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Mon Dec 20, 2004 12:16 pm

this started happening three months ago. it never really bothered me but i would like to know what the problem might be. i start up the car to let it warm up and it starts at normal idle for maybe about two minutes. then it will start idling really high. i usually warm up my car for 5 to 10 minutes. when i get in the car i tap the gas pedal really lightly and it goes back to normal idle. this never happened before it actually started when i took it to get painted. it always idled real nice. could it be the accel.cable?does it need to be greased maybe?carb? what do you think.

Mon Dec 20, 2004 12:42 pm

It sounds like the electronic choke is getting a tad stuck. Don't know how much you know so here is the full spill;

When the engine is cold it needs a ritcher gas/air mixture in order to run well. Once the engine warms up, the mixture can be leaner. This is accomplished via the electronic choke; a plate that 'chokes' the air going into the carburetor while at the same time it keeps the accelerator arm more open than usual. The electronic part is a heating element. When it heats, the choke opens up allowing full air flow.

Look at your carburetor when cold. The iddle adjustment screw rests on a series of steps. When the car is cold it rests on the top step. As it warms up, the choke opens, and it steps down until it rests on the lower one. Often the engine vibrations are enough for it to click down by itself. When that doesn't happen, you have to tap the gas pedal.

If this anoys you, the cure is to take the carburetor apart, clean, lube, and adjust.

Mon Dec 20, 2004 1:13 pm

sounds good. thanks

Mon Dec 20, 2004 1:17 pm

And, by all means, STOP letting your car warm up.
Twist the key and go!

Mon Dec 20, 2004 1:31 pm

"Twist the key and go" is one of the worst bits of advice I have ever heard. Have you any idea of how much damage you do ?
I'm not saying let it warm up untiul the choke comes off but it you are starting a car that has sat for more than 6 hours you need at minumum about 30 seconds at idle to get proper oil coverage to where it is needed.

What is happening with your idle going so high is two fold. #1 you need to make sure the choke closes when you depress the accelerator on a cold engine. It sounds like it is. then you have to make sure it is opening fully within a few minutes of you starting the car. Sounds like that is happening too or the car would chug and cough and foul spark plugs.

What IS happening is the fast idle adjustment screw isn't slipping down the fast idle cam (that step looking thing attached to the left side of the choke shaft). As the choke opens, the fast idle cam moves and the fast idle screw should "walk" down the cam. You should clean the cam and the tip of the screw and polish both. Also, this is usually a sign that the throttle return spring is too strong.

This is a pretty normal occurance, but you shouldn't really let the car idle that long on it's own. If you are trying to warm up the heater or defroster, make sure the thermostat is in place and adjusted properly and try driving the first few blocks in a lower gear.

Mon Dec 20, 2004 3:11 pm

my car drives really smooth after warmed up.usually wont drive it if warmed up less than five minutes. i never turn the key and go, it just doesnt drive the same. however i will check these possibilities and share the results

Mon Dec 20, 2004 5:42 pm

OK, so don't take my word for it, I've only been driving Volkswagens since 1968 and repairing/restoring them since a short time after.
Look in any owners manual that was delivered with a new air cooled Volkswagen. One of the tips for operation is to avoid warming up the car before driving off.
Choke return spring???
Would you care to enlighten us by describing exactly where this choke return spring is located?
The only spring is housed in the automatic choke control device (technical term for the choke heating element and bi-metalic spring). It is the opposite of a return spring. Its' function is to force the choke closed in the condition of cold engine temperature. As the element warms the bi-metalic spring, the tension is reduced, allowing the choke to open. Additionally, there is a vacuum pull-off device that enables the choke to be momentarily opened during partial/full throttle condition, before the choke control device is fully warmed.
What has been described as a problem is entirely the result of warming up the car without driving it. When everything is normal, eg.: functioning properly, starting with relatively cold temperatures, the idle will climb as discribed, as the engine begins to warm, and the fast idle cam is holding the throttle open. When the accelerator is depressed, it takes the throttle stop adjustment screw off the fast idle cam, allowing the cam to drop. Then the whole process begins again, the idle climbs... It will only cease to undergo this process after the choke heating element has warmed the bi-metalic spring to the point that there is no longer tension on the throttle.
Letting a cold engine idle is the worst thing anyone can do to an engine, and the atmosphere.
This is from someone who's been an official Volkswagen Master Tech since 1971.

Mon Dec 20, 2004 5:57 pm

I've heard both opinions on warming the engine up and it sounds like the safe thing to do is start the car and drive it gently (low rpm's) for a few minutes and then you can drive it however you want. I've been doing this and everything is fine.

Mon Dec 20, 2004 6:43 pm

warmed oil performs better, and cold oil at high rpms can promote damage. So, I guess taking her easy for the first couple minutes seems like a good alternative to a warm up.

Mon Dec 20, 2004 10:15 pm

You want to run lower viscosity oil in the wintertime to avoid problems like blowing out oil seals and coolers from excessive pressures, right?
I've been starting the car up and driving right off for thirty-six years without trouble. I've racked up as much as 212,000 miles on an aircooled engine, over 100,000 on several. I come from a large family of Volkswagen owners, most of who have done likewise. My '87 Jetta currently has 248,000 on it, and the cylinder head has never been off. Most of the car is original. Same with the wife's '88, which has 197,000 on it.
From the technical aspect, the notion that a warm engine performs better is absolutely correct. How do you achieve that status? Think about it.
An engine is going to warm up a lot faster at driving speeds, under a load, than at idle.
I didn't just make this shit up.

Tue Dec 21, 2004 7:28 am

Sorry, I didn't proof read my reply. I meant throttle return spring. I'm not going to get into a pissing contest as far as warm up goes. I too am a VW factory trained master registered technician (although moved on to a new career) and have had air cooled cars in the family since 1967, driven air cooled cars exclusively since 1979 in Northern Illinois.
I recently retired my 74 standard beetle at 512,956 miles after it gave up on it's fight against rust.
The longest mileage engine that I built for it went just shy of 277,000 miles on a rebuilt German case before it cracked behind #3 cyl. The crank, cam and heads went right back into the next engine after new valve guided and general clean up.
When the 74 was cut up, I started alternating driving the '65 that we first bought in 1973, and a new mexican beetle.
As I stated, letting a car warm up to the point of sitting for minutes on end is wrong, however when you type "turn the key and go" on a public forum where quite a lot of younger and new VW owners look for advice is dangerous. I'm sure you don't mean, turn the key and drive right off like the car has been running all day. My assumption is you mean you don't let the car sit and idle for 5 minutes. I don't either, but as I drive the car in temps as low as -25f ... 30 seconds max to let the oil get circulating and the lower end splashed is what it takes.
"drive and enjoy your VW daily"

Tue Dec 21, 2004 10:37 am

my car drives smooth as hell after those five minutes.anything less and it just wont perform as i feel it should. maybe you guys are right but i know my car and id rather hear the purrrrrrrrr than a gang of backfiring. thanks for the info though it helped me figure it out. :twisted:

Tue Dec 21, 2004 11:54 am

That being the case, it sounds like you need to adjust the choke a little richer. If the choke is set so that it doesn't close enough it will also open too fast and give you the trouble you describe.

Mon Dec 27, 2004 5:20 pm

I come from a 20-year motorcycle background, so in my experience which includes a 30 year history with my 74 std, never let the engine run with the choke on for more than 20-30 seconds, on any vehicle, period. You leave it on any longer and you're just opening the door to fouled plugs and harder starts when its cold.

My technique - start the car and run it til the idle smooths out, usually within the 20 seconds above and then start driving slow. The oil is already circulating at that point, plenty of time to coat surfaces, and we all know motion creates heat, so as long as you dont hammer it, it should do fine "warming up" going down the road. Works for me on all my air-cooled vehicles including my motorcycles.

Mon Dec 27, 2004 6:08 pm

well the majority has spoken and i will try it. thanks for the info