Tuning JWT ECU and Knock Sensor

[DammitBobby]

GOALS: Tune the car to its full potential and keep it running longer then a week. I want it to be fun to drive on the street and 12.x times at the 1/4 mile.

MODS: JWT 72lbs, Deatchswerks 750cc, SAFCII, Zeitronix wideband with boost monitor, MSD Coil, T3/T4E .48 Turbine, AMS basic kit with ARP hardware, J30 rear end and BRM 2.5 exhaust no Cat.

Future MODS: Next week 2 12inch fans. No ETA Change the turbine housing to .63 and add Meth/water injection

I have search and found 1 statement that JWT turns off the knock sensor function. My SAFCII never shows any knock numbers. Does anybody else running this setup have the same problem?

It appears that only MSD and TurboXS KnockLight are the only other solutions. What is everybody else using and are you happy with the results?

Enthalpy tunes for 11.5 AFR`s all the way to redline with more aggressive timing. I have monitored my timing through the consult port and at WOT all the way to redline timing is set at 14. somebody has mentioned that you can send your ECU to JWT for more aggressive timing that starts boost at 14 and raises the timing up to 18 at redline. Has anybody done this and did you like the results?

What should my AFR`s be and what timing should be my goal? What about changing base timing and how much?

[KATwo40]

There's not really a set timing goal, per se. It's all about tuning for MBT (mean best torque), after establishing a proper AFR. 11.5 is ok, but I prefer to see closer to 12:1. It's been scientifically proven that MBT occurs at or near 12.5:1, so 12:1 is not out of line.

Once you establish a nice flat AFR, then you should begin tuning the timing cells for MBT. When you reach the point at which more timing yeilds no gain in torque (forget looking at hp), then you're at MBT. However, be careful as to not hit the knock threshold before reaching MBT (which is sometimes easy on our engines in stock form).

I can tell you now, it'll be tough to make the track times you want with the .48 a/r turbine housing. It will choke out enough in the upper rpm range that torque will fall rapidly, causing your MPH to be low.

As for knock detection, it would be very useful to use a good set of det cans while on the dyno. Although they appear to be primitive, they can save you the cost of an engine quite effectively.

If you have no way of retuning the JWT unit, you need to send it back to them for a reflash. Perhaps you could create a timing table and request that they please burn it. You might need to submit a release of liability or something like that, however.

[MarkEmark]

GOALS: Tune the car to its full potential and keep it running longer then a week. I want it to be fun to drive on the street and 12.x times at the 1/4 mile.

MODS: JWT 72lbs, Deatchswerks 750cc, SAFCII, Zeitronix wideband with boost monitor, MSD Coil, T3/T4E .48 Turbine, AMS basic kit with ARP hardware, J30 rear end and BRM 2.5 exhaust no Cat.

Future MODS: Next week 2 12inch fans. No ETA Change the turbine housing to .63 and add Meth/water injection

I have search and found 1 statement that JWT turns off the knock sensor function. My SAFCII never shows any knock numbers. Does anybody else running this setup have the same problem?

It appears that only MSD and TurboXS KnockLight are the only other solutions. What is everybody else using and are you happy with the results?

Enthalpy tunes for 11.5 AFR`s all the way to redline with more aggressive timing. I have monitored my timing through the consult port and at WOT all the way to redline timing is set at 14. somebody has mentioned that you can send your ECU to JWT for more aggressive timing that starts boost at 14 and raises the timing up to 18 at redline. Has anybody done this and did you like the results?

What should my AFR`s be and what timing should be my goal? What about changing base timing and how much?

I HIGHLY doubt that JWT does such personalized timing modifications...not to mention, JWT timing is based on load, not on boost (another reason I like MAP sesnors instead of an MAF)

If you are using a JWT ECU, pretty much the only thing you can do with your timing is advance it like 2* at the distributor, which actually made a huge difference in drivability and response with my JWT-ecu'ed car.

I'd call JWT regarding the knock sensor, although again, I doubt they disable this feature...disabling the knock sensor is pretty dangerous because when it does detect enough knock it makes the ECU go into "safe mode," and the whole reason JWT's are so conservative is that they don't want people blowing up their engines; a knock sensor is a safeguard (sort of) against this.

[KATwo40]

I don't know what MAF vs MAP has to do with anything I described about the tuning procedure. Yes, I'm certain they don't do such detailed tuning, as they don't have the car there on the dyno. However, there should be some linear progression in their maps, and if he's seeing 14* all the way to redline, it sounds like the map is pretty flat in the upper end. It could be a number of things, ranging from the load scale being too small (maxing out to the last high-load cell in the table before he hits full boost/torque) to just having a generic set of numbers plopped in there.

