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Audi 80 2L 8V No spark issue Digifant

30K views 54 replies 4 participants last post by  Stebub 
#1 ·
Hello, for the past 2 weeks or so I've been chasing a dreaded no spark issue with my recently acquired Audi 80 b4 2L 8V ABK with Digifant 1. The car was running fine and etc when i bough it and brought it home and stuff. But 2 days later when I started it up, it started up just fine but then it died in about a min or so, I've tried restarting it but to no avail, so I took off the battery negative or something I did but next day it started up again fine until it died the same way every since then I couldnt start it up no matter what, this was like 2 weeks ago, ever since I've been trying to figure what is up with this thing.

So I tried service manual with the checks on full ignition system etc. but before that I've replaced : Distributor ( the whole thing) , Ignition coil with module ( the newer style 6N0 xxx p/n) , Spark plug wires, and spark plugs.
The distributor is fine and so is the supply and wires to ecu connector which is a Digifant 1 with 38 pin connector not the newer 45 pin one.

On coil connector I get flashes between pin 2 and pin 3 ( + ) as it should be, but I cannot get it to flash between pin 1 ( ground) and pin 2 ( signal) but according to manual it should but ever since then I figured out that the signal /trigger wire is not a 12V but rather a frequency modulated lower voltage like 2V, 2.5V or so running at 30hz when engine is idle ( 800~ rpm) so my 12v Led tester wont flash there, so I connected multimeter to check voltage but it stays on 0 all the time. Also all the wires have proper continuit and supply specially the signal wire. to ECU

It also doesnt flash if i check between terminal 1 and terminal 15 on the coil and it also should. Also I've been trying to manual fire the coil with 12 supply and it works kind of. But still Im trying to figure out what kind of trigger signal is coming in to trigger it with constant 12v to pin3 and constant ground on pin 1 since I cannot manually discharge it like that.

The only thing that should be left is the ECU, but I also opened the ECU and there is no physical damage that I can see unlike other digifants that like to burn up tracks and stuff. So how couldve it gone bad.

I'd much appreciate some help with this issue its driving me crazy.
 
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#37 ·
I would not believe that Bentley is wrong provided I have the service info direct from Erwin.. This car has some other crazy issue... And lets not forget that the car has LPG system installed so who knows what wires are tapped into - I have the wiring diagram and it basically only shows the injectors and coil signal wire- but that does not explain why was the hall sensor output directly hooked to the trigger for the coil and it worked.. And when it died the first thing I replaced was the coil and that was without changing anything around just literally drop in but it didnt fix it. This was back in March 15...then after that came all the other stuff.

Unfortunately I cannot fire the COP coil directly as its resistance is too high vs the ecu input so all the current goes there, and if I increase the resistance toward the ecu it fires the coil fire but then the ecu does not fire the injectors and such because it senses no hall signal input( hall sensor output is 20ma nominal 40ma max not enough for both), so I'm gonna try coming up with a booster circuit so both can work.
 
#38 ·
So update again...


So i managed to get the car to start reliably using my converted coilpack direct from the distributor... but now I am having another ghost issue.

Basically if I remove the battery negative, and put it back and I start the car it runs fine starts with half a key.. if I shut it down and try to start it again it cranks but as soon as it would start I hear a loud bang as you would jam the starter/flywheel with a big steel piece or something, and I stop cause I dont want to break something but it does it everytime. If i remove the voltage again and put it back it starts again fine... I dont understand this bloody car..

Any ideas?
 
#40 · (Edited)
Unfortunately i cannoy look at the engine too, but according to my dad it just stops, but if i keep the key in crank position and it will crank but it will do it every 1 second or so, sometimes i can start it up by keeping it going and maybe touching the throttle. Obviously the spark is not adjusted yet properly but for now I am taking off the starter for a grease job ( been 30 yrs) almost , then we will see.

Starting with "half a key" means that you start the engine effortlessy and nicely , a car does not need much cranking time.
Also i saw your last post today only sorry bout that. :D
 
#41 ·
So update after health issues and stuff... The car is still not running right and right now its non running again. I got it running somewhat using my trigger circuit and newer coil onplug coilpack but the circuit always dies after a while( few days).... I just dont get this POS.

Everything was replaced on this car that could contribute to this issue, I dontget why is there no proper trigger signal preset only the grounding pulse. I got it so i can work on my daily but I couldnt do f*ck all since bloody May( since I bought this thing)... if there is so no solution I am going to have to sell it somehow after spending almost as much the car itself.. I know it was cheap but man it isnt a pleasant experience with the B4 so far.

Please if you have anymore ideas write them.
 
#46 ·
So update on this....


