# what makes digifant so bad??



## Str8pipingti (Oct 10, 2010)

the only reason i can find is that digifant is not suitable for turbo. but for an NA setup i see no issues. anybody else have there reason for not liking digifant??
FI is FI in my opinion


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## WaterWheels (Aug 14, 2005)

No, fuel injection is not fuel injection. There are different types and different abilities of fuel injection which date back many years. But I have to say I am glad you posted this question as I really would like to hear the answers/responses. I seriously doubt many can explain just what they believe makes one or the other system good or bad. I believe they just think from hearing others say things or from their own dealings with a poorly set-up or maintained or tuned system that it is no good. I guess we will now see.


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## sarcastro (Jun 3, 2010)

I have heard that Digi I from any G60 motor is good, throttle tip in and off idle response is good, and the trims are very tunable (forced induction is a hallmark of the g60 motor)

Digi-II has the inverse of all the above, (throttle response fuel trimming issues, and not particularly tunable) as I understand it (working on an install of a Digi II motor now) 

I have seen all manner of mods with CIS-e and most regard it as a worthwhile system

dont know much about motronic

megasquirt is kind of like being handed a loaded weapon.. you could feed your family with it, or blow your darn leg off...


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## mkdons (Dec 14, 2010)

The biggest complaint I've heard from folks who maintain my 8v is that Digifant FI can be a pain to tune because of its electronic-pulse nature and the associated parts that go with it. Not bring all that well-versed in fuel management, I can't say for sure why people cringe when the word Digifant is uttered. I'd like to see where this thread goes-it may answer some more questions...


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## Seax_Smith (Jun 1, 2007)

Presume you are asking about Digi II, the most common form mark II's, on every 8-vavle from mid 87 to 92 or somewhere around there.

Considering L-Jet and it's variants have their origins in the late 70's, there really isn't anything "wrong" With Digi II. Are there things which could be better? Most certainly. Were the tech advances avalible through the 80's and early 90's to imprve digi II? Pretty much. Was it cost effective for anyone to try considering Digi II and OBD don't really get along all that well? No.

A properly tuned digi system will do today, what it was designed to do a couple of decades ago. So long as the components are in good working order and there are no ground nor vacuum leaks, it will run fine. 

If set up properly and maintained properly, it is rather predictable and will run well until component failure, vac leak or ground issue make it run poorly.

Form what I have seen, most people complianing about digi, don't seem to understand it all that well, nor have they taken the time to learn about it. It is pretty much it's own little, unique creature in the FI world. Digi II plays by its own set of rules.

Good points: Parts are easy to find and not all that expensive. Will run well if set up well and maintain, and is rather trouble free until component failure, vac leak or ground issue happen. It is pretty simple to deal with ounce you learn what the components are and what they do and why they do it. Maintains a decent balanace between MPG's, power and emissons output.

Bad pionts: Ground and vac senstive. Some replacement components are not the best quality. There is boat load of bad info on the web about digi II. Can't run a turbo on it. Has a very aggresive ingnition map which leads to a dead spot in the throttle off the line, which is easily fixable with chip of choice. Digi II doesn't have the tweakability of any of the CIS variants.

There are some things which can be done to help digi II, like upgrading to a 4 wire O2 sensor, having a good exhaust behind it, etc ...

But for the most part, Digi II therfore Digi II, and you need to play by its rules. If you do, your car will run fine on it. 

Is it reasonable to compare it to a modern FI system? No, old school tech is not cutting edge tech.

Is it reasonable to compare it to old school tech which has recieved a bunch of little improvements over the decades, like CIS Motronic, not really.

If you are willing to learn Digi II's rules and paly by those rules, Digi II is rather bullet proof, reliable and predictable as well. Is a very good choice for an 8-valve daily driver so long as you don't go overboard with the engine mods. Digi Doesn't seem to mind P&P, over sized valves, 270 cam, 1.8 0r 2.0 makes nor real difference, doesn't mind 10:1 compression.

Digi II's biggest fault is being 30 year old tech which cant live up to the expectations of people who don't understand it and expect digi II to be something it is not.

Personally, it is not my favorite system at all, but it is also the system I put on my ABA half swap which went into my daily driver, which is a littl other than stock.

SHORT VERSION:
what makes digifant so bad??

