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    Thread: Audi 80 2L 8V No spark issue Digifant

    1. 06-28-2020 10:10 AM #26
      I'm trying to get a recently purchased Vanagon ready to go on a vacation for a client. They're leaving in a few days. So I have not had time to check my wife's car.

      You are performing a test against the positive but that does not mean much since you do not have a reference to what it's suppose to be. So is it a good test or not. Right now, it's worthless information.

      The test Bentley [again, I absolutely hate to be wrong and I rarely assume since it just leads down the wrong path] says is to use the ground pin. The test is measuring the power signal and you are not getting one. Sounds like that is the issue. Your test is showing it's getting a ground signal but the computer does not care, it needs a power signal. Does the connector need to be plugged in? Your car is old, but with the newest cars, most test must be hooked up or the computer may remove power/ground because it 'sees' it unplugged. If Bentley says to have it unplugged, maybe it's true but I would perform the test plugged and plugged in.

      I'll do my best to make those tests today, but I do not want to look at this young family and say you're not going on vacation. I certainly do not want to get a call saying the Vanagon died too because of my hastiness.

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    3. 06-28-2020 10:38 AM #27
      Quote Originally Posted by Butcher View Post
      I'm trying to get a recently purchased Vanagon ready to go on a vacation for a client. They're leaving in a few days. So I have not had time to check my wife's car.

      You are performing a test against the positive but that does not mean much since you do not have a reference to what it's suppose to be. So is it a good test or not. Right now, it's worthless information.

      The test Bentley [again, I absolutely hate to be wrong and I rarely assume since it just leads down the wrong path] says is to use the ground pin. The test is measuring the power signal and you are not getting one. Sounds like that is the issue. Your test is showing it's getting a ground signal but the computer does not care, it needs a power signal. Does the connector need to be plugged in? Your car is old, but with the newest cars, most test must be hooked up or the computer may remove power/ground because it 'sees' it unplugged. If Bentley says to have it unplugged, maybe it's true but I would perform the test plugged and plugged in.

      I'll do my best to make those tests today, but I do not want to look at this young family and say you're not going on vacation. I certainly do not want to get a call saying the Vanagon died too because of my hastiness.

      Bentley says to perform test with connectot unplugged so its perfectly fine to have it floating and yes ofcourse you would think thats the issue. But then it says to replace ecu if wiring is good, which it is ,checked continuity etc all according to bentley procedures , and also replaced ecu (and the ecu was pulled from a working car, so i can deffo confirm that). And yes ofcourse real life tskes priority, i would not expect it otherwise.

    4. 07-05-2020 02:01 PM #28
      So update again..


      I got the car to fire the plugs and start somehow using a newer style COP coilpack, I made a circuit that converts the ground pulse from the ecu trigger to a 12v positive as thats what this smart coil works with and yes it fires, I made a long threaded screw with SAE connector at the end so I can connect it to the distributor and car starts roughly, and when it does there are misfires and eventually dies, trying adjusting distributor etc but does not really help ( even though its bang on anyway), but I'll try sorting it out maybe change back to old plugs because they have less sparkgap and who knows how strong these coils are vs the stock coilpack.

      If I wont get it running soon I might have to scrap the car, its been 2 months really, I cannot continue with my main build cause of this things and its very very annoying.


      Anything new on your side Butcher?

    5. 07-11-2020 09:44 AM #29
      I will be working on my wife's Cabriolet Sunday to replace the valve guide seals. I will perform so tests and give you the results on a good running engine.

      Stay tuned.

    6. 07-12-2020 05:31 AM #30
      Aight cheers, but is that car a californian car? Else you will have the sepearate ignition module and stuff, only cali digifant is similar :/.


      EDIT: Oh yeah, forgot to say , I knew some people reported their issues got fixed by replacing / resoldering their nr 30 relay ( power supply). Initially I didnt take the relay apart because like I said it passed all bentley tests including the connector too. Well 2 days ago I took it apart and sure enough there were 3 dry joints, which I resoldered( I resoldered all of them anyway) they are nice and shiny now, also purchased a new ignition switch - sometimes the starter would disengage while starting or engage while just switching ignition on ( but not starting) for half a second or so, hopefully this fixes that issue.. if not I really think something is shorted and somehow its turning the starter on for a sec without switch being turned to start lol. Havent had time to check yet.
      Last edited by Blazius; 07-12-2020 at 08:44 AM.

    7. 07-12-2020 08:41 PM #31
      It's a Digifant I car, yes, California.

      The coil has three wires. Power, ground, and signal. The power and ground is 12v. The signal wire is green/black and is located in the middle. It has a 1.6V reading when the engine is running [at idle] and a .02v when the engine is off [key on].


