VWVortex.com - 1993 Cabriolet (Mk1) 1.8L (Digifant) Sputter, runs rich, poor throttle response after 30-45 minutes
Username or Email Address
Do you already have an account?
Forgot your password?
  • Log in or Sign up

    VWVortex


    Results 1 to 13 of 13

    Thread: 1993 Cabriolet (Mk1) 1.8L (Digifant) Sputter, runs rich, poor throttle response after 30-45 minutes

    1. n00b
      Join Date
      Jun 14th, 2013
      Location
      Columbus, Ohio
      Posts
      8
      Vehicles
      1993 VW Cabriolet Collector's Edition & 2013 Ford Focus ST
      06-24-2013 11:16 PM #1
      All,

      Thanks for taking a minute to read - I have searched, perhaps poorly, and find similar issues, but most of the resolutions have been tried and failed.

      I have a 1993 VW Cabriolet - Mk1 style, NOT Cabrio - with about 97K miles on it. Really good shape overall, and seems like a good first car for my daughter to putter around town in - even though it has that god-awful old 3 speed automatic in it. I had an 80 Rabbit and 80 Scirocco when I was a kid, and they were great back in the day when I had em (mid 80s).

      It has this weird issue whereby it runs fantastically for about 30 minutes at idle, or 45-60 minutes at speed, then starts to sputter, blow smoke and lose all throttle response. Let it sit for a couple of hours, and it will fire right back up and do the whole cycle again. Seems to me like it might be some vacuum leak, but I cannot find it. Below are the many things I have done (or had done by mechanics) to this machine - the bold ones being things I felt pertinent to the issue:

      --Exhaust, manifold through cat
      --new brake booster, water pump, timing belt,
      --new distributor cap
      --new plugs
      --changed oil and filter
      --new air filter

      --new washer pump
      --fixed washer stalk switch
      --new ICM
      --new washer fluid hose
      --fixed wayward headlight
      --replaced radiator fluid resevoir cap (which was missing valve, so coolant would blow out of it as soon as everything got hot )
      --replaced fuel cap
      --fixed various interior bits
      --fixed AC control lever (was out of track) -- still needs recharged
      --replaced AC relay
      --replaced thermostat, gasket and housing
      --replaced blue coolant temperature sensor


      New ICM and timing belt definitely made it run much better (when it does). I am thinking my next step may be the fuel pressure regulator, but was wondering if anyone had the same issue that they eventually found and fixed. I have no whining from the fuel tanks area, and fuel seems to be moving initially fine, so I dont think its the pumps. Thought it was the coolant and overheating, so I replaced the sensor and the thermostat. Doesn't seem like its that now..

      This is definitely something I did not ever deal with on my old VWs, even though much of it is familiar to my days of repairing those critters.

      Thanks much all.

    2. Member tolusina's Avatar
      Join Date
      Oct 18th, 2004
      Location
      313
      Posts
      11,586
      Vehicles
      '95 Ranger, '74 Gitane Pista
      06-25-2013 12:39 AM #2

    3. n00b
      Join Date
      Jun 14th, 2013
      Location
      Columbus, Ohio
      Posts
      8
      Vehicles
      1993 VW Cabriolet Collector's Edition & 2013 Ford Focus ST
      06-25-2013 08:59 AM #3
      Would have never found this as "vanagon syndrome", but it certainly seems similar, and the AFM on these looks to be the same across both the 1.8L in the Cab and the 2.1L in the Vanagon. Thanks for the lead - I'll let you know what ends up happening.

    4. n00b
      Join Date
      Jun 14th, 2013
      Location
      Columbus, Ohio
      Posts
      8
      Vehicles
      1993 VW Cabriolet Collector's Edition & 2013 Ford Focus ST
      06-25-2013 12:49 PM #4
      Well, managed to find the exact 16v capacitor described in the fix (the cable doesn't seem to exist anymore...) and soldered it on as described. Have been running it for pushing an hour now, and it seems to be humming along, whereas before it would die at about 30 minutes. I cleaned up the connectors in the AFM and the cable as well, just to be sure.

      Here in a bit I will take her out for a spin and see what we have - its about 90deg here, so we have heat aplenty.

      I will let you know if that seems like its the permanent fix - I am optimistic though - while I was messing around, I accidentally dropped the capacitor off its weak solder point, and the car immediately started acting up. Re-soldered it, and it fires like a champ.

      Thanks very much Tolusina for the direction!

    5. n00b
      Join Date
      Jun 14th, 2013
      Location
      Columbus, Ohio
      Posts
      8
      Vehicles
      1993 VW Cabriolet Collector's Edition & 2013 Ford Focus ST
      06-25-2013 02:45 PM #5
      Quote Originally Posted by Sucktastico View Post
      Well, managed to find the exact 16v capacitor described in the fix (the cable doesn't seem to exist anymore...) and soldered it on as described. Have been running it for pushing an hour now, and it seems to be humming along, whereas before it would die at about 30 minutes. I cleaned up the connectors in the AFM and the cable as well, just to be sure.

