Grace_Imports

iTrader: (1)

I think if a car was pinging hard enough to beat out the rod bearings or break pistons (even Honda) that you would hear something; it wouldn't be a subtle ping. I think that you would get a rod knock before it spits it out so even if one doesn't have a trained ear if they heard an abnormal noise then they should back off the loud pedal until the source is determined. I think it really takes a lot to make a V6 Nissan pitch a rod. (old Volvos too)

internetautomar

iTrader: (30)

some people just turn up the radio

Grace_Imports

iTrader: (1)

I know, I just don't get the folks I see driving around with their cars pinging to heck . Well it's more business for me if they break it I guess...

CandiMan

iTrader: (1)

Which raise dome piston is this?

MrGone

iTrader: (30)

10.5:1 VG30DE pistons

valz23

iTrader: (1)

Can you explain??? You mean you're glad you can adjust it if you hear a knock? You still have to hear it on time, if your exhaust is loud enough, you'll never here it unless you're sitting in the traffic, or something. How else would AFC protect you? I had both the original AFC & S-AFC, unless they changed it big time... I mean, if you don't know what you're doing, AFC would be way more dangerous than JMT ecu, don't you think? But if you know what you're doing, and have a way to tune your car, why would you want a JMT at all? AFC is cheaper, too.
By the way, I was just going through the russian maxima site, there is a guy that installed a knock sensor from a russian car (I still don't know why there was a KS in the russian car???) in his Nissan. It took a little modification, but it worked. I'm sure it's possible to change the location, too. I don't see why one would want to just bypass it?

MrGone

iTrader: (30)

The SAFC-II allows you to monitor engine knock. It will not actively do anything about it thats up to the driver. According to lanedrifters JWT pretty much disables the "safety" maps for when the ECU detects engine pinging/knock from the knock sensor.

Benefits with the JWT over the SAFC-II are increase redline and advanced ignition curves. The SAFC-II allows you to completely customize your fuel trim to your car and still retain the 'safety' map.

If I were to buy anything today it would be the E-Manage Ultimate.

valz23

iTrader: (1)

I didn't know that it allows you to monitor engine knock now, in the original AFC all you could do was to adjust the A/F ratio at several different RPM points. The first S-AFC was pretty much the same thing, but digital. I never paid much attention to the 2nd one, since I thought it would be pretty much the same thing, but more expensive. It's pretty cool, that it has this knock option, deffenatly worth an extra $100.
Sorry, I was thinking about something else when I said e-manage

valz23

iTrader: (1)

Yeah, I was thinking of a AEM EMS. That's about as much control as you can get. Man, I haven't paid attention to this stuff for 2 or 3 years, and so much changed. I was just looking on the internet, there is so much new stuff out. It's getting easier and easier to mod your car, nice. Makes me wish I was 18 again. Oh well, may be one day, when I retier, there'll be nothing better to do than to travel and build cars.

Akuma2001

I called up JWT and they said that they lean the mixture and adjust the fuel curve for better throttle response. That's probably why the mileage was better.

valz23

iTrader: (1)

would leaning the mixture really give better throttle response? How would one have anything to do with the other? Anybody?

Akuma2001

I mentioned two different things.
1. They lean the mixture(which would allow for better fuel mileage)
2. They adjusted the map for better throttle response

MrGone

iTrader: (30)

yes


you have a faster, more efficient burn.

MrGone

iTrader: (30)

it's the function of the same thing


Also when we/they say lean, it does not mean actually making the engine run on a lean condition. They are just "leaning out" the fuel maps (reducing the ammount of fuel being dumped into the engine).

valz23

iTrader: (1)

I'm sorry, I thought you meant both of them together. But still, isn't it a part of the same thing? Fuel map is a map of A/F mixture at different RPMs, isn't it? Correct me if I'm wrong. I see what MrGone is saying, quicker burning would insure quicker trotle response, but wouldn't you loose the power at the same time? I mean you can make it more effficient to a degree, but wouldn't this undo the whole golden rule: more air+more fuel=more power??? There are plenty of other ways to get better trotle response, like lightening the rotating mass. Am I right?

subs1000w

your missing the point so let me try to explain basicly the factory nissan fuel maps are way to rich so jwt leans them out to make the best power but not overly lean

factory nissan WOT maps are in the 10-11:1 A/F ratio (strictly for safty)best na power is made around 13:1 so thats roughly where jwt sets them overly lean would stoich 14.7:1 get it now ?

505max94se

iTrader: (15)

Sort of...

It's true if you have if you have more fuel AND more air you get more power, but the mixture needs to be correct (or stoicheometric, bad spelling). With an na car like the maxima, you can't really add more air (without fi) so you wouldn't want to add more fuel because it'll run rich and it'll lose power and efficiency. Maximas, from the factory run a little richer than the should, so if you "lean" out the afr you'll get more power and efficiency. The key is proper mixture of air and fuel. Theoretically, as long as you keep this proper mixture you can add as much air and fuel as you want and create as much power as you want (there are other factors that play a role here so it's not really realistic).

MrGone

iTrader: (30)

In laymans terms, yes ... well, kind of. Right idea, I'm just being picky

Again, in laymans terms, the A/F ratio is really just a value in a function. Basically the ECU says I have X ammount of air so I will need Y ammount of fuel to achieve a perfect burn (Z).
You get X from the MAF
Z is your answer
you solve for Y

so in this case, my MAF tells me I have 1 part of air so I will need Y parts of fuel to achieve a 14.7:1 burn. I will need 14.7 parts of fuel to have a stoich or complete combustion.

