Black LS1 T/A

Yeah, daking350. This is the way LS1's get their LTFT's computed, as well.

It is also important to note (in case someone is not aware) this is not relevant to WOT conditions. The computation of LTFT's takes place during idle and cruise conditions to maintain near perfect A/F ratio while driving.

If your ECM works like our PCM, the LTFT computation is suspended when you floor it and LTFT's acutally zero out IF your LTFT's were near zero or slightly negative (indicating a slightly rich condition). If LTFT's were slightly positive from a slightly lean condition at cruise-time (we have some debate on this in the LS1 community), more fuel is added based on the pre-calculated lean condition indicated by the positive LTFT's above and beyond the primary multiplier for Performance Enrichment per RPMs (PE/RPM).

Since we have the capability to adjust the PE/RPM table (which is the multiplier table that adds fuel at WOT as we increase in RPMs), we LIKE "zero to slightly negative" LTFT's while cruising, because we can more consistently control the A/F mixture throughout the RPM range.

In most of us (not all) experience, if LTFT's are positive and fuel is added on top of the PE/RPM multiplier, it is not always consistent how much fuel it adds.

Also, remember, from your very good documentation, individual engines, wear and other environmental conditions cause a variance in the LTFT. (Remember my statement about cool morning air and mid-day heat? Also, humidity seems to play a factor.)

What's more, while our stock O2 sensors are excello-mundo at idle and cruise, they are not very good at all at WOT. So calculations coming from the narrowband O2's at WOT, while providing some idea of relative leaness or richness, are not very accurate at all.

The kind of info you posted will be great when someone comes up with a way for you guys to fine-tune your vehicles' ECM. Cool stuff!

Black LS1 T/A

Now.. you just showed a LOT of wisdom when you spoke here.

I've found that when I put on a smile and am amiable, I get a lot more results than when I start out belligerent and hostile.

Of course, if a vendor is intransigent, there is always belligerent and hostile.

But, yes, try the sugar before you apply the vinegar.

Black LS1 T/A

I saw this in another sticky post, and thought I'd bring this up in the discussion. It never occurred to me guys running FI would question ATI's recommendation to use copper plugs.

Thanks, 350Zzzz, for bringing up something that was an oversight on my part as a discussion piece:

I just stepped into this thread and haven't read it all.
But, I want to jump in on this spark plug issue right away.

You guys had better take ATI's recommendations seriously and not cut corners.

Platinum tipped plugs (which come in our LS1 cars stock) are fine as long as you're not running a supercharger/turbo/nitrous because the tips get hot and stay hot. However, this characteristic can lead to pre-ignition.

Detonation is the BIG, BIG enemy of Forced Induction. If you are running platinum plugs on your supercharged application, you are courting danger. It MAY actually account for some people's detonation in the upper RPM range.

You need COLDER, copper plugs if you are running a blower.

Again, temper this with the fact I am speaking from the LS1 world. But, if ATI recommends it, it is for a reason. And I KNOW the reason from our LS1s' perspective.

-----

Also, let me mention you stand a risk of your spark blowing out if your car has a naturally wide spark plug gap and you leave it that way. What is your spark plug gap? Do you guys decrease the gap on your boosted applications?

Black LS1 T/A

Hi, John -

Have you approached any of these guys about trying your unit out? I still think if the base ATI kit is getting detonation, they need to look long and hard at what might be causing it.

But, guys that increase boost or rev it up higher or add other mods may need some timing customization capability.

GaryK

We're already there

I have it on my car now, and its working great. Still fine tuning it, been too busy with the upcoming holidays to really concentrate on it.

John at J&S

We've got a few in the pipeline. GaryK and N4Spd were the first to get their's installed.

I hear Gary's getting good feedback from the knock indicator, showing him what to do with the other controls. I expect to see the dancing banannas on his posts soon.

daking350

I dont get it...So it shows him that he was experiencing knock??

John at J&S

The system detects the onset of inaudible knock. Knock that a tuner wouldn't even know was there, then zaps it before it becomes audible. At the same time, the Status LED glows in proportion to the amount of knock retard, to guide you with your tuning. If you have one of our bargraph displays, you can see how many cylinders are being retarded, and by how much.

Here's a link to a post from a Subaru guy, who had doubts about how well it would work on his 2.5RS Subaru engine. His J&S unit had RPM retard, but no boost retard. Note that he disabled his FMU(???), and turned off the water injection:

http://forums.nasioc.com/forums/show...hreadid=113975

Black LS1 T/A

Does the 350Z have Knock Retard capabilities like our LS1's?

GaryK

I got my bargraph display built yesterday, now I just need to figure out where to mount it. Woohoo!

