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[bobbber]

I keep reading articles about the LE3 Jetronic system - as used on my 33. Pretty much ALWAYS it says that the Jetronic system is outdated and inefficient - for example mine generates 107BHP as opposed to the carbed version at 118BHP.

So - what are the shortcomings of the Jetronic system - and can they be overcome?

Basically - what's wrong with it!!!!!!!

Thanks!

Bob
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Fiat Bravo 165 Sport

[tvatavuk]

I think Ecology had been primary problem that cut of some horses compared to Carbed version.
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Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo

[gritsop]

Hi,

I agree with Tino; emissions were the primary concern of antipollution laws. There is always a trade off in real world; either we have performance or we have healthier people, and of course legislation has chosen the second.

I had such talk with my mechanic some time ago and the only thing he replied was that his blood test had revealed high concentrates of lead in his blood vessels ... so there was not real need to continue the talk...

Now regarding the Jetronic isuue. It was the first electronic management system after K jetronic which was a mechanical fuel injection system. In addition L-Jet complied to the strictest antipollution laws of US and California. One can say that it used to be efficient back in the 80's; nowdays modern EFI systems are superior compared to L-Jet ... but it is almost 25 years after

Regards,
_________________
Thanassis Gritsopoulos
1991 Alfa 33 1.4 IE
2001 Alfa 147 1.6 Distinctive

http://www.alfa-restoration.co.uk
Parts Shop: www.alfa-restoration.co.uk/shop

[bobbber]

Ok... I understand that stuff (and thanks for the replies! )... but surely the LE3 can therefore be 'tuned' to 'do away' with the environment and perform like a MoTronic system then?

Or is there something 'hardcoded' into the system which fixes it to a lean mixture? (This I understand can be sorted by making the ECU think the engine coolant is cooler than it actually is!?).

So.... other than a predetermined lean mixture (for the environment), the additional restriction of the 'flap type' AFM, and the timing issues associated with the car not having a TDC sensor, what is the actual difference that makes the Jetronic system PANTS?

Bob
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Fiat Bravo 165 Sport

[bobbber]

Anyone?
_________________
Fiat Bravo 165 Sport

[gritsop]

Hi Bob,

Actually the predetermined values given to the ECU by various sensors are hardcoded in the Jetronic chip which has "mapped" every combination of engine load and sensor values.

Another way to boost the L-Jet 33 is to replace the chip; a fully programmable one giving low end torque increase plus the emissions issue.

In addition, the fact that L-Jet of Alfa 33 does not have a TDC sensor, is that a distributor exists. The ignition advance value is not contained in the ECU and because of that the distributor is set up at 8 degrees fixed.

If we wanted the car to have a TDC sensor then we should get rid of the distributor and hardcode the ignition advance values into the L-Jet circuits. Note here that the vacuum advance values (the small barrel in the distributor) must also be stored in the ECU as it can reach up to 15 degrees!. To cut a long way short the function of the distributor is substituted by the TDC sensor which reads the timing marks and sends this data to the ECU for proper processing and precise ignition.

It is a totally different approach of engine management system.

Just my 2 cents.
_________________
Thanassis Gritsopoulos
1991 Alfa 33 1.4 IE
2001 Alfa 147 1.6 Distinctive

http://www.alfa-restoration.co.uk
Parts Shop: www.alfa-restoration.co.uk/shop