Ignorance and unreasonable expectations.


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## ziddey (Apr 16, 2006)

The problem most people have with Digifant is with idle control I'm imagining. It's why you see so many people wanting to delete ISV's.


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## Seax_Smith (Jun 1, 2007)

ziddey said:


> The problem most people have with Digifant is with idle control I'm imagining. It's why you see so many people wanting to delete ISV's.


Funny th8ing about ISV delete to control Volitile Idle Syndrom is that high idle is mostly caused by vac leaks or the throttle switches, less so by a dirty or broken ISV, sometime by a dirty AFM.

High Idle = bad maintainence.


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## ziddey (Apr 16, 2006)

Oh indeed, a problem is a problem. The difference is Digifant tries to compensate somehow, vs other systems, you're left with however the mixture is brought back to stoich if possible, and that's that. So then it's easy for people to just adjust the idle screw or whatever to compensate, and not really notice the penalty in throttle response, as the mix will rely on the oxygen sensor to be pulled back to stoich.

But then with Digifant, you'd easily see an idle that hunts or otherwise does strange things.

Then again, the only Digi2 car I've owned so far has been a Fox2, which uses the traditional idle boost valves like the older cis variants, and has no knock sensing abilities, so it purely goes by the map. No qualms with it, except an AFM that would do funny things when it got real cold out and I was hundreds of miles from home.


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## Str8pipingti (Oct 10, 2010)

well from my stand point. i think i want to see a turbo on a digi car. and it is possible. just need to do some real research. if there is a will there is a way!


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## Seax_Smith (Jun 1, 2007)

Digi I maybe, Digi 1 Cali dont know.... Basic 8-valve Digi II, probably with a couple extra ciricuts added to the board with a new sensor or two added on the other side, little voodoo, a black box and a few blood scarifices, maybe....


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## Svedka (Jul 4, 2008)

Digi 2 sucks there is now correct way to remap the timing or change the required fueling also you are sucking all your air in from a 2in squared box (i should go measure because it is probably smaller). 

Sure you can throw a turbo at it but no it will never run correctly and you would have wasted your time and money. 


Digi 2 lasted for 3-4 years it is completely outdated and no one continues to try and improve on it. 

DIGI stands for digital fuel injection it was made to run off of low octane fuel and comply to standard emissions testing not to make performance or power. 

AEM or whatever the company was were the only ones to completely remap the digi ecu's and even then people seen very little power gains for the cost and they stopped production a long time ago. 

Countless people have beat this topic to death and there is a reason you never see any completed digi2 FI projects, either the builder came to his/her senses or they melted some pistons and wasted a turbo. 

read these are just a few from the last few months. 
http://forums.vwvortex.com/showthre...etup-but-what-chip-do-i-get-for-digi2-1.8-16v 
http://forums.vwvortex.com/showthread.php?4706763-cis-e-to-digi2 
http://forums.vwvortex.com/showthread.php?5119726-1.8-8v-turbo 
http://forums.vwvortex.com/showthre...hip-a-digi-1-(cali)-ecu-ecu-037-906-023-b-KEN


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## Seax_Smith (Jun 1, 2007)

Digi isn't actually bad in and of itself. It willl still do today in a 92 VW what it was dowing in porches, bmw's and medcedes back in the 80's. I work and will provide adiquit enginmanagement to a 1,6 - 2.0 lither 4 cykinder engine. 

Is it the best option for power? NO!. Is it the best option for MPGs? NO! Is it the best option for eliminating bad emisssions? NO!. Is it pretty amazing considering the tech level it came out of? YES!


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## Str8pipingti (Oct 10, 2010)

yea well the conclusion was that i need to got to motronic and call it a day! bump some digi!


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## Gin (Feb 19, 2004)

I agree with Seax_Smith. DIGI is a bullet proof system. However, diagnostically it's horrible.

There is zero scan tool support. No codes for reference, no vag-com nonsense, and not even a check engine light. So what this translates into is a major pain for your local mechanic or guy behind the counter at the parts store. So in order to properly diagnose a problem, you absolutely need a bently manual and knowledge of using a multimeter.

Other issues, the ECU does not have the ability to omit the 02 sensor, which is troublesome if it shorts out. Throttle switches are a pain do to there location. It is obviously not suitable for boost. 