I've never heard of the ECU going into safe mode because it didn't detect enough knock reading. Maybe that's an OBD2 function? I know that I can completely disable the knock correction on my OBD1 ECU (DOHC) and suffer no consequences.

I will say, however, that running 14* at his current level is way retarded and will only give high EGT's as a result.

[Structure240sx]

my jwt ecu was hitting 14 degrees then ramping to 17-19degrees by redline, i didnt ask for anything personal jsut built motor, 72#'s and z32 maf.

i advanced timing from the distributor 2-3 degrees on top of this and kept the afr's in the mid 11's most of the time via safc

[DammitBobby]

Hey Structure did your SAFCII show knock?

[DammitBobby]

Ok let me make sure I understand you.

1st get the AFR`s to 12:1 then go to the dyno and adjust base timing until I reach MBT. The only way to adjust timing is to send the ecu to JWT.

Are you suggesting 12:1 because of the 8.8 pistons? Will that still be safe for 93 octane and Humid hot Alabama weather?

Should I adjust AFR`s to 11.5:1 until I get my meth/water injection?

[KATwo40]

With as much timing retard as you currently have, I'd say 12:1 would be plenty safe enough. The AFR I suggested isn't so much because of the 8.8:1 pistons as it is the silly 14* you're seeing. Remember, MBT is found at an AFR around 12.5:1. As the boost pressures begin to get pretty high (15+psi in this case), that AFR will need to come down, because you might reach the point at which timing retard alone will not cure engine knock. Increased charge density = faster flamefront travel inside the cylinder. So, if the density is so great that even timing retard won't cure the knock, but only promotes high EGT's, you have to use fuel enrichment to slow the flamefront speed, resulting in cooler cylinder temps and lower probability for knock.

It really comes down to what the engine wants. Some engines perform better at 12.5:1, while others want 11.8:1, despite being the exact same engine configuration.

I would request that JWT make the timing a little more linear and advanced a bit, then I'd get on the dyno and shoot for 11.8:1 for a starting point. Since you can't tune the timing, you'll have to just tune the fuel to reach for the best efficiency. The closer to 12.5:1 you can get without suffering knock, the better off you'll be. You most likely won't lose any torque in leaning out like that, and you'll only gain fuel efficiency. I'm guessing you'll end up parking it around 12:1.

What boost pressure do you run, anyhow? 12-15psi?

[DammitBobby]

Boost pressure now is around 12psi. I want to up it to 15 after I start tuning it with better AFR`s. Right now I have no knock monitor to help me. The stock one doesn`t seem to be working.

[KATwo40]

The SAFC knock monitor is worthless for actual tuning. Build yourself a set of det cans before you go to the dyno. It'll be much more useful.

Det cans can be built for less than 30 bucks. You want to get a pair of very good quality ear muffs with hard plastic outer shells.

Tell ya' what...I'll build a pair tomorrow and show you how they work. I'll post pics and all that garb. Sound good?

[DammitBobby]

Yes because I have no idea what you are talking about?

[gaehrings13]

What are DET cans......

Oh I went to pick up the pistons. Thanks a lot bobby, Im going to build another stock engine with these pistons. They look so new, even the rings and the bearings lol.

Sorry for the thread jack...

[KATwo40]

I'll build a set tomorrow and post a How To with pictures. Look for it in a new post in this section.

[DammitBobby]

Yea sad that I only had 500 miles before the other 2 pistons cracked ring lands. Glad to help you out and good luck with the rebuild.

[Florida240sx]

At 17psi in 5th gear my timign goes down to 12 degrees.......My car starts to get hot I can do maybe 30seconds of WOT and then have to wait for 2-3minutes....My timing jumps back to stock at 5500rpms goes from 15-17to 27!!!!!Trying to figure out why...MAFS voltage is at 3.7volts after 4k rpms

[KATwo40]

The scale of voltage output signal from the Z32 MAF is not linear. For example:

Let x = air massLet y = voltage

If x = y, then 2x Does NOT = 2y.

The VQ scale is not setup so that twice the flow in air mass = twice the voltage output.

[DammitBobby]

Florida have you not been able to get to the dyno yet and have Scott check out your tune? I think you might just want to wait until he can help you because I don`t think there is any sensor that is going to cause the timing to fluctuate that much. I really think you have a corrupted program in the ECU.

