fooling the stock ecu

[Guest Anonymous]

couldnt the stock ecu be fooled..by adding/subtracting resistance to the circuits feeding it from the afm/o2sensor

(below the rpm the turbo kicks in)to lean out oversized injectors....?.....s

[SleeperZ]

It is possible to fool an analog ECU like the early Zs '75-'78 to make minor compensatory changes, but you will not get satisfactory results trying that with a digital ECU like the ZX and the ZXT. The O2 sensor is used to make minor mixture changes during cruising conditions only - the O2 sensor and feedback loop is very slow. The injector size is internally mapped, so any sensor fooling only works within a small range, maybe 10%. For idle and full throttle, the ECU is going off a map, and there is only a couple things you can do.

 

1. Reprogram the chip. This is the best way, and makes the ECU very happy.

 

2. Add unmetered air in proportion to the increase in injector size (ie: add 40% more air if you run 370cc injectors on a turbo), bypassing the AFM. This will probably help the idle mixture a little bit, but perhaps not at all. But it gives an added bonus of less intake restriction, and will give proper fuel mixtures under cruising and full throttle. The only drawback is you may have to pull spark advance, because the ECU is basically being fooling into operating at a lower part on it's ignition curve, and a turbo ECU without a boost sensor will pull timing toward the top of it's fuel map.

[awd92gsx]

Hmm...

 

Are there any modifications that can be made to the MAF's on the Z to lean it out some?

[Guest super280z]

Bill,

 

sorry man, im not too keen on working with the stock datsun injection. it's a serious Pain IMO. most serious guys just switch over to an SDS setup. i'd like to talk dsm stuff with you sometime if you have time. i'll send you an e-mail. you can reach me at my post name@hotmail.com

[Guest Anonymous]

I have a device on my desk here called an EFIE. It is intended to offset the voltage coming off of an o2 sensor by a configurable amount. You can find info on these at the manufacturer's web site.

Go to:

http://www.eagle-research.com/products/pfuels.html

and scroll down to:

Electronic Fuel Injection Enhancer

or

EFIE Device

 

There are also manuals for building several fuel saving devices. There will soon be a manual for DIY water injection too!

[Guest Anonymous]

If you want to know some basics about the AFM, shoot me an e-mail. Did you know with one minor mod, I can make ANY Z-car pass the emissions portion of smog (w/ or w/o a cat). Not that I cheat the system....ok I do a little.

 

For some reason it really pi$$e$ the smog tech guys off when I adjust the A/F mixture right infront of thier shop. Go figure...

 

Nic

[awd92gsx]

I'm trying to figure out how to install an Apexi Super AFC into a Z. I know somewhere somebody told me they did it, but I haven't been able to figure out the dip switch settings yet (although, I haven't really tried installing it yet, either).

 

Running an AFC would greatly enhance the stock injection system. I've seen DSM's with stock computers and AFC's run 10's.

 

Basically, an AFC (Air Fuel Converter) allows you to modify the MAF...err..AFM signal to either add or remove fuel at different RPM points. Very handy if you have upgraded to a larger injector or just want to tune the stock fuel curve to a more power friendly setup.

 

If I can figure it out, I'll be sure to let everybody know.

 

Usually adjusting O2 voltages does not change anything because during WOT most ECU systems stop paying attention to the O2 sensor and rely on preprogrammed fuel maps instead.

[Len]

Bill

Have you tried contacting the Company that built the device? You might obtain some good information.

Len

[awd92gsx]

Len,

 

Unfortunately, they're not much help. I've visited the site and they pretty much tell you if you can't find it, don't email them about it because they don't know.

 

I'll get it figured out. I need to start with finding some 280Z EFI schematics and checking voltages and then cross referencing them with some other possible settings...

[Len]

[Guest Anonymous]

.....isnt he.....dead?

.....s

[Len]

If your talking about Mr. Lee; Yes but his soul, philosopy and legacy lives on.........

[Guest Anonymous]

Hey, those AFC units really work (if you can figure it out). My friend bought one for his 95' 240SX and he said his stock system only ran with 50% air. Now with the Apexi unit he can run 75%+ effecincy with the tap of a button. Pretty cool.

 

I want to buy one. When I get money (which is what everyone says).

 

Nic

[Cruez]

Dunno if this helps, but when I bored my L28 .020 over and put flat-tops in it, It did not like the factory EFI settings.

 

To correct the problem I opened up the AFM (not just the adjustment screw) and did some adjustments there. Worked great.

 

Now on the turbo l28 its gonna be trickier, as Sleeperz stated, because the computer will try to compensate for the changes you make...theoretically..