Given the popularity of engine swaps and turbo applications, it only exaggerates the above and adds to the "bad rap".


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## 16V VW (Aug 1, 2004)

im sure you can run 4psi on stock digi2. there is not reason you can't 4psi is a little extra air and shouldn't make it wonky. the only bad thing is the intake mani sits right ontop of the exhaust.

crossflow head and light boost!

i love my digi2 counterflow. slow as crap, reliableish, but somehow it's a spirited driver with the 268 cam


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## TheBurninator (Jan 7, 2009)

Svedka said:


> Digi 2 sucks there is now correct way to remap the timing or change the required fueling also you are sucking all your air in from a 2in squared box (i should go measure because it is probably smaller).


I am pretty sure it is closer to 1.5x1.5 inch opening. Geee that isn't a restriction at all :banghead:



Svedka said:


> Sure you can throw a turbo at it but no it will never run correctly and you would have wasted your time and money.


Absolutely correct. Even a digi 1 setup would be much better suited to this. Let alone motronic (not cis motronic).

With how the MAF works on these cars they are maxed out on the reading at full throttle in stock form. Whatever would make someone think this would work well with even more flow isn't thinking at all.



Svedka said:


> Digi 2 lasted for 3-4 years it is completely outdated and no one continues to try and improve on it.
> 
> AEM or whatever the company was were the only ones to completely remap the digi ecu's and even then people seen very little power gains for the cost and they stopped production a long time ago.


No one wants to try and improve on it because they know it is a fruitless thing to do.

IIRC it was AMS in california that created the only digi 2 chip that had a different timing map. They got a very very small gain out of it.



16V VW said:


> im sure you can run 4psi on stock digi2. there is not reason you can't 4psi is a little extra air and shouldn't make it wonky. the only bad thing is the intake mani sits right ontop of the exhaust.
> 
> crossflow head and light boost!
> 
> i love my digi2 counterflow. slow as crap, reliableish, but somehow it's a spirited driver with the 268 cam


I am sure I have a turbo sitting at my house that at 4psi would be more than digi2 could come close to handle. I hate that people use the psi moniker for flow output. 

Also I don't see why people constantly use a crossflow head as another moniker for power. Hell the OBDII crossflow head ports are attrocious. OBDI ports are decent but a counterflow head with the same valves will flow just as well if not better. 


My input on digi2: It is semi reliable. No where near CIS. No where close to tunable. It is a stock system that works in a stock configuration and does not respond to modifications well. Motronic is a much better modern system and is easy to trouble shoot, diagnose, and fix. It also responds better to modifications. But if you want to make power you don't use a stock management system at all.


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## Glegor (Mar 31, 2008)

TheBurninator said:


> I am pretty sure it is closer to 1.5x1.5 inch opening. Geee that isn't a restriction at all :banghead:
> 
> 
> 
> ...


good post man, i enjoyed reading it! i like how you worded alot of it..

and pointing out that a counterflow head is not as bad as people think. i bet they flow better than an OBD2 head..


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## TheBurninator (Jan 7, 2009)

Glegor said:


> good post man, i enjoyed reading it! i like how you worded alot of it..
> 
> and pointing out that a counterflow head is not as bad as people think. i bet they flow better than an OBD2 head..


Thank you :thumbup:

I will see if I can find a pic of the OBD2 head. The valve guide bosses make that head junk for making power. And the exhaust port on the crossflow head in general has a really harsh turn before the valve. Worse than the counterflow.


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## Prof315 (Jan 5, 2009)

When Digifant came out in 89-90 it wasn't really any worse than anything available and better than a lot of other systems. The problem with it now is that it is a 20 some year old engine management that hasn't been built new for nearly 20 years. The wiring harnesses are all old and brittle, as mentioned QUALITY replacement parts are harder and harder to find and the ECU processor speeds are stupid slow by today's standards.

With an absolute ton of affordable standalone systems on the market it just seems stupid to me to use old outdated junk when you can do better for less money.


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## Glegor (Mar 31, 2008)

sure its like comparing apples and oranges, but has anyone ever looked at the fuel system on toyota pickups of that era?

they have all the same sensors, and work just like a digifant 2 system, but they are a HELL OF ALOT MORE RELIABLE then a digi setup..

not kidding, toyota and VW injection are almost identical in terms of function, and the parts they take to operate. but the toyota system is extremely reliable. every fuel injected toyota ive owned has been super reliable, fuel system wise..

they are still not tuneable, but work good. no good to build power with tho.

and the turbo toyotas back then must have had something like digifant1..