      Here in a bit I will take her out for a spin and see what we have - its about 90deg here, so we have heat aplenty.

      I will let you know if that seems like its the permanent fix - I am optimistic though - while I was messing around, I accidentally dropped the capacitor off its weak solder point, and the car immediately started acting up. Re-soldered it, and it fires like a champ.

      Thanks very much Tolusina for the direction!
      Drove it around for another 90 minutes, no issues. Seems like this was the fix! Thanks again Tolusina! (I wonder if the replacement AFM modules we can buy now have the same issue?)

      How ever did we fix cars before the internet?

    6. Member tolusina's Avatar
      Join Date
      Oct 18th, 2004
      Location
      313
      Posts
      11,586
      Vehicles
      '95 Ranger, '74 Gitane Pista
      06-25-2013 08:22 PM #6
      Quote Originally Posted by Sucktastico View Post
      ....... Thanks again Tolusina! ...
      You are quite welcome, glad it worked for you.
      Frankly I'm somewhat amazed at your quick response and action. Most posters here seem to instantly give up in frustration before doing anything at all with excuses such as "I don't have those tools nor would I know how or figure out how to use them even if I had them in hand."
      Quote Originally Posted by Sucktastico View Post
      ...
      How ever did we fix cars before the internet?
      For me it's always been about information and access to that information, experience over time, often through experimentation including mistakes made to learn what doesn't work, access to information from experienced mentors.
      I've usually found it helpful to learn and understand how things work, especially electrical subjects, learning/knowing how to read AND interpret schematics. Often, gathering complete symptoms, then hitting the schematics will point directly to the components that need meter or bypass testing to confirm good or no good.
      There's another concept that's very effective though there's usually little incentive to practice when all works fine, that is to test good components so that one will recognize bad components when they fail. For an example, click the link in my sig, find the MAF voltage reading thread. I tested a known good MAF so that another forum member could compare on his own car.
      Regarding the "Vanagon Syndrome" I addressed a number of so afflicted Vanagons back in the day, installing the factory harness fix as soon as they were available, prior to that we assembled and installed a voltage regulator system following a factory TSB's instructions, that thing never really worked.
      Vanagons and Cabbys share essentially the same DigiFant system and I'm aware some few Cabbys suffer the same Vanagon Syndrome and cure.
      Experience.
      Quote Originally Posted by kamzcab86
      I hate reading: "But I bought this car for $500 and don't want to put another dime into it."
      ____(hey, it's VW AND it's electrical, what's not to fail?) neoBentley+



    7. Member kamzcab86's Avatar
      Join Date
      Feb 13th, 2002
      Location
      Arizona
      Posts
      17,750
      Vehicles
      1986 Cabriolet Best Seller; 1990 Vanagon Westfalia; 2016 Golf GTI S
      06-25-2013 08:31 PM #7
      Quote Originally Posted by tolusina View Post
      Vanagons and Cabbys share essentially the same DigiFant system and I'm aware some few Cabbys suffer the same Vanagon Syndrome and cure.
      The Vanagons would like this issue be renamed to Digifant Syndrome.







      Will add this to the Digi section on Cabby Info.
      Cabby-Info.com -- Your online guide to VW Cabriolets/Rabbit Convertibles
      Old Blue's Blog -- The adventures of a 1990 Westfalia
      "Fashion is a waste of money that could be better spent on, say, maintaining your car." ~James May

    8. Member tolusina's Avatar
      Join Date
      Oct 18th, 2004
      Location
      313
      Posts
      11,586
      Vehicles
      '95 Ranger, '74 Gitane Pista
      06-25-2013 08:59 PM #8
      Quote Originally Posted by kamzcab86 View Post
      The Vanagons would like this issue be renamed to Digifant Syndrome.







      Will add this to the Digi section on Cabby Info.
      Too late!
      It's already in the vernacular as Vanagon Syndrome and, as shown above, easily googled that way.
      ...edit. Besides, it's somewhat common on Vanagons, fairly obscure one Cabbys. /edit

      Yup, sounds like a good addition to cabby-info, maybe to Old Blue too (if it applies).







      .
      Last edited by tolusina; 06-25-2013 at 09:02 PM.
      Quote Originally Posted by kamzcab86
      I hate reading: "But I bought this car for $500 and don't want to put another dime into it."
      ____(hey, it's VW AND it's electrical, what's not to fail?) neoBentley+



    9. Member kamzcab86's Avatar
      Join Date
      Feb 13th, 2002
      Location
      Arizona
      Posts
      17,750
      Vehicles
      1986 Cabriolet Best Seller; 1990 Vanagon Westfalia; 2016 Golf GTI S
      06-25-2013 09:30 PM #9
      Quote Originally Posted by tolusina View Post
      Besides, it's somewhat common on Vanagons, fairly obscure one Cabbys. /edit

      Yup, sounds like a good addition to cabby-info, maybe to Old Blue too (if it applies).
      Just as obscure on the Golf/Jetta II's too, I presume?