So like a weeks back, I decided to go over everything and again everything checked out except the coil like before.. so I bit the bullet and got a new coil.. Well guess what it worked to my surprise lol

Now I do not actually know if the part was bad from the start or I damaged it when I hooked it up like original coil was done ( and it worked somehow lol??). safe to say I am not buying a magnetti marreli part again( knew they were bad before but it was the cheapest so yeah)

So now I am cleaning the car, doing some stuff on it to get it ready for inspection, pay for insurance so I can have it running on road so I can continue the works on my proper daily project.

HOWEVER, I still have 2 main issues with the car.

1. The oil pressure light is on at cold starts , goes away on hot idle , comes back on any revving.

- First things first, obviously I have checked the oil pressure... Absolutely fine, over 5 bar on cold start, and revving it goes above 6 bar, same thing with hot, 1.5 barish idle , any revi 2.5+ bar. So I obviously replaced the main pressure switch which is know to go bad on these, however the issue is still there, what could be the cause of this.

2. Reversing lights dont work.

- When I bought the car they were working, they stopped working sometime I dont know when. I didnt go to into detail on this yet, could just be a bad bulb ( on both sides? unlikely) or something else. I have noticed though that front or rear fog light bulb backlight indicator ( on the centre console) is on when I turn the lights on even though they arent on, so I wonder if they are on the same circuit or it coulld be reversing switch on the transmission itself, will check this issue too but its not priority atm, just wanted to mention it see what people think.


All in all , still thanks for help or the thought atleast, I am just glad its sorted for now.
 
#47 · (Edited)
New parts are always assumed to be good parts. The biggest fear from mechanics. That is why I've always believed in diagnosis. If the diagnosis is sound, follow it. I went through 4 brand new AMG instrument clusters on a W220 while working at the dealership. I had many engineers thinking I was ruining them or did not diagnose it correctly. In the end, it was Mercedes selling junk. The warranty clerk was not to happy and neither was the claim

Never Eever Worked.

The oil pressure system is simple. One switch works at low RPM, I believe that is grounded if the pressure is too low. The other one is the high RPM switch. I believe that is grounded when the pressure is correct [too low opens the circuit]. Make certain the correct wire is going to the correct switch. Make certain that wire is correctly routed all the way to the cluster. If all the wiring is correct and the proper signals to the cluster, it would be the cluster causing the problem.
 
#48 ·



So I replaced the top one circled which is the main switch, but there is one under the heat exchanger /housing which I cannot identify , I assume its the low pressure switch or oil temperature sender. The issue I cannot find either of these on ETKA ( well I can but it does not seem to be that.)

I have not looked at the cluster wiring yet, but will.
 
#49 ·
So I got it to pass inspection , yay, means I can actually drive it on the roads now, which means I can start tearing the b5 down.

I've noticed though its super slow, guessing 2.slow applies very well or maybe its just the DBC pedal, but still lot slower obviously since I am used to tuned decently fast car, anyway...

I figured out the reversing light issue is actually a cable issue in the trunk, the cable is broken at the hinges obviously, already bought replacement wires to fix that issue. As for the oil pressure light, the red circled one above I noticed that wiring/connection was kinda broken but I dont think it was the issue, however I will crimp new connector and test it, if not that sensor needs to be replaced I guess, however I am still not sure what kind of sensor it is, and what is the part number for it ( for the first time ever lol).


Also looking into changing the oil ,even though it was done recently, what kind should I get, I've seen people recommending 20W50 etc claiming these engies love thick oil , doesnt really get that cold here -15C max, and surerly will go for 50 weight if they like that but maybea 10w50 or something?

Cheers.
 
#51 · (Edited)
Well.... Time for a bump again..

So few months back I got the no spark issue fixed but the car was always a tad too loud, so I couldnt drive it on the road. This week I decided to take it to an exhaust shop to get it fixed, needs new silencer, and final silencer too, and a fix near the cat..

I always noticed the car was very slow IMO ( maybe its just the difference between my tuned car and this) but like something was not right. These days when I drove on overrun/off throttle it was banging like crazy, backfiring constantly like a rally car with ALS, and I ignored it tried not stay off throttle much.
Well anyways, when I went to get the parts for the exhaust , drove like 100m from shop , and I felt the car not going/lost power for like 3 seconds, I tried flooring it and I let off the throttle, oh boi what a choice that was... It backfired massively like an arty cannon, blew up the rear silencer , popped off rear bumper on left side, ofcourse I got pretty scared thought I threw a rod or something but it was so bloody loud. Thankfully it still started but couldnt drive it ofcourse with open exhaust.

