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THIS IS A POST OFF OF www.generationdub.com this guy knows his MK2 stuff
THE UBER DIGIFANT thread.
Digifant, AKA digi, digifart, digicrap, came in many flavours in many vehicles in many forms.... we'll start with the "Bosch" generalization, to know the future, you must understand the past.....
As most Bosch systems are referred to as Jetronic, Digifant is know in the Bosch world as an L-Jetronic Variant. Wiki defines them as such
L meaning Luft = german for air, as opposed to CIS systems which were K-jetronic
k meaning konstant (? kontinuous)
Quote:
Originally Posted by wikipedia
L-Jetronic (1974–1989)
Analog fuel injection. This system uses a vane-type Air Flow Meter (AFM). This type of air flow meter is called LMM, LuftMassenMesser, in all Bosch documentation. It had a much simpler and more reliable ECU than D-Jetronic, due to use of custom-designed integrated circuits. It was used heavily in 1980s-era European cars [1]. Similar systems have been built under license by Lucas, Hitachi Automotive Products, and Nippondenso. However, although their key components look similar to L-Jetronic parts, those systems should not be called L-Jetronic and parts are usually not compatible. The 'L' stands for 'Luft', which is a German word meaning air.
LE1-Jetronic, LE2-Jetronic, LE3-Jetronic (1981–1991)
This is a simplified and more modern variant of L-Jetronic. The ECU was much cheaper to produce due to more modern components, and was more standardised than the L-Jetronic ECUs. The connections between AFM and ECU are simplified. Three variants of LE-Jetronic exist: LE1, the initial version. LE2 (1984–), featured cold start functionality integrated in the ECU, which does not require the cold start injector and thermo time switch used by older systems. LE3 (1989–), featuring miniaturised ECU with hybrid technology, integrated into the junction box of the AFM.
LU-Jetronic (1983–1991)
The same as LE2-Jetronic, but with closed-loop lambda control. Initially designed for the US market.
LH Jetronic (1982–1998)
Digital fuel injection, introduced for California bound 1982 Volvo 240 models. The 'LH' stands for Luftmasse-Hitzdraht - the hotwire anemometer technology used to judge air mass into the engine. This air mass meter is called HLM2 (Hitzdraht-LuftMassenmesser 2) by Bosch. The LH-Jetronic was mostly used by Scandinavian car manufacturers and by sports and luxury cars produced in small quantities, such as Porsche 928. The most common variants are LH 2.2, which uses an Intel 8049 (MCS-48) microcontroller and usually a 4 KB program memory, and LH 2.4, which uses a Siemens 80535 microcontroller (a variant of Intel's 8051/MCS-51 architecture) and 16 or 32 KB program memory. LH-Jetronic 2.4 has adaptive lambda control, and support for a variety of advanced features including electronic boost control and fuel enrichment based on exhaust gas temperature (ex. Volvo B204GT engine). Some later (post-1995) versions contain hardware support for advanced diagnostics according to ISO 9141 (a.k.a. OBD-II). The 1995 and newer Volvo 940 vehicles are one such example.
Now, VW has been using L-jet for years, but mk2's and corrados didn't get L-jet until late in the game... Inintally when VW had packaged this injection technoloy as digijet and was using it in the early vanagons (I believe at this point it was still bosch LE#-Jetronic) and it wasn't until about 86-89 that things start to get really ****ed up...
now... after about 86, all watercooled vans (vanagons, transporter, etc) went to the current digifant2 system we know today. Where as the early mk2 jettas made for the california market used digifant1
the digi1 system used on NA jettas for california market were NOT THE SAME UNITS as digi1 used on the G60 supercharged versions.
From what I can tell, Digi1 for G60's wasn't around until about 1989, with the advent of the G60 Corrado, and then was also used in the B3 G60 Passats.
okay.. so now.. from 80-86 we have
digiJET = early watercooled vans
digifant1 CALI = late style efi w/ rudimentary CEL and code storage for mk2 g/j
digifant1 G60 = for forced induction vehicles, Passat / Corrado
and
digifant2 = Normally aspirated system for everywhere else in the world (except cali) used in mk2 g/j and foxes
There were other manufactures that used similar systems, like BMW, ford, etc. (more on this later)
And that's your history lesson for the day.
