Why does an 88 Volkswagen Cabriolet die every time you push in the clutch while slowing down to stop?

Answer 1

The engine idle speed is set too low. If the engine starts and runs, but stalls as you described it, you need to have the engine tuned up.

A proper tune up will find and correct this problem, and also results in a cleaner burning engine which will help all of use breath a bit easier by reducing your contribution to air pollution.

your clutch is probably not disengaging all the way or your idle is too low

Here's the real problem, and it's not idleIt's timing. Volkswagens are notorious for this.

Most of you young whippersnappers grew up on cars with "limited advance/retard range" on the distributor. My wife's got a Toyota (she refuses to drive anything from Volkswagen even if it's new; I don't know why) and you can only change the timing a small amount. If the distributor holddown bolt comes halfway out, allowing the timing to go to full retard, the engine will still run. It will run badly, but that's a different issue. On a Volkswagen, you can turn the distributor completely around. Eventually, the timing will fall out of the range the engine will run in.

"But it only does it when I push in the clutch while slowing down!" Yup. That's exactly right. There is a device in your distributor called the advance mechanism. An engine has to change its timing as it runs, and the advance mechanism does this. When you get into the gas, you've moved the timing into the range the engine will run in. (You've probably also noticed you have to step on the gas pedal to get it to start. What you're really doing is advancing the timing with the accelerator. A fuel injected car that's running right should never need you to step on the gas during startup.)

There's two ways to fix this--the right way and the Muldoon way. (Muldoon was a mechanic John Muir talked about in "How to Keep Your Volkswagen Alive." He lived in Carson City, Colorado, and he was renowned for helping people fix their cars enough to get them as far as they needed to go.) The right way is to get the car tuned up--they'll set the timing and you'll be good to go. The Muldoon way requires a 10mm nutdriver. Put someone in the driver's seat and have them start the car. Now, with the hood up, loosen the distributor clamp and turn the distributor just a little, iirc clockwise. You'll notice the idle sped up--the timing advanced. Turn it just a little the other way and the idle will slow down. Now turn the distributor some and have your partner take their foot off the gas. Reach over to the accelerator and rev the engine up. Hold it to the count of ten, then let go--don't ease the accelerator closed, just let it snap shut. If the engine tries to die on you, advance the timing a little more. When you get the timing to the point where the engine idles good and it won't die when you get out of the gas, you've got it.

Oh yeah...make sure you get that fixed right after you do this.

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I had the same problem with my 90 Cabrio.

And it had nothing to do with timing. It is the idle control unit, which is mounted in the engine above head. It's a cylindrical shaped unit about 7" long and connects to two hoses and a wire connector. These are prone to failure. Unfortunately they cost around $200 each!

So try to locate a used one. Replacing this only takes a couple of minutes and a flat head screwdriver. Perhaps your problem is due to timing as the answer above suggests. But in my experience (owned close to a dozen VWs by now) timing is not the answer. In my case anytime I'd step on the clutch the tach would show the RPM drop so low that the red light for the battery would momentarily come on. Sometimes it would wave up and down till it idled normally again. But often the RPM would drop so low as to stall the car. Annoying and dangerous. i tried a couple of these from my local wrecker till I found one that worked. It cost 1/10 the price of a new one and now the car runs fine. Hope this helps

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For anyone coming across this via a search: A 1990 Cabrio(let) is Digifant; the 1988 in question is CIS and does not have an idle stabilizer valve (aka ISV) as the 1990 has. Instead, the '88 uses an idle boost valve (2 if A/C is installed), which is partially controlled by a relay.