# My engine dies when I take my oil cap off



## Dubluva (Sep 16, 2002)

I'm trying to get my 1988 Jetta Digi2 back on the road. Car was idling yesterday and when I removed the oil cap the car shut off. Isn't that a sign of a bad PCV system? What else could cause that? The car has no exhaust system after the cat yet but that shouldn't cause this. 
Also the car will idle fine for about 5-10 minutes and then the idle will get really rough as if the car has a _severe_ misfire, almost shutting off. I think it may be a fuel issue, but what are the symptoms of incorrect fuel flow, or volume? I have another pump I can put in, but don't want to throw parts at it. Also my fuel pressure gauge uses a schrader fitting and won't work on the digi fuel rail.
Any Ideas?


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## WaterWheels (Aug 14, 2005)

Dubluva said:


> Car was idling yesterday and when I removed the oil cap the car shut off. Isn't that a sign of a bad PCV system? . . . Also the car will idle fine for about 5-10 minutes and then the idle will get really rough as if the car has a _severe_ misfire, almost shutting off. I think it may be a fuel issue, but what are the symptoms of incorrect fuel flow, or volume? Also my fuel pressure gauge uses a schrader fitting and won't work on the digi fuel rail.


Strange as this may sound, that is what the engine should do if the system is sealed up like it should be. VW, at least not with your engine, did not use PCV valves, but it is a closed system so what happens is correct. Yes it could be a fuel pressure issue or an ignition issue, to hard to say from here and what you said. Schrader valve on the fuel pressure gauge? One of mine does have one on the gauge itself to release pressure as it holds the highest reading until released, but not on the "input" end of the hose/gauge. In any case it would be far cheaper to just pick up a cheap gauge to check the fuel pressure then replace a pump which could be fine.


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## Dubluva (Sep 16, 2002)

Thanks for the reply. I had the car running today and the idle was loping/sputtering again, I noticed that when the car sputters it puts out black exhaust as if its running rich, so I pulled out the fuel pump and the filter. I don't think I've ever seen a pickup screen that dirty before it was so dirty it looked like there was mud on the screen. I replaced it with another pump and a clean screen, but I can't start it till I get another filter.
I'll post my results.
Any other input?


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## ziddey (Apr 16, 2006)

it sounds like your oxygen sensor is shorting out. digifant can trim absurdly rich. i had that problem when I was trying to get a 20 year old o2 sensor off and failed the first time. the snow belt will do that to it..

At the time, I didn't have a long wrench, so I borrowed one of those stupid o2 sensor sockets. Busted up the wiring, and it must have shorted internally. Had to drive with the o2 sensor unplugged until I could get it removed.

also, I believe a lot of gm cars had a schrader valve on the fuel rail for testing back in the day.


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