Most people that I've encountered, usually have digi2 in a mk2 (a2) jetta or golf between 89 and 92. From what I've seen these cars typically have a hell of a time with grounds. The Ecu since it's more of a computerized system is REALLY sensitive to voltage. Various problems can stem from bad grounds from sensors not having the right voltage which gives an improper reading.... from coolant temp sensors to the O2 sensor. Typically now, the other thing with grounds and connections is corrosion. being that digifant is now getting to be about 16 years at it's newest... it may happen to have corrosion on some of the terminals. so let this be a lesson...
CLEAN CONNECTIONS
REMOVE CORROSION
USE DIELECTRIC GREASE OR EQUIVALENT.....
as far as components and sensors go... most, if not ALL digifant systems had the same sorts of sensors and outputs
they are
injectors (all on one injector bus)
ISV (idle stabilizer valve)
Oxygen sensor
throttle switches
knock sensor
Coolant temp sensor
Air flow meter
hall sender *
Ignition control module *
* Debatable; these are separate component systems but required as a whole.
now... for the most part, there's 3 main sensors that you need to be aware of.. and be aware of them in this order.
Coolant temp sensor:
the coolant temp sensor on most of these cars are right in the very front coolant flange, on the top, right in the very front of the head. There's two of them
One is black, the other is blue. The BLACK one goes to the gauge in the dash... you can survive without it. the BLUE one is the one you want to pay attention to. most of the time, these go bad and the car runs riiiiiich, sometimes with a high idle.... (if it runs at all) * in a pinch you can remove the lead from the black temp sensor and plug the blue plug on the black sensor to get you where you need to go.... but replace things and run the car in proper form with the proper parts.
O2 Sensor:
The oxygen sensor on the digi cars are known to do all kinds of weird things... if you've got a cracked manifold, it'll run weird
if you've got bad electrical connections / grounds..... it'll run weird......
if things run great during open loop but **** the bed when is warmed up.... it may be the o2 not providing the right measurements.. or it's dead
The interesting thing about most Bosch systems is that most 3 wire O2 Sensors can be made to work.
If you KNOW you need an oxygen sensor, go to your Friendly Local Auto Parts Store (FLAPS) and ask for an oxygen sensor for a 5.0L ford 302 (came in cougars, mustangs, etc) cut off the shitty ford pigtail and solder that **** onto the proper corresponding VW harness and you're good to go! It costs 3 times less and is ALWAYS in stock.
Air Flow Meter:
to burst people's bubbles... digifant does NOT run a "MAF" it runs an AFM
here's a basic explaination on how it works
Quote:
Originally Posted by qwikxr from the tex
a MAF does read VOLUME of air, or MASS. The BMW, Ford and Digi2 units read FLOW.. Example.. MAF tells the ecu "Hey, Ive got 300cfm of air coming in, you need to fuel for that."
An AFM utilizes a flapper door, that the further the "door" opens, the ouptut voltage increases. This tells the ecu that Im open "this much", so add fuel accordingly.. Since I do not have exact calibration numbers for the Digi2 AFM or the Ford/BMW AFMs handy I'll use this as an example..
Digi2 @ idle, output equals, say, .5vdc..and the Ford/BMW units do, too..
If the Digi unit is capable of a max flow of 200CFM and is open halfway (say, 100cfm) it puts out a voltage of, say, 3vdc, letting the ecu know it needs to fuel for 100cfm..
Now, if the "upgrade" unit is capable of flowing 300CFM, and it, too, is open halfway (150cfm) it puts out a voltage of, say, 3vdc. The ECU sees 3vdc from the meter, and fuels for 100cfm, 50cfm short on fuel for stoich..
and a helpful little video to fix em
A common trick is to find a AFM / VAM from a BMW 5 series and swap it, as it has a larger bore and can flow more air. the caveat is that it needs calibration for it to work properly.. Others claim that because it flows more, that the ECU cannot fuel properly for it without a tune...... others say it works great..... so... yer on your own.. but it's a known modification to the stock vw 1.8L system
late model vanagons and some mk2's had a wiring harness update on the AFM/VAM that corrected an issue with stalling... so if you happen to see that short piece of wire on your intake, that's what it's for.... leave it there.
most of the time these are the sensors to watch out for mostly in that particular order
Links
http://www.loam.org/vw/Vanagon/Vanag...ning/DigiFant/
http://forums.vwvortex.com/zerothread?id=1874220
__________________
![]()
THE UBER DIGIFANT thread.