      My van hasn't encountered the problem (yet); there's an entire topic devoted to it on The Samba. But I had to chuckle: Driving back from a van event, my passenger said, "Ooooh, feels like Vanagon Syndrome!" Me: "Um, no; that's what happens when you drive a brick into gusting head-winds."
      Cabby-Info.com -- Your online guide to VW Cabriolets/Rabbit Convertibles
      Old Blue's Blog -- The adventures of a 1990 Westfalia
      "Fashion is a waste of money that could be better spent on, say, maintaining your car." ~James May

    10. n00b
      Join Date
      Jun 14th, 2013
      Location
      Columbus, Ohio
      Posts
      8
      Vehicles
      1993 VW Cabriolet Collector's Edition & 2013 Ford Focus ST
      06-25-2013 10:08 PM #10
      Quote Originally Posted by tolusina View Post
      You are quite welcome, glad it worked for you.
      Frankly I'm somewhat amazed at your quick response and action. Most posters here seem to instantly give up in frustration before doing anything at all with excuses such as "I don't have those tools nor would I know how or figure out how to use them even if I had them in hand."

      For me it's always been about information and access to that information, experience over time, often through experimentation including mistakes made to learn what doesn't work, access to information from experienced mentors.
      I've usually found it helpful to learn and understand how things work, especially electrical subjects, learning/knowing how to read AND interpret schematics. Often, gathering complete symptoms, then hitting the schematics will point directly to the components that need meter or bypass testing to confirm good or no good.
      There's another concept that's very effective though there's usually little incentive to practice when all works fine, that is to test good components so that one will recognize bad components when they fail. For an example, click the link in my sig, find the MAF voltage reading thread. I tested a known good MAF so that another forum member could compare on his own car.
      Regarding the "Vanagon Syndrome" I addressed a number of so afflicted Vanagons back in the day, installing the factory harness fix as soon as they were available, prior to that we assembled and installed a voltage regulator system following a factory TSB's instructions, that thing never really worked.
      Vanagons and Cabbys share essentially the same DigiFant system and I'm aware some few Cabbys suffer the same Vanagon Syndrome and cure.
      Experience.
      Well, this was my last day of vacation, so I still had some time to dedicate to it immediately, and this one had me stumped. I bought this car half for my daughter, half to get back into working on cars (as you pointed out, really haven't had much incentive with newer cars working pretty well, and obscuring all the mechanicals to the point of not being able to even see them when you need to anyways)...and of course half because I have always liked the Cabby and now have an excuse to own one

      Professionally, I troubleshoot large computer systems, and going back to "mechanical" systems didn't have me thinking I would need to look into some of these really old digital hearts on these things. Should have stuck to basic troubleshooting and started at the beginning rather than just hitting potshots like I was. Still don't think I would have ever found it without your direction - the VWs I used to work on couldn't even spell computer, so I wasn't thinking that way.

      Thanks again!

    11. n00b
      Join Date
      Jun 14th, 2013
      Location
      Columbus, Ohio
      Posts
      8
      Vehicles
      1993 VW Cabriolet Collector's Edition & 2013 Ford Focus ST
      06-25-2013 10:11 PM #11
      Quote Originally Posted by tolusina View Post
      Too late!
      It's already in the vernacular as Vanagon Syndrome and, as shown above, easily googled that way.
      ...edit. Besides, it's somewhat common on Vanagons, fairly obscure one Cabbys. /edit

      Yup, sounds like a good addition to cabby-info, maybe to Old Blue too (if it applies).

      .
      Having it out there linked to Cabbys would have probably helped me hit on it sooner, With my luck, of course i would have landed on the one Cabby in Ohio with this issue...

    12. Member CajunSpike's Avatar
      Join Date
      Mar 11th, 2009
      Location
      New Orleans, LA
      Posts
      4,688
      Vehicles
      91 Burgundy Etienne(2), 06 Jetta 2.5, 08 GTI 2.0T FSI
      06-26-2013 10:43 AM #12
      As a possible test of this symptom, would swapping in a different airflow meter assembly(assuming you have one) and running the car to see if the issue is cleared...be a valid test?

    13. n00b
      Join Date
      Jun 14th, 2013
      Location
      Columbus, Ohio
      Posts
      8
      Vehicles
      1993 VW Cabriolet Collector's Edition & 2013 Ford Focus ST
      06-26-2013 06:17 PM #13
      Quote Originally Posted by CajunSpike View Post
      As a possible test of this symptom, would swapping in a different airflow meter assembly(assuming you have one) and running the car to see if the issue is cleared...be a valid test?
      It may, and that was my plan probably for long term - not sure how I feel about having my less-than-stellar soldering job be the key to happy running forever.

    For advertising information click HERE

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •