Car sometimes won't start right away for no reason

start
jetta
starters

#1

Hi. I have a 2000 VW Jetta that I got used in 2004 from the dealership. It currently has around 95,000 miles on it and is a standard/manual transmission.



Very rarely, and seemingly so it happens more in the summertime, my car randomly takes a few to five minutes to get started. It can’t be the battery, because it still turns strong, and I’ve been told it’s not the starter (but who knows). The other 98% of the time my car starts without a hitch. When it does happen, it might give me trouble two or three times in a week, then the problem goes away for six months to a year before it happens again. And, also when it happens, after I finally get my car started, the engine revs on its own for about five seconds without me having my foot on the accelerator.



What could cause this completely random occurence a few times a year? Any help would be appreciated.


#2

My guess is the ignition system. Buy one new spark plug. Carry the plug with you and the next time it does not start, get out and pull one plug wire off (pull on the socket part not the wire) put the new plug on that wire and hold the threads of the plug tight against the engine block while you have someone try to start the car. You should see a bright blue spark, and if you are not holding the plug with an insulated tool, you will also see stars! This can rule out a spark problem.

When was the last time you changed the plugs and wires? If you have not done it and you can’t tell when the prior owner last did it, now might be a good time to do it.


#3

When was your last tune-up? Also, a revving engine at idle usually means a vacuum leak. Both can explain your problem. But, intermittent vacuum leaks can be hard to find. And if the check engine light in not on, it is a very small leak that is not enough to put any sensors out of tolerance, yet. I’m not familiar with VW’s, but the trend has been less vacuum line accessories from the designs of the 90’s. It may be a cracked vacuum line or a leaking crack in a vacuum sensor or motor. 8 years is about right for the lines to become suspect.


#4

My friend knows more about Jettas than I do, so I can get him involved and help me out with this scenario. I wouldn’t want to try this myself, as I’m afraid I’d electrocute myself or even worse.

I haven’t had the plugs and wires changed since I’ve been the owner, so it sounds like I need to have those replaced anyway


#5

This also sounds like something to look into. The check engine light is not on, so this could be an alternate explanation as well. Thanks.