So I had to leave the car there( I was planning to anyway since they only fix it up on monday), but there is still some gremlims with this car:
1. It has no lambda sensor atm - would be useless anyway, got a leak right at the flange which is getting fixed, but since there is no lambda, the car runs richer in safe mode ofcourse, but regardless it shouldnt be constantly popping on overrun like a rally car, that is only possible if the car is still injecting fuel when im off throttle which I am not sure why it does- unless the TPS switch is broken and doesnt know its on closed throttle, regardless why did it loose power/cut spark...
2. Instrument cluster does not do anything, but it was working literally 2 days ago, after 1 start it just decided to not work, still got illumination and blinker function on it tho, just no gauges at all. Probably a blown fuse(nr 15 if i remember right) but that does not happen without a short. Another thing like I mentioned before the oil light was still constantly on, which is probably caused by the picture in my last post in this thread above^.
3.When I turn igniton on the wipers do a wipe even when the switch is in normal position, this stopped after the instrument cluster stopped working
4.Hard start when engine hot - takes like 5-10 seconds of cranking to start the car when the engine is hot...

Coupling 2 and 3 together I am still fairly sure there is a short, linking back to original thread ... Also I dont know if it caused the power loss , probably like a spark cut which led to the explosion , since the injectors work regardless if the spark is there on Digifant. There is nothing but issues with this car, all I want it to be is a backup car to drive 6km / day half decently, so I can continue on my B5 (yes still couldnt do anything)
Appreciate any comment, thanks.
 
#52 ·
When you have that many issues, I find that it's best to focus on the problem that you can access the components easiest.

You are correct, spark works all the time, but the fuel should be shut off on decel.

Power starts and ends at the battery. Many people forget the ground side of things. Not a bad idea to perform a voltage drop early on. Building a firm foundation helps with a sound diagnosis. Assuming the ground side is ok, has really screwed a lot of people.

Sorry, not much help.
 
#53 ·
When you have that many issues, I find that it's best to focus on the problem that you can access the components easiest.

You are correct, spark works all the time, but the fuel should be shut off on decel.

Power starts and ends at the battery. Many people forget the ground side of things. Not a bad idea to perform a voltage drop early on. Building a firm foundation helps with a sound diagnosis. Assuming the ground side is ok, has really screwed a lot of people.

Sorry, not much help.

Any comment is appreciated dont worry :)

Another thing I forgot to mention back when I bought the car and scanned it I think it had a throttle position sensor error short to positive or ground cant remember. Anyway I cleaned the connector back when I was searching for the no spark issue.. Now ofcourse if the ECU does not know that the throttle is closed on overrun, it would still be injecting fuel , and it couldve injected so much fuel that the AFR was so rich it couldnt make a combustion leading to the blowup in the exhaust. I dont know for sure if this was the case I am just speculating since I cant even remember before the incident was I on throttle or not.. All I know is I tried pressing it to go, and felt that it didnt react at all, then pressed it even more , still nothing then let off completely and then boom.

Anyway car has been left at the exhaust shop, I'll be picking the parts of silencer up tommorow to recreate the whole exhaust and hopefully I can drive the car home for diagnostics, but I'll try to scan it there tommorow...Wish me luck.
 
#54 ·
So, went to city , got the exhaust all fixed up.. When we started it to look under to check for leaks it stalled in about 2 mins. Restarted backed out, guess what , it died on the road, and couldnt restart it again ( PTSD).

Got the codes scanned.. My suspicions were right. 4 codes ( 1 for the missing O2 sens ignore that):

00523 - Intake air temp sensor -34-10 no elaboration available - short to ground from what I've gathered...
00552 - Potentiometer for Air Flow Meter -34-10 no elaboration available - same thing..
00518 - Throttle Position Sensor -34-10 no elaboration available - again same thing.

So yeah this is probably a short, caused the TPS pos and the maf to drop out, the injectors prolly stayed on a few ms, leading to the explosion in the exhaust, but it seems to affect the spark circuit too because it does not wanna start up(checked tb angle / maf readings with vcds and they were reading okay, bloody intermittent things...), so either dizzy again or ignition transformer.. unfortunately I didnt have my test light or multimete with me. But I just hope they are okay, dont wanna particularly rebuy the same parts again..

As for the instrument cluster, as I thought the fuse is burned( nr12 on my car) and its a 15 amp fuse.. that doesnt break from a small short. This also means that there are multiple shorts/errors because this fuse was broken / open circuit for the ~50km that I've driven before the incident..
 
#55 ·
Hi everyone, I'm having exactly the same problems you Blazius had. 2.0 L Passat 2E engine with 38 pin Digifant, no spark, heard strange loud noises while cranking same as you had. Changed hall sender at the distributor, coil, ECU circuits look ok (not burned), may be also may new coil is not working as it was supposed to.
 
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