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OK I got One?

My 91 cabby 1.8 L. when I first start it , it keeps dieing. but after about 1 min. it smouthes out and runs fairly well.

When I hold the gas down lets say to 1500 rpms I can see the tach is moving up and down maybe 50 rpms. but still running real deasent. when its idling at about 600 rpm on the tach it stays steady. anyone got a cure?

Thanks ahead of time Bat-Man

Reply to
Bat- Man
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Not totally sure about Cabbys but I think by '91 they used the Digifant injection system.

If that's true, then the standard Digifant idle checks are warranted:

  1. ensure ISV is working.

  1. If working, remove it and clean it with carb/FI cleaner, reinstall.

  2. check vacuum lines for leaks

  1. check coolant temperature sensor for ECU (although this is a cheap replacement part too...many folks just replace it)

  2. check 02 sensor

  1. Check MAF or the idle/full throttle switches (depending on what you have...some digifants had a MAF and some had the switches).

  2. Reset the ECU (if possible...the procedure varies depending on the Digifant system)
Reply to
Matt B.

You wrote

  1. ensure ISV is working.
  2. If working, remove it and clean it with carb/FI cleaner, reinstall.

mabye Im dense Matt but what is a ISV?

I checked the cooling temp sensor last nite by unpluging it and startijng the car, it started and ran pretty good without dieing, after about 2 min. I plugged it back in and it ran fair then to , so Im off to get one at Advance in a little bit. I live here in Illinois across from St. Louis and everyone swears by advance.

Ive only got a book that covers rabbit, golf and jetta, 75 to 92 and I couldnt find anything clost to the ISV.

Ive got a 90 to 93 Cabroilet service manual ordered from jcw that will be in in about 5 days then mabye I can fig some things out

Thanks Matt I'll get back to tell you if that cooling temp sensor worked.

I think your right that it has the Digifant ll fuel system in it.TTYL

Bat-Man

Reply to
Bat- Man

ISV = idle stabilizer valve.

Atop the valve cover look for a metal canister lying on its side with hoses going from/to it and it will also have an electrical connector. it might be secured with a big rubbery bracket too.

With the ignition on, you should be able to hear and feel a very faint humming coming from it if it's working. Don't have the engine on because it'll drown out the humming...just turn the key to the "on" position and the ISV should faintly hum/vibrate.

If it's working, remove it and spray some carb/FI cleaner into every available orifice and clean it out good. Reinstall.

OK although the dealer charges no more than $15 for this item too. make sure you get a new o-ring too. Replace it when the car is stone-cold so you don't get coolant spraying everywhere. Even then it'll probably dribble out a little bit when cold.

Yeah late A1 Cabriolets have Digifant but I just wasn't sure starting which year.

Reply to
Matt B.

Thanks Matt I cleaned that ISV and got a new coolant temp sensor and that fixed it, It starts and runns like a top Thanks a lot for your help Matt TTYL Bat-Man

Reply to
Bat- Man

glad it worked out. both should have been easy and cheap fixed too huh?

those things are among the most common/standard problems when it comes to Digifant idling and running issues.

Reply to
Matt B.

Yeh, youve been a big help on my problems, Matt are you a vw mechanic you sure know a lot about water cools, all my knowledge is in the air cools.

One more Q, does that digafant ll have a pvc valve? I looked in the book but couldnt determine where or what it is.

Is it the big round thing connected to the air intake and the valve cover, plastic and about 3 in. in diameter?

TTYL Bat-Man

Reply to
Bat- Man

sure know a lot about water cools, all my knowledge is in the air cools.

Thanks for the compliment, but I'm not a mechanic. I'm just a Digifant owner and hate to take the car to the dealer when I don't have to.

BTW...there's a good Digifant-for-dummies sort of page at

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that covers most basicDigifant info and understanding. FWIW, lots of people like to diss Digifant (mostly because there isn't a heck of a lot of aftermarket tuning options for it I think) but in stock form it's been a fairly reliable system for me. In the 175K miles I've had my car, I've only had to replace the coolant temperature sensor ($14 and this is a part shared with other non-Digifant VWs of the 1980s and 1990s anyway), the fuel pressure regulator ($75), and occasionally reset the Digifant unit (possible with Digifant I, not sure about Digifant II).

but couldnt determine where or what it is.

I believe it does.

plastic and about 3 in. in diameter?

Yes I think that's it.

Reply to
Matt B.

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