Now you have to account for outside factors that affect how an engine performs, these are accounted for in the fuel map. (engine temp, intake air temp, knock, and more all affect the burn so they are used to help accurately determine how much fuel you will need to achieve a complete burn. There is also open loop and closed loop, but just ignore that for this.

If you go above 14.7:1 you have leftover or unburned oxygen, so you are not making as much power as you could be. Remember this is all on paper, when you are actually tuning an engine you always want to burn as much fuel as you can, so you dont want to have too much, but you also do not want to have too little. You do not want to run an engine at 14.7:1 (stoich), instead you want to shoot for roughly 13.5:1. Running rich also allows for a more ideal air-fuel saturation but really the main reason to tune rich is because the ECU is not instant, it needs a small buffer. It is also using a narrowband O2 and not a wideband. There are also other factors which the ECU cannot compensate for ... outter cylinders are going to run slightly cooler because of the air flowing around the block, coolant flow, sometimes the nature of the combustion chamber/flame path/etc has an effect which is not calculated, fuel quality, really a bunch of small things that make itty bitty differences. The only way the ECU can compensate for these is to have more sensors (EGT on each cylinder, WB O2 on each one, etc).

There are also different ways to get readings, like the ammount of air for example. You can use just a MAF, MAF + IAT, MAP + IAT, MAF MAP and IAT, etc. The more sensors you have the more accurate you will be .

sorry if that jumps around abit, I kept going off on things and had to come back lol.

Think of it like this, say Nissan tunes the cars to run at 12.8:1 from the factory, you can lean it out to 13.5. It's still running rich (unburned fuel), but not as much unburned fuel as 12.8:1.

Also those numbers are just for reference.
too much typing

valz23

iTrader: (1)

As I was saying, to the point, they say the optimum mixture is at around 13.7:1, but then again, there is a reason why Nissan is running it lower-they're trying to keep it safe. So, unless you were running on a race track, you can only adjust it so much. I guess what I'm trying to say is, does the amount of adjustment you can make in A/F mixture, make enough difference in making your trottle response much quicker? Fuel economy - yes, but as one of you said, you can't run it stoich, and that's when you would get the real difference.
Anyways, I think I'm just walking around in circles. The way I've seen a lot of people run their turbo cars is, using some kind of piggy bank controller, but still have their ECU redone to have the red line,etc. changed. I really don't think that reprogrammed ECU can do much in trottle response, at least not as much as lightening the drivetrain can. Again, this is my opinion, I'm not trying to say I'm a specialist tunner, or something.. When it comes to my cars, I always figured everything out on my own, and it's nice to get some feedback, especially from the people who have done some work theirself.

valz23

iTrader: (1)

I guess I missed the point again completly. What I'm trying to say is "quickening the trotle response" isn't the best reason to name for making leaner a/f maps. Making horsepower is, and etc. But to get the better trotle response one should work on his drivetrain. Does this sound better?

Grace_Imports

iTrader: (1)

IMO the closer you are to stoichiometric then the better response you should have as well as the other gains (power & economy) . "Lean is Mean" as long as you aren't too lean.

lanedrifters

iTrader: (4)

The way the fuel maps are layed out, you have an rpm scale and a "tp" or load scale so you can adjust not only wot conditions but all load conditions, you also have a acceleration enrichment which is based on speed of throttle opening, so you can tune for better response and better mileage at cruising loads and wot runs. The jwt fuel map I looked at(which is at least 4-5 years old) was significantly richer than the stock fuel map in the higher load / high rpm section. Ill have to recompare them as its been a couple of months since I looked at it.

Grace_Imports

iTrader: (1)

I've got 2 VE knock sensors laying out and both of them have 2 wires. I think that there would have be a reference voltage going from the ECU thru the KS and back to the ECU. When the KS gets a "tingle," it would "bend" the voltage signal going back to the ECU. By putting a resistor in place of the KS to bypass it, you are putting a resistance "on the table." The ECU is not reading the resistance but is reading the voltage which has been "bent" by the resistor. The voltage would pretty much be a constant with a resistor in place. You would thus select a resistor that would send the desired voltage signal back to the ECU that keeps the ECU happy.

lanedrifters

iTrader: (4)

Wrong, there are 2 connections on the knock sensor but 1 connection is not used. One wire is connected from ks to the ecu (white wire). The other wire is just shielding which is connected to ecu ground, but not to ks. When the ks get vibrated or "pressure", it creates a 20mv-600mv (or so ) signal at different frequencies (thats why shielding is needed, for the low voltage) the ecu uses a circuit to convert the ac signal to dc (bridge rectifier) as well as an a/d coverter etc. to determine a digital pattern to the analog signal. Then depending on frequency and amplitude , the ecu can pick out whats knock , to a certain extent.

Thats also the reason I cant understand how the resistor method is working at all, I believe it is just allowing a stray voltage to enter the system with limited currecnt flow which is probably just enough to satisfy the ecu into thinking the ks is still active. Although it may not be precise or functional all the time.

Take a look at the fsm and youll see the shielded wire setup. Alos this page is for a Neon but its the best explanation of a knock sensor I could find on the web quickly with the same type of knock sensor.:Autozone

Wiking

As a digital device, 'any' ECU pull up/down R will change/lock logical state. Thereby FSM cannot give any explicit value, but states that workin KS "has to have resistance".

The second wire, shield, represents logical zero.