      The distributor has 3 wires also. Power, ground, and signal. The signal wire is Green/White and is located in the middle. The power is also 12v. The signal wire is 7.3v while running [at idle] and 11v with the key on, engine off.


      I did not move the distributor to see if the signal changed when the trigger lined up. I suspect it would since it's a hall effect sensor.

      I suspect that the square wave that comes from the distributor goes to the EFI ecu. That information gets changed and modified. That signal is then sent to the ignition coil. That signal is normally grounded and the ground is removed when the spark needs to occur. The EFI controls the ignition timing as well as the fuel injection.

      This what I was trying to say but I'm certainly not the best at explaining myself. I hope this additional information helps. Again, both the distributor and the coil have 12v. I did not bother hooking up my scope to insure the signal was indeed a square wave. In my book, it just makes sense that it is.

      When I was in Reno with no spark, a quick test showed I had a signal out of the distributor and one going to the coil. The only thing left was the ignition amplifier that attaches to the coil. The ignition amp changes that EFI signal for something the coil can use. Now you can buy a coil with the amp built in. I was able to buy the amp and got home. I put a good coil/amp unit in because the new one I purchased would cause the tach to jump when the ignition key was turned on. It was a matter of time before that would fail.

    8. 07-12-2020 09:03 PM #32
      Yep.

      My coil has 12 and ground, hall sensor has ground and 12v , and signal goes out to ECU(confirmed), it is like you say, gets modified based on coolant temp and dwell time and stuff and gets sent to the coil.
      Now like I said and showed and your test now confirms , there should be a positive peak on the signal square wave, that is missing on mine, only the 0v ( ground) is present. So I am unsure why the ECU does not send the positive voltage down the wire, the only explanation I think of is that the wire is grounded somehow , but it shows no continuity to either positive or ground. the ECU is confirmed to be good, taken from a running car.

      I will see if there a positive voltage on the signal again after I fixed up the ecu supply relay and cut off the broken connector( a while ago) tommorow, since I didnt get a chance today because I was charging the battery.
      I assume you tested the signal positive vs the battery negative directly or did you test on engine(itself) earth ?

    9. Yesterday 11:51 AM #33
      Quote Originally Posted by Blazius View Post
      So I am unsure why the ECU does not send the positive voltage down the wire, the only explanation I think of is that the wire is grounded somehow?
      So what makes you think that the ECU puts power on the line? I would think that there is a slight bias voltage on that line and the ECU pulls it to ground. I'm certain you will agree, it's got to be one or the other but it's possible your thought is wrong. Yes, I know I could be wrong too. If there is a bias voltage, I would suspect the ICU in the coil.

      On the bright side, I replaced my wife's valve guide seals [which I did 2 years ago] because of a misfire and blue smoke on cold start ups. It's fixed, she just drove out and no blue cloud.

    10. Yesterday 01:30 PM #34
      Quote Originally Posted by Butcher View Post
      So what makes you think that the ECU puts power on the line? I would think that there is a slight bias voltage on that line and the ECU pulls it to ground. I'm certain you will agree, it's got to be one or the other but it's possible your thought is wrong. Yes, I know I could be wrong too. If there is a bias voltage, I would suspect the ICU in the coil.

      On the bright side, I replaced my wife's valve guide seals [which I did 2 years ago] because of a misfire and blue smoke on cold start ups. It's fixed, she just drove out and no blue cloud.
      The reason I think that is because Bentley says so and it very clearly fails that test( with the wires "floating" as in coil completely unplugged). The LED would only light up if its get positive from signal wire and the waveform info from Autodata and Vivid confirms it too.
      Still didnt have the chance to test since the improvements I made and its half 9 PM again Gotta replace sparksplugs in main build, but hopefully I can do it or maybe tonight really fast, we'll see.

    11. Today 05:51 AM #35
      Well just tested it again, there 0 volts on that line all the time( like before the wire if basically floating then ecu grounds it with no positive peak). Even if I can get it started with my contraption it will stop running after 2-3 seconds or so , and when it does I can hear the fuel pump prime noise( I can also hear it clearly during the motor is running the loud prime sound, which isnt the usual run sound of the fuel pump, I think) constantly going. Whatever I do I cannot it get to run reliably, and its very very very annoying , it has been 2 months now.. Without the MAF it starts a bit easier but it does the same thing.

      I have confirmed that the ECU pulses the injectors , does not keep them flooded ( usual digifant issue).

      Just for **** and giggles I am going to put my og coil back and see if I get a spark now ( very unlikely but I'll do it anyway thats how frustated I am).

      Yup , no spark with either OG coil or new coil on factory like setup I love doing the same stuff expecting a different outcome
      Last edited by Blazius; Today at 06:41 AM.

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