Digifant, AKA digi, digifart, digicrap, came in many flavours in many vehicles in many forms.... we'll start with the "Bosch" generalization, to know the future, you must understand the past.....
As most Bosch systems are referred to as Jetronic, Digifant is know in the Bosch world as an L-Jetronic Variant. Wiki defines them as such
L meaning Luft = german for air, as opposed to CIS systems which were K-jetronic
k meaning konstant (? kontinuous)
Quote:
Originally Posted by wikipedia
L-Jetronic (1974–1989)
Analog fuel injection. This system uses a vane-type Air Flow Meter (AFM). This type of air flow meter is called LMM, LuftMassenMesser, in all Bosch documentation. It had a much simpler and more reliable ECU than D-Jetronic, due to use of custom-designed integrated circuits. It was used heavily in 1980s-era European cars [1]. Similar systems have been built under license by Lucas, Hitachi Automotive Products, and Nippondenso. However, although their key components look similar to L-Jetronic parts, those systems should not be called L-Jetronic and parts are usually not compatible. The 'L' stands for 'Luft', which is a German word meaning air.
LE1-Jetronic, LE2-Jetronic, LE3-Jetronic (1981–1991)
This is a simplified and more modern variant of L-Jetronic. The ECU was much cheaper to produce due to more modern components, and was more standardised than the L-Jetronic ECUs. The connections between AFM and ECU are simplified. Three variants of LE-Jetronic exist: LE1, the initial version. LE2 (1984–), featured cold start functionality integrated in the ECU, which does not require the cold start injector and thermo time switch used by older systems. LE3 (1989–), featuring miniaturised ECU with hybrid technology, integrated into the junction box of the AFM.
LU-Jetronic (1983–1991)
The same as LE2-Jetronic, but with closed-loop lambda control. Initially designed for the US market.
LH Jetronic (1982–1998)
Digital fuel injection, introduced for California bound 1982 Volvo 240 models. The 'LH' stands for Luftmasse-Hitzdraht - the hotwire anemometer technology used to judge air mass into the engine. This air mass meter is called HLM2 (Hitzdraht-LuftMassenmesser 2) by Bosch. The LH-Jetronic was mostly used by Scandinavian car manufacturers and by sports and luxury cars produced in small quantities, such as Porsche 928. The most common variants are LH 2.2, which uses an Intel 8049 (MCS-48) microcontroller and usually a 4 KB program memory, and LH 2.4, which uses a Siemens 80535 microcontroller (a variant of Intel's 8051/MCS-51 architecture) and 16 or 32 KB program memory. LH-Jetronic 2.4 has adaptive lambda control, and support for a variety of advanced features including electronic boost control and fuel enrichment based on exhaust gas temperature (ex. Volvo B204GT engine). Some later (post-1995) versions contain hardware support for advanced diagnostics according to ISO 9141 (a.k.a. OBD-II). The 1995 and newer Volvo 940 vehicles are one such example.
Now, VW has been using L-jet for years, but mk2's and corrados didn't get L-jet until late in the game... Inintally when VW had packaged this injection technoloy as digijet and was using it in the early vanagons (I believe at this point it was still bosch LE#-Jetronic) and it wasn't until about 86-89 that things start to get really ****ed up...
now... after about 86, all watercooled vans (vanagons, transporter, etc) went to the current digifant2 system we know today. Where as the early mk2 jettas made for the california market used digifant1
the digi1 system used on NA jettas for california market were NOT THE SAME UNITS as digi1 used on the G60 supercharged versions.
From what I can tell, Digi1 for G60's wasn't around until about 1989, with the advent of the G60 Corrado, and then was also used in the B3 G60 Passats.
okay.. so now.. from 80-86 we have
digiJET = early watercooled vans
digifant1 CALI = late style efi w/ rudimentary CEL and code storage for mk2 g/j
digifant1 G60 = for forced induction vehicles, Passat / Corrado
and
digifant2 = Normally aspirated system for everywhere else in the world (except cali) used in mk2 g/j and foxes
There were other manufactures that used similar systems, like BMW, ford, etc. (more on this later)
And that's your history lesson for the day.