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## TheBurninator (Jan 7, 2009)

Glegor said:


> and the turbo toyotas back then must have had something like digifant1..


 I have a few friends with 22RET trucks.

They still use the MAF sensor like any other toyota at that time. Keep in mind they are all denso sensors and not bosch, that could have something to do with it.

The turbos are low boost. IIRC 6lbs and you can't do more than 10 without issues. And the turbo is small. Especially for such a large 4 cylinder engine.

As you said, not tunable at all. They leave alot to be desired.


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## Glegor (Mar 31, 2008)

so, the fact that they are denso is basically the only thing you can come up with making the toyota injection more reliable?

because thats the exact same conclusion that i came up with. better components, and wiring..

i really know nothing about turbo trucks tho. i know a supra CT26 is a great upgrade. along with some other MAF sensor..


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## TheBurninator (Jan 7, 2009)

Glegor said:


> so, the fact that they are denso is basically the only thing you can come up with making the toyota injection more reliable?
> 
> because thats the exact same conclusion that i came up with. better components, and wiring..
> 
> i really know nothing about turbo trucks tho. i know a supra CT26 is a great upgrade. along with some other MAF sensor..


Yep, only thing I could come up with. The wiring gets just as brittle as VW wiring. Also the way the ECU sets priority for some of the sensors and the safe mode it has could attribute to this also.

Correct. And even the CT26 is a small turbo. :screwy:
One of my buddies tried the supra MAF but found it ran very poorly. Switched back to the stock MAF and all was better.


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## Glegor (Mar 31, 2008)

TheBurninator said:


> Yep, only thing I could come up with. The wiring gets just as brittle as VW wiring. Also the way the ECU sets priority for some of the sensors and the safe mode it has could attribute to this also.
> 
> Correct. And even the CT26 is a small turbo. :screwy:
> One of my buddies tried the supra MAF but found it ran very poorly. Switched back to the stock MAF and all was better.


i believe that the camry/cressida MAF is a direct swap.

you just have to get the maf with the right resistance/spring rate as the stock unit. im sure it was just like putting a V6 maf on a 22r.. they run like crap. but they RIP on the top end. it ran like complete crap everywhere but completely wound to the moon.. and it ran real good up there. more power for sure, but it wasnt driveable. idk why it ran better on the top end either. the door in a V6 maf is the same as a 22r maf.

but i think that the original ECU is setup so that it wont take much more flow from the MAF than what you get factory.


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## JoggerNot (Nov 6, 2009)

the wiring and the non-tune-ability sorta blows...


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## Glegor (Mar 31, 2008)

JoggerNot said:


> the wiring and the non-tune-ability sorta blows...


glad you got too see this thread Steve, i was going to point it out, but it slipped my mind


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## PDXGTI8V 2.0 (Oct 12, 2005)

After living with my Digi2 system now for 20 years and 236,000 miles, i have to say it has been incredibly bulletproof...I am still running the from the factory ECU and injectors. I have replaced the MAF once with a used unit from a lower mileage car due to wear on the original unit. Ive replaced the CTS 3 times in 236000 miles. Still on the original fuel pump, though I have replaced the intank pump once. 

As stated, the system gets a bad rap from idiots who dont know how to work on it and dont own a Bentley manual... 

Performance tuning ability? If I wanted true performance, Id sell my GTI and buy an older BMW.....


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## PDXGTI8V 2.0 (Oct 12, 2005)

Gin said:


> I agree with Seax_Smith. DIGI is a bullet proof system. However, diagnostically it's horrible.
> 
> There is zero scan tool support. No codes for reference, no vag-com nonsense, and not even a check engine light. So what this translates into is a major pain for your local mechanic or guy behind the counter at the parts store. So in order to properly diagnose a problem, you absolutely need a bently manual and knowledge of using a multimeter.
> 
> ...


