[PHeller]

If the auto ECU doesn't cut fuel when decelerating, does it cut fuel when the clutch is pressed in? I can't imagine the automatic ECU dumps fuel all the time, so there has to be a state where it cuts fuel, right?

I'm not interested in tuning as much as I am in getting a better ECU to replace my stock one that might have issues. Speed limiters are pretty annoying too, especially when connected to rev-limits.

Again, I have no interested in any ECU over $40 bucks, so lets talk Stanza vs Auto vs Manual KA24E ECU.

 

[mikethebiker]

so lets talk wtf are you talking about?

all those ecu's are going to cost the exact some thing, assuming you were to get them from the same place. only way youre going to find a better price is if its a deal somewhere, like a junkyard. and i guarantee your not going to be hitting that 115mph speed limiter anytime and if you are you shouldnt be. a stock 240 barely wants to go over 120 just because it has no hp and shitty aerodynamic properties.

Im comparing the maps right now. The manual is way richer up top than the auto. The timing only varies a little in the part throttle mid rpm range.
Oddly enough the k value is slightly different as well as the latensy which may actually offset the differences im seeing in the fuel maps.
The maf translation
the fuel load scale
the min pulse width
and the tp load limit are different as well.

The manual ecus are programmed to actually cut the fuel when decellerating in order to save fuel. The auto one cannot do this because the engine will die.

 

[nissanfreak8]

If the auto ECU doesn't cut fuel when decelerating, does it cut fuel when the clutch is pressed in? I can't imagine the automatic ECU dumps fuel all the time, so there has to be a state where it cuts fuel, right?

I'm not interested in tuning as much as I am in getting a better ECU to replace my stock one that might have issues. Speed limiters are pretty annoying too, especially when connected to rev-limits.

Again, I have no interested in any ECU over $40 bucks, so lets talk Stanza vs Auto vs Manual KA24E ECU.

The auto ecu never cuts fuel while the key is on, I mean think about it what happens when you run out of fuel with an auto car. The engine stops, where as the manual will keep the engine spinning until the clutch is pressed in. IIRC when you let off the gas in an auto the computer goes automatically to is idle mixture so the engine doesn't stall but you won't keep accelerating. Where as the manual ecu does the same thing but has a stepped up idle until a certain speed when slowing down. When you come to a stop then the idle mixure is returned to idle. At least that was how it was explained to me by the local nissan dealership.

 

[PHeller]

Is any of that noticable when swapping ECU's? Many people have interchanged the two ECU's but most people never mention any changes in "drivablity".

Let me get this straight:

Automatic ECU on Manual Transmission
- Starts normal, slightly rough idle (sometimes)
- Will go a bit lean at higher RPMs (better for power)
- When clutch is pressed, RPMs drop slower (Post on NICO explained this)
- During throttle-off, car decelerates faster (can't figure this out?)

It's that last bit that I'm interested in. That and the differences the auto and manual stock tunes effect MPG.

 

[nissanfreak8]

The deceleration is simple, the ECU automatically goes to the 750 rpm preset instead of the programmed stepped idle the manuals has. And actually from what I have read, the KA likes a rich fuel mixture better than a lean, granted I don't know what the acutal numbers are for either map. As far as MPG I would say you might notice a mile difference depending on how you drive, probably more city and higher speed freeway driving. The mpg I don't really know on tho.

 

[mikethebiker]

NA in general likes it to be richer when WOT for best power

 

[4x4le]

Give me a few seconds and Im going to compile some screen shots comparing the auto ecu tune and the manual ecu tune.

The deceleration is simple, the ECU automatically goes to the 750 rpm preset instead of the programmed stepped idle the manuals has. And actually from what I have read, the KA likes a rich fuel mixture better than a lean, granted I don't know what the acutal numbers are for either map. As far as MPG I would say you might notice a mile difference depending on how you drive, probably more city and higher speed freeway driving. The mpg I don't really know on tho.

Its a little different than that.
On the manual ecu it "cuts" fuel and retards the timing as to not detenate. People see on their widebands that the fuel is "cut" but thats just because it is insanely lean. There is still a minium pulsewidth (which can be changed if you have the ability to tune) value set there in order to keep the cat hot for emissions purposes (which is stupid because no fuel should mean better emmissions for me, emissions is a hoax but thats another discussion)
Anyways, the auto ecu cannot do this because the engine is not directly connected to the tranny in the same way a manual is. If the engine is to loose power it will stall.

The ka in n/a form dosent necessarly "like" to be ran excessivly rich in order to make power, thats just something nissan did to ensure the safty of the engine. You can actually pull a good chunck of power out of a stock ka without even touching the timing by doing nothing more than leaning out the wot afr a little. Plus that will get you better fuel economy when your playing. As soon as get a better clutch that dont slip im goign to tune my daily driver (ka24-e) for a few reasons. 1, it runs freaken 10.5:1 afr at wot which is insanely rich, expecially for a n/a! I should be able to pull a good 10 hp out of it up top just with adjusting the afrs. And another reason is because I have to run mid grade in the car (against my will due to detenation). I want to run it off low grade. So Im going to lower the fuel cost and lower the fuel consumption, and have power to boot. I just dont think my current clutch would like the 4800lb dyno roller so I have to wait.