Most people that I've encountered, usually have digi2 in a mk2 (a2) jetta or golf between 89 and 92. From what I've seen these cars typically have a hell of a time with grounds. The Ecu since it's more of a computerized system is REALLY sensitive to voltage. Various problems can stem from bad grounds from sensors not having the right voltage which gives an improper reading.... from coolant temp sensors to the O2 sensor. Typically now, the other thing with grounds and connections is corrosion. being that digifant is now getting to be about 16 years at it's newest... it may happen to have corrosion on some of the terminals. so let this be a lesson...
CLEAN CONNECTIONS
REMOVE CORROSION
USE DIELECTRIC GREASE OR EQUIVALENT.....
as far as components and sensors go... most, if not ALL digifant systems had the same sorts of sensors and outputs
they are
injectors (all on one injector bus)
ISV (idle stabilizer valve)
Oxygen sensor
throttle switches
knock sensor
Coolant temp sensor
Air flow meter
hall sender *
Ignition control module *
* Debatable; these are separate component systems but required as a whole.
now... for the most part, there's 3 main sensors that you need to be aware of.. and be aware of them in this order.
Coolant temp sensor:
the coolant temp sensor on most of these cars are right in the very front coolant flange, on the top, right in the very front of the head. There's two of them
One is black, the other is blue. The BLACK one goes to the gauge in the dash... you can survive without it. the BLUE one is the one you want to pay attention to. most of the time, these go bad and the car runs riiiiiich, sometimes with a high idle.... (if it runs at all) * in a pinch you can remove the lead from the black temp sensor and plug the blue plug on the black sensor to get you where you need to go.... but replace things and run the car in proper form with the proper parts.
O2 Sensor:
The oxygen sensor on the digi cars are known to do all kinds of weird things... if you've got a cracked manifold, it'll run weird
if you've got bad electrical connections / grounds..... it'll run weird......
if things run great during open loop but **** the bed when is warmed up.... it may be the o2 not providing the right measurements.. or it's dead
The interesting thing about most Bosch systems is that most 3 wire O2 Sensors can be made to work.
If you KNOW you need an oxygen sensor, go to your Friendly Local Auto Parts Store (FLAPS) and ask for an oxygen sensor for a 5.0L ford 302 (came in cougars, mustangs, etc) cut off the shitty ford pigtail and solder that **** onto the proper corresponding VW harness and you're good to go! It costs 3 times less and is ALWAYS in stock.
Air Flow Meter:
to burst people's bubbles... digifant does NOT run a "MAF" it runs an AFM
here's a basic explaination on how it works
Quote:
Originally Posted by qwikxr from the tex
a MAF does read VOLUME of air, or MASS. The BMW, Ford and Digi2 units read FLOW.. Example.. MAF tells the ecu "Hey, Ive got 300cfm of air coming in, you need to fuel for that."
An AFM utilizes a flapper door, that the further the "door" opens, the ouptut voltage increases. This tells the ecu that Im open "this much", so add fuel accordingly.. Since I do not have exact calibration numbers for the Digi2 AFM or the Ford/BMW AFMs handy I'll use this as an example..
Digi2 @ idle, output equals, say, .5vdc..and the Ford/BMW units do, too..
If the Digi unit is capable of a max flow of 200CFM and is open halfway (say, 100cfm) it puts out a voltage of, say, 3vdc, letting the ecu know it needs to fuel for 100cfm..
Now, if the "upgrade" unit is capable of flowing 300CFM, and it, too, is open halfway (150cfm) it puts out a voltage of, say, 3vdc. The ECU sees 3vdc from the meter, and fuels for 100cfm, 50cfm short on fuel for stoich..
and a helpful little video to fix em
A common trick is to find a AFM / VAM from a BMW 5 series and swap it, as it has a larger bore and can flow more air. the caveat is that it needs calibration for it to work properly.. Others claim that because it flows more, that the ECU cannot fuel properly for it without a tune...... others say it works great..... so... yer on your own.. but it's a known modification to the stock vw 1.8L system
late model vanagons and some mk2's had a wiring harness update on the AFM/VAM that corrected an issue with stalling... so if you happen to see that short piece of wire on your intake, that's what it's for.... leave it there.
most of the time these are the sensors to watch out for mostly in that particular order
Links
http://www.loam.org/vw/Vanagon/Vanag...ning/DigiFant/
http://forums.vwvortex.com/zerothread?id=1874220
__________________
