005, 10:08 AM
#13
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.
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.
10-25-2005, 10:15 AM
#14
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.
10-25-2005, 10:50 AM
#15
Supporting Maxima.org Member
Join Date: Jan 2002
Posts: 3,371
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
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
10-25-2005, 11:13 AM
#17
Originally Posted by lanedrifters
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?
10-25-2005, 03:19 PM
#18
Originally Posted by lanedrifters
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.
Also seeing as JWT has not released their bin files, you can forgive me for being skeptical.
10-25-2005, 03:21 PM
#19
Originally Posted by Jeff92se
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.
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.
10-25-2005, 03:26 PM
#20
Originally Posted by MrGone
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.
Originally Posted by lanedrifters
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.
Hot day, loading it at low rpm, no ks protection, crap 91 octane, going up steep hill, jwt ecu = ouch
10-25-2005, 04:32 PM
#21
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 
10-25-2005, 04:35 PM
#22
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
BTW if you havent seen these site yet:
ZTECHZ
ECCS Tuning
Youll also find links to other nissan ecu sites as well from these
10-25-2005, 07:12 PM
#25
Originally Posted by lanedrifters
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?
10-25-2005, 07:19 PM
#26
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.
10-25-2005, 07:27 PM
#27
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.
do you think I should replace the KS because its knocking or should I just replace the wiring harness and see if that helps.
10-25-2005, 08:07 PM
#28
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.
10-25-2005, 08:44 PM
#31
Supporting Maxima.org Member
Join Date: Jan 2002
Posts: 3,371
Originally Posted by MrGone
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
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
10-25-2005, 09:04 PM
#32
Originally Posted by tripleGmax
if your ks is bypassed then what do you do if you hear pinging......
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.
10-25-2005, 09:07 PM
#33
Originally Posted by subs1000w
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
[img]http://www.ba-f-body.org/photos/flame/piston1.jpg[img]
i just dont see how a 10:1 engine with a well designed combustion chamber and 93oct would detonate bad enough to self destruct
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
[img]http://www.ba-f-body.org/photos/flame/piston1.jpg[img]
i just dont see how a 10:1 engine with a well designed combustion chamber and 93oct would detonate bad enough to self destruct
#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.
10-25-2005, 09:15 PM
#34
Originally Posted by MrGone
#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.
#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.
10-26-2005, 09:39 AM
#37
Senior Member
Join Date: Dec 2004
Location: EU Scandinavia
Posts: 4,323
Originally Posted by MyGreenMax94
Dredging ...
- 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
10-26-2005, 09:55 AM
#38
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.