NA in general likes it to be richer when WOT for best power

If you consider 13.0-12.8 afr rich. That is ideal for a n/a car at wot.

 

[4x4le]

Auto fuel table target air fuel rato

5 speed fuel table target afr

Now in 3D
auto first

sorry I got side tracked and it took me this long to actually show you what you were asking.

Im not goign to tonight, but ill have to point out the differences in the decell timing on the auto and 5 speed as well as the min and max injector pulsewidth.

oh, and it appears that the auto ecu would tend to want to run too lean at the max tq rpm and load cells so that wouldnt be the greatest idea. There is actually a different fuel map called thhe gear fuel map that increases the fuel in some areas when your in certain gears with some load but im still not 100% positive how that works out and how you know which map your actually pulling from. What I do know is there is the feature of copying them 2 maps so they are identical which leads to more consistancy.

 

[nissanfreak8]

4x4le, I am just going off what I saw on my friends 5sp sentra when watching the desired idle with a snap-on brick when driving the car, when he would start to slow down it would go to 750 IIRC as the desired idle and the injectors would pulse very little, until he would let the clutch in, then for some reason it would spike the desired idle to 1400.

And when I said the KA likes a rich fuel trim, I meant versus other engines. I don't have experience personally on it, but have talked with a lot of guys that play with all sorts of engines.

Oh and 4x4le, my buddies V6 has a place for an o2 sensor on either manifold, would he need to run a wideband on both or could he get away with capping those openings and putting the o2 sensor before the turbo after the pipe has Y'd together? I don't really know how that would work and am having a hard time finding solid answers. Thanks man.

 

[4x4le]

Your not going to want to put the wideband between the turbo and exhaust manifold as the heat and backpressure is going to make it read wrong and die faster. Now if its going to be a far rear mounted turbo you may have no better choice. There is no real reason to have a wideband in both sides of the engine unless your worried the injectors or intake manifold are poorly balanced, and if that was a worry you would end up with 6 widebands lol (well not lol, some of them multiple wideband setups are sweet!!!)

Just put the sensor down stream from the turbo a good ways so the heat dont kill it.

 

[nissanfreak8]

Ok, will do then, its just kind of odd that mazda have them mounted like 4 inches away from the exhaust mani's. I was thinking of putting before the high-flow cat he wants to put on it, so IIRC it would be about 18 inches away from the turbo. Thanks for the help.

 

[4x4le]

must be before the cat btw. Why put on a cat?

 

[PHeller]

For my purposes, pretty much being all stock, maybe with a header/test/3"back, would the automatic ECU be that much of a disadvantage?

Lets say I were to add an aftermarket manual FPR, could I get better MPG that way?

Either way, I haven't gotten better then 20mpg on 4 tanks, the plugs look great, the wires look in decent condition, and the o2 sensor is hooked up. New air filter, no cracks in the intake, idles fine, runs great...but bad MPG.

I'm not looking for power, but if it comes along with 26MPG I wouldn't complain. Maybe I need to tune.

My interest in the differences between an AUTO and MANUAL ECU are because I've got an Auto ECU on the way, and I'm using it to troubleshoot a few problems. Bad MPG, Speedometer dies randomly, random fuel cut once in a blue moon that isn't related to RPM or GEAR. I want to make sure that the Automatic ECU won't kill my engine.

 

[4x4le]

why are you wanting the auto ecu for? Just for the speed limiter being removed? Do you have a sohc? If so I can make you a bin file without the speed limiter and with a little less of the extra fuel up top where it run insanely rich and you can take the bin file to a electronics repair shop, have them put the bin file on a chip, and install the chip into your ecu. All that should cost around the same as going and buying an auto ecu.

 

[nissanfreak8]

must be before the cat btw. Why put on a cat?

I dunno why he wants a cat, I guess he thinks it will make it quieter, but I just told him to order the long glasspack (like 34") and put it in. And I knew you had to put it before the cat, my truck, my 240, and my lumina were all that way stock.

 

[PHeller]

why are you wanting the auto ecu for? Just for the speed limiter being removed? Do you have a sohc? If so I can make you a bin file without the speed limiter and with a little less of the extra fuel up top where it run insanely rich and you can take the bin file to a electronics repair shop, have them put the bin file on a chip, and install the chip into your ecu. All that should cost around the same as going and buying an auto ecu.

Already got an ECU for $25 shipped.

I'm thinking that my ECU might be the cause of a few problems. If not, it'll be a spare for what your offering.

If you can do what you said for $25, count me in.

 

[4x4le]

I was going to do that for free. You would just have to find a electronics repair shop with the capability of chipping your ecu. Dont tell them its for performance reasons or they will try to charge you out the ass. Just tell them its because the chip needs replaced for some other reason.

 

[nissanfreak8]

Yea, just tell them some moron hooked up your jumper cable wrong and that you just need that chip replaced, or some story that they would believe.

 

[PHeller]

I may still take you up that offer, depending on how the auto ecu works or doesn't work.

Gas is going up again and this 20mpg won't do.

 

[nissanfreak8]

^shush you, I only get 16 mpg in my truck, and I can't even use my 4 wheel drive.