Up until now, I have been using the single led to see what the J&S is doing. You can tell a lot just from that. I did try it with no boost/rpm retard whatsoever, and found that from time to time it picked up some knock well before I would ever be able to hear it. I have never really had any audible knock, but seeing what the J&S was doing shows that it is borderline without proactively retarding the timing. I'm now running some boost retard, and with my current settings it never picks up any knock at all. By the seat of the pants, it doesn't seem to have lost any power, but the only way to truly know is to dyno it.

John at J&S

Black LS1 T/A:

Don't know how much range of authority the control system has, but we tap the 350z's factory knock sensor.

elektrik_juggernaut

Black LS1 T/A.......i owe you an apology.......your frequent visits have shown to me that you are indeed here to help..........please forgive my suspiciousness, i just have plenty of reasons to suspicious of ATI.......i don't want to get into the details again, just know that i have my reasons.......so i'm in the vinegar stage at the moment

On that note, some believe that our stock Knock Retard cuts off at about 3500 RPMs.....not sure if there's any proof of that.......this is how it is in other imports........the reasoning for this is that the Knock Sensor cannot discern between normal engine noise and true knock at RPMs above 3500

12SecZ

noise or also vibration.

John at J&S

According to Shiv, the 350z's knock control is active under all conditions that knock might be expected.

The Subaru ECU ignores the knock sensor above 5000 RPM. The guys on the 3000GT forum (3si.org) think that the knock sensor is ignored above 3500 RPM.

It's not that hard to check. Tap on the sensor with a small wrench or extension, and see if it retards. We ignore the sensor until the vacuum drops below five inches and the engine exceeds 1750 RPM. The factory systems might do something like that, too, so you might have to do it on the dyno.

Black LS1 T/A

It's all good, man. I'd have the jitters, too, if I was afraid I might lose my engine.

Our knock sensors are definitely active throughout. I've had my 422 as high as 7200 (not intentional, but it should be safe even to 7500... it just won't make the power there at my boost level) and it will retard if there is knock.

Gary, some of the old racers say a bit of inaudible knock actually means you are at peak performance. The reason many of us try to knock it down to zero is because of the way we can be knocked down into the Lo-Octane Spark Advance tables. If we go into too much Knock Retard too often, a different table with lower timing values gets used. Depending on the variance between the two tables, power can get kill quite a bit... more than necessary, even.

It's good to have, becaues bad gas (or the scoundrel that puts in low-octane gas ) could kill the engine if they WOT it with the timing set for premium fuel.

Black LS1 T/A

Another thing... because (Knock Retard) KR is always on, many have tried to find ways to desensitize them to avoid the retard induced by false knock. The last release of LS1-Edit, Carputing added the ability to adjust various parameters that affect KR learning, the noise floor, attack, etc. So I listen carefully for audible knock. If I get 3 degrees or so of KR and don't hear any detonation, I raise the noise floor a bit to avoid false knock.

This KR at all RPMs may actually have cushioned us LS1'ers better from messed up engines than you guys would be. Interesting.

Black LS1 T/A

John, if their KR is disabled at the upper RPM range, will your device do anything where it is most needed since it goes off the stock Knock Sensors? Is there a way to verify where (if it does) the 350Z Knock Sensor takes a vacation?

Oh, wait... <slap head> of course, you said you read the sensor... you're not just modifying the ECM's KR algorithm. OK.

The sensor is not going to stop sensing... it's just that the ECM MAY ignore the sensor's output, right?

12SecZ

What is the direct link to that 32 ounce can Black LS1 T/A

I can't find it but want it. I just see gas not addictives. Thanks!

350Zzzz

For every degree of timing that is pulled from the engine it is estimated that you lose 5 hp; in the event you apply 10lbs of boost and pull 8-12 degrees of timing out the power lose could add up to 40-60 HP

Timing retards are more useful for those who boost above 7 lbs., but that doesn't mean that it will not benefit the daily driver. However, the daily F1 driver has to also consider other factors, such as AF ratios, fuel pressure, injector sizing, fuel octane, efficient intercooler, oil cooler, coolant radiator, spark plugs, etc.; reaching the flash point of your fuel mix through compression is another issue to contend with.

It would be a misconception and tragically foolish to believe that only with a “timing retard” control unit, detonation will not be an issue with F1 systems. In which case, even if F1 manufacturers package a knock sensor it will not guarantee that the engine with not be opened to detonation. Remember, most foreign engines are already running at a pretty high compression ratio.

XBS

iTrader: (29)

Wow just read this whole thread, very informative, BlackLS1 you definetly are one cool guy coming over here to share info, hopefully you keep posting here so i can learn some more before i go FI,