[Diy_efi] Air/Fuel meter now working! And L-jetronic

[Astrona]

> Here's the dyno results. Notice that the fuel mixture stays constant until
> I hit 4600 rpms then it starts to gradually lean out. I've heard this is
> where the AFM maxxes out at. It looks to me like this is more RPM related
> than boost related.
I've played with AFM and measured pulsewidth of le-jet.

On my 1.8E Opel 115hp NA stock engine
It increased PW proportionally up to max torque point (4800).
After that, when torque was slowly falling, the PW fell too but a bit
slower - so mixture richened.
That was the case up to max HP-point (5800). After that PW started to fall
faster.
When plotted on graph i saw that duty cycle % remained the SAME from 5800 to
7000, although torque fell pretty fast.
So, LE-Jetronic kind of flooded it - it's for safety i guess.

I noticed that on every test the PW-curve had same shape, but with different
offset!  Pulsewidth-peaks were on different RPMs,  +/- 200RPM.
The offset shows, that ECU trys to follow the VE-curve (TQ) by measuring
load not RPM. It wasn't "closed-loop" pw calculation from load, since i had
replaced stock camshaft with racing one(316deg), but still had the PW-peaks
in the stock cam positions.
http://www.hot.ee/slyy/auto/18E_k6ver.jpg

I don't know if it is cut into AFM resistors or soldered in with ECU's
"bias-resistors".
My ecus from 1983 & 1986 showed same results with the same AFM, but they
were made for same engine model (although ecus were different inside).
http://www.hot.ee/slyy/auto/kadett_b/ecu/
For example by richening through loosening the afm-spring, will have
sideeffect of moving these "hard-coded" peaks to lower rpm, and "flat" "VE
map" ecu would be better :).
These peaks are upto 15% of total PW.

I'm not giving my head for it, i tested it a year ago.

Cheers!

----- Original Message ----- 
From: "James Seabolt" <turbofiat at hotpop.com>
To: <diy_efi at diy-efi.org>
Sent: Friday, June 17, 2005 2:05 PM
Subject: Re: [Diy_efi] Air/Fuel meter now working! And L-jetronic


At 03:46 PM 6/16/05, you wrote:
>--- James Seabolt <turbofiat at hotpop.com> wrote:
>
> > I built a custom turbo system about 8 years ago for
> > my Fiat Spider and it uses L-jet. It works great for
> > 7# systems.
>
>You used the flapper-type VAF?


Yes.

>How did you determine
>plenum air pressure?

Not sure what your talking about.


>How much boost did you run?

I run just 7 pounds and about 5? retard. Will sort of. You'll have to read
my whole page about how I have my boost retard system setup.

Here's the dyno results. Notice that the fuel mixture stays constant until
I hit 4600 rpms then it starts to gradually lean out. I've heard this is
where the AFM maxxes out at. It looks to me like this is more RPM related
than boost related.

http://users.chartertn.net/jseabolt/2nddyno.jpg

http://users.chartertn.net/jseabolt/80spider.htm


>You've piqued my curiosity.  I'm only familiar with
>one L-Jet style application on an OE turbo vehicle,
>and that was very low-boost, and retarded ignition
>timing as boost built.


7# of boost gives this little car quite a kick. I put a 4.11:1 final drive
it in so that helps it even more. But not for acceleration. Before putting
the turbo on the pinion gear broke in the original 3:90 final drive. I had
this spare axle laying around and stuck it in.

The drivetrain is all stock in this car. So far I haven't busted anything.
It's real hard to find stronger components for these old Fiats these days.
There is no way I could push 14# of boost in this car and not break
something.






James Seabolt
Tennessee, United States
Homepage --->>> http://users.chartertn.net/jseabolt/

2003 Subaru Baja
1980 FIAT 2000 "turbo" Spider
1968 Ford Fairlane 500 (Not a Ford Galaxie!!)
1987 Yugo GV 1500cc also turbocharged









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