 Oh no!! you have to diagnose the problem with knowledge and common sense, instead of having a damn computer tell you whats wrong with the car, OH NO!!! the sky is falling! 

lol!!:laugh:


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## Glegor (Mar 31, 2008)

its nice to have the computer tell you whats wrong, but what happened to the days when you could give a mechanic a car, and he would diagnose and fix it without even needing a computer? 

you can check every sensor on an electronic car with a multi-meter.. 

theres your On Board Diagnostics right there.. keep a friggen multimeter in your glove box.. lol.. 

digifant isnt really a bad system, but compared to a toyota injection system of similar functions and age, they suck.. 

the injection system used on toyota pickups, as far as i can tell, is basically a copy of Digifant, built by denso. 

they NEVER have problems like the digi cars do.


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## TheBurninator (Jan 7, 2009)

Glegor said:


> its nice to have the computer tell you whats wrong, but what happened to the days when you could give a mechanic a car, and he would diagnose and fix it without even needing a computer?
> 
> you can check every sensor on an electronic car with a multi-meter..
> 
> ...


 Even with cars with OBD functionlity a multimeter goes a long way with diagnosing issues.

I think some of the short comings of digifant is use of throttle switches instead of a TPS. I have had horrible luck with the throttle switches failing on my digi cars.


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## PDXGTI8V 2.0 (Oct 12, 2005)

TheBurninator said:


> Even with cars with OBD functionlity a multimeter goes a long way with diagnosing issues.
> 
> I think some of the short comings of digifant is use of throttle switches instead of a TPS. I have had horrible luck with the throttle switches failing on my digi cars.


 still on my original, from the factory, set of of throttle switches...and they've never been adjusted, and they work perfectly....dont see how they can wear out or get out of adjustment, unless of course they are f*cked with unnecessarily by previous owners...


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## TheBurninator (Jan 7, 2009)

PDXGTI8V 2.0 said:


> still on my original, from the factory, set of of throttle switches...and they've never been adjusted, and they work perfectly....dont see how they can wear out or get out of adjustment, unless of course they are f*cked with unnecessarily by previous owners...


 On my 3rd set now in 4 years. Roll pin keeps dropping out of the lever on the full throttle switch.


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## sarcastro (Jun 3, 2010)

its all those full throttle launches  


on a serious note, the pendulum swung back the other direction, got everything installed half in half out of the car, couldnt get it to run.. at all... 

went to the junkyard and I found a 1.6 cis manifold, will this bolt up to a 1.8? my eyes think it will but well would be nice to know from someone who knows, and before any haters say "search" i did. I came up with squat! 

also can I use the DigiII TB on the 1.6 manifold?


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## Guidofester (Aug 28, 2003)

*manifold*

Yes the MKI manifold will work for your application. One issue you are going to have though is installing the throttle switches. I know you can use parts from the MKI throttle body to make the MKII throttle body work. I've never done it but I know it's been done for ever. Back in the day Neuspeed sold a MKII throttle body modifyed to fit the MKI because it was a little bigger.


I love my digi cars. Great commuters. Yes I know they have limitations when it comes to modifications and making horsepower,But when tuned, and maintained properly, they perform as they were built to perform. Mine has provided me with years and years of some what reliable service. 

The other thing that I love about digi is that it's already electronic fuel injection. More efficient than CIS. I"ve never lost a main fuel pump in a digi car. Not like every CIS car that I've ever owned. How many damn pumps did I have to replace in MKI's? All of them.

Plus it's a little easier to convert it to another engine management system such as Megasquirt, where it is already electronic. The digi system may not be the best system, but it definitely isn't the worst. I vote the 1.8 16v CIS-e to be the worst system.

I'm hoping to install a 16v into my digi autocross car this spring. Really looking forward to running the 16V on digi. I'd like to try Megasquirt in the future, but that bumps me into a different class so I'll stick with the digi for at least this year.


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## TheBurninator (Jan 7, 2009)

sarcastro said:


> its all those full throttle launches
> 
> 
> on a serious note, the pendulum swung back the other direction, got everything installed half in half out of the car, couldnt get it to run.. at all...
> ...


Car doesn't ever get launched... Just seems to be the nature of the beast... Oh well. Swapping to something MUCH more reliable here shortly.

The 1.6 Mani will bolt up to the head but the throttle body opening will be smaller than a late CIS/digi2 throttle body so you will need to open it up

I would just find a VW fox/G60/Late Cabby manifold.


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