[Structure240sx]

i was using safcI so no knock readings with that

i eventually put on an MSD knock alert but didnt get too aggressive with it

[DammitBobby]

Do you think the MSD knock sensor is worth trying? Do you think it is worth the money?

[KATwo40]

Didn't get to make the det cans today (detonation cans). I'll be out of town for the weekend (family funeral crap) so I guess I'll make them next week.

Basically, think of a stethoscope, only much much better.

[Edub1]

my jwt ecu was hitting 14 degrees then ramping to 17-19degrees by redline, i didnt ask for anything personal jsut built motor, 72#'s and z32 maf.

i advanced timing from the distributor 2-3 degrees on top of this and kept the afr's in the mid 11's most of the time via safc

When you say 14,17 & 19 degrees, are you speaking of total timing or the map values? How many degrees retard is that?

[DammitBobby]

Base timing is set to 20 degrees. I used the consult port to look at the data and notice that it was showing 14 degrees at WOT.

[Edub1]

Please excuse the dumb question but does that mean that the overall timing is at 14 degress or that there is a map value of 14? How does one retard past the base timing where the distributor is set?

I never tuned a DE.

[pr240sx]

Another one.....what in the world is a DET can?

[DammitBobby]

The JWT ECU is programmed for a certain map that will retard the base timing to total 14 degrees. That map will be used when certain conditions such as WOT, RPM and MAF voltage to name a few are met. The consult port is just a tool that Nissan developed to monitor the ECU data.

Hopefully I will be able to get back on the project soon. I have been really busy lately with house repairs, bdays, fall festival, first block party in my neighborhood and etc. I have my fans installed but have not wired them up yet. Another issue I have run into is setting the timing light with the UR pulley. It depends on what angle you look at to guess what the base timing is set to. I really want to get this thing on the dyno but need to resolve the heating issue and brake fluid leak.

[wcbjr]

http://forums.nasioc.com/forum...41074

[DammitBobby]

My Altima fans took a crap on me a few months ago and I just now installed 2 12inch electric fans with external thermostat. My 2nd battery quit holding a charge so I upgraded it to the Red Top Optima battery.I have been driving very short trips to see if it will overheat again, so far I have had no problems. Battery is holding charge and I going to start driving to work once a week (25 miles oneway). I have since fixed a few vacuum leaks and installed a turbo gasket. Right now it appears the boost level is around 15 psi. If the weather holds out I plan on doing some more data logging and posting my results.

The boost bug is biting me again and I am wondering with this setup could I safely boost to 20psi on 93 pump gas. The weather has gotten a lot colder and I am thinking I could get away with the added boost during the winter months. What do you think I should do. I do plan on next spring installing meth/water injection kit to keep the boost level around 20psi.

[Edub1]

I'm looking at your original post again. Now I don't know what the stock DE timing looks like. But, from the description, it sounds like your JWT tune simply slamms the timing down to 14 the moment you enter WOT. This sounds to me like a real poor way to tune, done by someone who doesn't mind sacraficing a lot of performance in order to produce a safe 1 size fits all tune. My SOHC has 41* for the stock timing in WOT so you would be pulling out 27*. Enough for 36lbs if you figure .75*/lb. You also have to figure that your distributor is set at 20* so anything less than that probably defaults to 20* which is still crazy retard.

I assume you have a Z32 MAF. A funny thing happens when running this MAF with large injectors. You must correct one way for injectors and another for the MAF. The end result is that you wind up back where you started. So, you could use your stock ECU, buy a NEW BTM, tune for fuel with the SAFC and let the BTM do its thing.

If you go this route, get the new BTM with the up to 5* start point and set your SAFC with no injector/ MAF corrections and tweek. The injector MAF combo should put you within 10% of stock pulse width - lucky coincidence.

Another option is to buy a Bikirom or check out hybridka.com and do a proper ECU tune. Either way, you will probably have a lot more power at your current boost level once you get your timing straight.


Modified by Edub1 at 11:12 AM 11/23/2006

[DammitBobby]

I am just wondering if I could up the boost to say 20psi and still be safe. If so it might put me where I want to be which is somewhere in the 350 whp plus range. I agree with you on a better tune but for right now I need to get some more data logged before I can make anymore decisions. I hope to get that done this weekend.

[WDRacing]

Bobby, if you're only at 350 with 20psi of boost...I'll fly out myself and whoop your ***!!!