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I got this setup for my birthday and was wondering what you guys think about it. Here it goes, It's this black box with a switch and a reostat and 2 wires coming out of the box. This "black box" is supposed to trick the computer into thinking that the engine is at a lower tempertaure, and increases the injector duty cycle and in enriches the mixutre significally. The 2 wires are supposed to connect to one of the wires coming from the cooling sensor in series. We suspect that it will burn out the cat and we will replace it with a test pipe or a hollowed out cat. We guess that we will burn alot more gas because of the enrichment of the mixture. However this is just an on/off switch or a poor man's nos.
Junk. Skip it. Even if it works as advertised, it's still a "little black box," and a pretty un-intelligent one at that. Sell it on eBay and buy some stickers; they'll make your car even faster.
The first problem is that it enriches the fuel mixture, which is actually a two-parter. How do you know that you're not too rich already? That's really what the odds are anyway, but you want to run as lean as possible to make better power. Hondas need enrichment toys because they don't have MAF sensors. We have MAF sensors, and the ECU knows what's up when you improve VE from factory specs with CAIs and headers and stuff. Then, how is it enriching the mixture; by directly increasing injector pulse width, or by just tricking the AIT segment of the ECU into thinking that it's 50*F outside? Either method is bad, because the ECU will see that it's adding too much fuel (watching the O2 sensor), and try to dial it back. Then you have the dual of the black boxes, and nobody wins.
Secondly, even if this product does work, it's likely not going to do any damage to your cat. Cats generally burn up and crack from running waaay too lean or become clogged by running leaded fuel. The most common cat death on SE-Rs looks to be people who stand on the rev limiter, actually. SR20DE ECUs tend to cut spark, not fuel, so when you do same, you start spewing unburned fuel at the cat element (no spark means unburned fuel, get it?). Then, when you get off the limiter, the exhaust gasses from spent fuel rush towards the element, igniting the unspent fuel, which burns and generates surface temperatures too hot for the element, element cracks, BAM! cat failure.
It also seems that you should do some research on cat technology as it applies to Nissan products. You ABSOLUTELY SHOULD NOT run cat-less on a naturally-aspirated car. Removing the cat and placing a test pipe shows no positive effects on dyno charts, and running a hollowed cat shell actuall reduces power because it's a turbulent disruption. If your cat is already bad, replace it properly with a $99 Catco universal with 2.5" inlet and outlet (very similar to Nissan cat). Nissan did a good job, don't screw it up.
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Why would you want to lean the mixture out?? Please explain more. By the way I got this thing for free for a guy who races and he said it works so I figured I give it a try. So I didn't waste money on it. Also does anybody know what kind of injection system that the sr20de has or uses.
Because most ECUs are tuned to keep the car rich, especially under WOT conditions. The excess fuel acts as a combustion chamber coolant, which keeps detonation at bay, which reduces warrantee claims. It only makes sense. To make more power, you actually dial fuel out, which increases combustion temperatures and increases power.
Hondas with mods, like I said, need fuel enrichment because their ECU doesn't know how much air is actually coming into the engine. You put a CAI on a Honda so that it sniffs better, then put a header on it to improve scavenging, and the Volumetric Efficiency goes off of the charts. The Honda ECU, meantime, is only sending the stock amount of fuel, which makes it lean, and power goes up quite a bit, relatively speaking. Then, at some magical but undetermined point, they start going too lean, and you need to start adding fuel again, which is pretty easy to do with a black box Toys like this sort of work on Hondas, because the ECU isn't too bright to start with. Because we have Mass Air Flow sensors, and the ECU actually monitors what goes into the engine and adjusts fuel accordingly, toys like this don't generally work. When they do work, the O2 sensor tells the ECU that something's wrong, and you have trouble. Additionally, the Nissan ECU learns pretty well about it's environment. You don't want to interfere with that.
You said he races...what does he race? Bikes? Chickens? The fact that some monkey can pilot a 600 HP car in a straight line for 1400 feet says nothing about his ability to tune an engine. No offense to you or your friend, but you can't be so naive about those from whom you take your advice.
It's a gasoline injection system, as opposed to a diesel injection system. Please narrow your question down, or at least make it multiple choice.
He races a classic se-r and he doesn't drag race it, scca to be excact. The direction manual says that it's more noctiable with a heavy to middle modified car, like race accplacations. But the guy I got it from said that it will work if you dont have any mods but more benefical to have more mods. Heres what the install prodecure says. The " Fuel Box" installation is very simple. First you must isolate the coolant sensor that has input to the L-Jetronic Computerq. (does the SR20de have an l-jetronic somputer???) Cut one wire on this sensor lead, and make a series connection with your "Fuel Box" using butt connectors or soldering. Then your done. So my question was stated does the sr20de have a l-jetronic computer?? But leaning out the car isn't going to gain you any thing if you have alot of mods ex: cams header, CAI, bigger valves, higher compression. Does the MAF or ecu add more fuel when you have more mods??
I'm going to fly the bullsh*t flag on whether or not it works on Nissans. Show me a dyno chart if you want to pursue this any more. It's monkey logic, and it's going the wrong way.
No, L-Jetronic is a Bosch fuel injection system, and Nissan doesn't use Bosch fuel injection of any generation, at least not in the cars we're concerned about here. The install is simple enough, but the whole idea is functionally backwards. If you want to know why leaning out the fuel mix makes more power, learn how internal combustions with gasoline work, and re-read my post above.
