ALFAGTV6.COM

Hi

I'm having a tune up (ECU re-programming) done on my GTV6 3L. on a rolling-road-bench in a couple of weeks.

I'm currently running on stock Bosch Jetronic ECU (0 280 001 134) and it has a seperate black ignition box besides it.

When I'm having the ECU re-prog. I wan't the rev-limiter moved up a bit higher as it kicks in already @ 5688 rpm (right where the engine starts to sound really good ) but the mechanic said that there is a slight chance that the thingy that controls the rev-limiter is located inside this black ignition-box, and NOT in the actual ECU..? Therefore he cannot promise me that he is able to move the rev-limiter and if THAT'S the case I'm seriously considering a totally different injection-system... (But what? Megasquirt..?)

The engine is equipped with Shankle headers, C&B cams and heads has been ported, so I wanna get "as much" power out of the engine as possible from this setup, and DEFINATELY wan't the rev-limiter moved to @ least 6500 rpm. (But how "much" is recomendable? I don't wanna push things to far... )

I'm also modifying the air flow with a AFM from a BMW 535i... We managed to adjust the BMW-AFM and make the engine run with it, but it clearly lacks fuel during driving. Hopefully a re-prog. of the ECU will fix that...

Maybe I should mention that the car runs with a Lambda but has no cat.

Can anybody guide me a little?

I've been reading quite a lot on this site but my knowledge isn't either good enough or I just miss some major points because of language-differences So please forgive me if this topic have been up before... I tried my best before posting...

All help is appreciated - thanx in advance

Can nobody really help??

Thought this was the mother of GTV6 forums

It's kinda hard to tell what you're really asking but I see a problem right at the start. Reprogramming an L-Jet ECU will be quite difficult because it does not have a chip, it's analog.

Mats wrote:It's kinda hard to tell what you're really asking but I see a problem right at the start. Reprogramming an L-Jet ECU will be quite difficult because it does not have a chip, it's analog.

Yup,resistor packs..

I think the jetronic has a fuel cutoff. I can't remember if the spark box also has a spark cutoff.

Greg Gordon is selling a modified Jetronic box, for about $99 I think. Raises the fuel cutoff limit.

"Reprogramming an L-Jet ECU will be quite difficult because it does not have a chip, it's analog."

Thanx guys! That was REALLY helpful I knew the guru's were hiding somewhere in here

Yesterday I actually picked up a whole stack of 75/Milano 3.0 America parts and between it all there actually was a Motronic box

Do you have any idea if it's an "easy" operation to get my 3.0 engine running on that - or do I have to change the ignition-rotor too?

Or do I just forget the above and use Megasquirt instead?
If so, do you then suggest getting rid of the whole AFM and use a MAF-sensor?

'easy' is relative...depends on your electrical/mechanical skills

Alfas are easy to work on electrically and mechanically if you have a good basic background in electrics and mechanics...(they are a nice blend of electrical and fluid/air/vacuum and mechanical things from the 80's)...

If you want, you can even "reprogramme" the jetronic boxes by messing with resitor slopes...but that is probably the most difficult thing to do on the original car from a mental standpoint.

Consider the Alfa as a 3 year old or a spicy girlfriend, good days and "other" days, but the experience you will love overall.....

......

Well, is the Motronic from a V6? do you have the pulleys with the motoronic toothed ring? Pickup and so on and so forth. Then you need someone that can actually hack into the Motronic to remap it.
Megasquirt is probably a lot easier, loads of info right here on the site.

Mats wrote:Well, is the Motronic from a V6? do you have the pulleys with the motoronic toothed ring? Pickup and so on and so forth. Then you need someone that can actually hack into the Motronic to remap it.
Megasquirt is probably a lot easier, loads of info right here on the site.

Yes, it's from a V6 - but I guess Megasquirt is the real deal.

Thanx for all the info though

Hello,
About the rev limiter on a 75 L jetronic:
- the rev limiter is in the Ignition control unit
- there is no rev limiter in the L Jet Control Unit.

There is three type of Ignition control unit:
0 227 921 035 - Serie 1, rev limit 5900
0 227 921 035 - Serie 2, rev limit 6200
0 227 921 035 - catalyser, rev limit 6500
the ignition advance curve is similar for both in normal or cruise. 2° mor for cata at WOT, the idle curve have small differences but compatible. There is 6 curve : idle, idle cold, normal, normal cold, WOT, WOT cold.
in the serie 1 and 2, 5 different curve.

For the ignition control unit, i have the solution, two way:
- change the Eprom inside ( the original is soldered but no problem)
- change the box, use an original serie 2 or for catalysed.

i can provide
- a copy of the Bosch original serie2 or for catalysed car.
- a serie 1 modify Eprom with rev limiter at 6200, 6400, 6500.

I prefere the Serie1 modify Eprom for the Idle cold regulation and with 5° advance.

Warning, the serie1 and 2 have the same part number, for Eprom and box!
It is necessary to use a test bench ( Y have one with logic analyser and analog scope)

If you need some more info about this black box, i have.

About the L Jetronic, it is possible to modify. I depend of the needs. discusion in an other Post.

Best regards

Hi Nimbus

Thx for the very helpful info.

I think I'll try to find this one first and see how it works:

"0 227 921 035 - catalyser, rev limit 6500"

(Cheapest solution )

And if I'm not satisfied I'll go for the MegaSquirt in the end. Seems almost as much trouble to modify the Jetronic as building a new MS.

There is 2 rev limits if my memery is still good
The lower one is in the ECU.
The one in the spark box is a lot higher.
The map for a L-jet in in the AFM so now you have a BMW MAP.
There is a bunch of resistors cut with a laser. as the flap move it selects one of the resistors. That resistoer is programed for that amount of air flow. The ECU takes that and the temp of the air and the temp if the coolent as well as the local APSI and mixes it with amps doing analogue math. Then it takes that to make PWM using the pulse comming off the dizzy. There is is a revlimit that will cut the fuel you can just change the resistor for that or cut it out.
You do not want the spark rev limit to come on. It will back fire and blow up the cat.
The fule cut revlimit is the only safe way to limit with a cat.

As FI goes the L-jet is not very good. any aftermarkit computer controled system is light years better. Now if you have a motrinc with the trigger wheel it is not so bad.
I would say add the trigger wheel if you do not have one and put programable FI on.
I put a VEMS on mine and it works very well. getting rid of all the sparkscatter due to the dizzy is a big difference by its self. The motor runs so much better. The spark scatter causes a lot of motor shake. I can fell the difference in the shifter and lack of rattel.
I used the newer VAG COPS and they fit perfect in the 12V head I did not run a cam sync so I run semi-seq and fire 2 coils at the same time (wasted spark mode)

I know in 3.0 ECU box there is definately a rev limiter because I have one ECU no rev limiter and one w/rev limiter...one w/rev limniter kicks in about 6200rpm....

I put the 'fixed' ECU in...rev as far as I want..

changed resistor in 'fixed'box

Hmm... I'm honestly a bit confused now

Don't get me wrong - I really do appreciate everybody's input on this subject but I don't know what to believe (or do) right now... hmm...

BTW, the number on my Ignition box says: 0 227 921 036

Cboxoak: see

http://home.swipnet.se/joakim_adolfson/ ... -text.html

http://www.firstfives.org/faq/ljet/jetronic.pdf

http://www.205gti.com/bosch/index.htm


Also: i use a 3.0 ECU..one with no rev limiter and one with rev limiter