Stock engines are already tuned for too rich, from the factory, to keep the engine safe (rich is safer, lean is dangerous due to risk of detonation). It doesn't matter how many mods you have, the MAF sensor always tells the ECU how much air is coming in, so the ECU always adds at least enough fuel to make a Stoichiometric balance (14.7:1). At WOT, this number quickly approaches 12:1, which is bad for performance; you're practically drenching the cylinder walls with fuel by that point (not really, it's a slight exageration). To get "free" horsepower with a stock or non-stock engine, dial back towards 13:1 or 13.5:1, which makes hotter combustion, which makes more power. It also tends to lean towards detonation, but only if you're an idiot about it and fail to use proper tuning techniques. Several SE-R people have installed adjustable fuel pressure regulators and reduced rail pressure from 43 PSI to a pressure in the mid-low 30's and claimed to feel significant SOTP improvement. Some have shown dyno charts with up to 4 HP gains from fiddling with fuel pressure alone. This is good tuning, and the theoretical physics behind it are sound. I have no problem believing 3-4 WHP gains from going leaner.
This toy is bunk, though. If this toy does what it says it does, and does an effective job, you should be wandering even more rich, like 11.5:1 or maybe even 11:1, which is actually detrimental to your performance. Again, if you can show me before-and-after dyno charts, complete with wideband O2 readings, I'd be more than happy to eat my hat.
Ok, the fuel map wont work for our cars because we don't have L-jettronic systems. But making the system leaning is about the dumbest idea I have ever heard. Why on earth would you lean out the system. The more gas in the cyclinder means bigger the boom. The less gas you have in there the less boom you have. I would like to see the dyno charts saying that leaning out the engine will increase horsepower. Also, why do you think cars and or some race cars (SCCA, HSR...) have gaint carbeurators on obivously to get more gas into the engine so they could go faster. What you just told me makes no sense at all.
Originally posted by fatboyz921 Ok, the fuel map wont work for our cars because we don't have L-jettronic systems.
Wow.
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But making the system leaning is about the dumbest idea I have ever heard.
Then you need to go out and do three things:
Learn how gasoline internal combustion engines work.
Learn how OEMs like Nissan tune for safety.
Go spend some time with a carbureted engine or a programmable EFI system on a chassis dynamometer with a wideband O2 sensor and play around.
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Why on earth would you lean out the system.
This makes the third time I've told you in this thread. The closer to Stoichiometric you get, the more efficient it burns, which makes the most power, to a point. The problem with being at Stoich (14.7:1 on pump fuel) and at WOT for extended periods tends to cause detonation, which is why the OEMs don't do this from the start. Have you noticed that nobody like Andreas or Charlie has stepped in to correct me? Notice that they're not defending you? I'm quite right about what I've said. You need to learn about it and stop arguing about things you don't understand.
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The more gas in the cyclinder means bigger the boom. The less gas you have in there the less boom you have.
Wrong on both counts. The more fuel you have, the harder it is to combust, thus making less power. The less fuel you have, though, the easier it is to combust, which also makes it a detonation hazard. You clearly understand that it takes some fuel to burn, now go figure out how MUCH fuel you need to burn at a time, and then you and I will be on the same page.
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I would like to see the dyno charts saying that leaning out the engine will increase horsepower. Also, why do you think cars and or some race cars (SCCA, HSR...) have gaint carbeurators on obivously to get more gas into the engine so they could go faster. What you just told me makes no sense at all.
All you have to do is look. I just came off of a ten-hour shift, and I can barely read, or I'd go show you a few. Hondas are a notable exception (MAP-based systems suck at despensing fuel on N/A applications), but Nissans (especially JWT tuned ones) are a prime example of how much power there is to be harvested. Giant carbs are not just to get massive amounts of fuel in; they get massive amounts of air in, too. If all you needed was lots of fuel, a 375 CFM Holley two-barrel with jets the size of soda straws would work, wouldn't it? It doesn't work that way. Go take a chemistry class.
Okay, I've found a few things to look at that illustrate at least two of my points, though there aren't before-and-after results to show you anecdotal evidence of why I'm right. Check these out:
Pay special attention to the ones with A:F/R fields. See how Nissan ECUs go WAY RICH at WOT, especially in the upper RPM bands? A gauran-damn-tee you that with an adjustable fuel pressure regulator to back some of that camel piss out, they'd pick up horsepower like you wouldn't believe. If they dialed in to about 13:1, it'd be pretty safe, too. Nissan just errs on the side of excessive safety. And OPEC likes it that way, too.
As far as learning to tune for power and safety, just use Google and search for S-AFC. Lots of data out there, you just have to look. I just wasted 30 minutes pouring over megabytes of text concerning keeping the O2 levels right for making power in DSMs, Hondas, and Saturns, of all things.
Last edited by CowboyDren : 11-05-2002 at 09:27 PM.
You ABSOLUTELY SHOULD NOT run cat-less on a naturally-aspirated car. Removing the cat and placing a test pipe shows no positive effects on dyno charts, and running a hollowed cat shell actuall reduces power because it's a turbulent disruption. If your cat is already bad, replace it properly with a $99 Catco universal with 2.5" inlet and outlet (very similar to Nissan cat). Nissan did a good job, don't screw it up.
