engine stalls from apparent overheating

Check your idle air control valve, its bolted to the throttle body.

Not being a mechanic, I have no idea where the throttle body is... But, why would the problem develop when the engine is overheating if it is related to the idle control? Are you saying that you don't think it is related to overheating? I am relatively certain that it is related to overheating, despite the temp gauge not indicating that... Thank for you response.

If the gauge isnt showing a problem, why do you think its overheating?

I need to find the owners manual, but I seem to remember the gauge being oil temperature. The problem started several weeks ago when I was sitting in a world-class traffic jam...stop and go for over four hours. I developed a hunch that it was overheating but would restart when it had time to cool down. During colder weather it has been doing ok... until the past couple of days when the weather has been much warmer. Today it was in the mid-70's. I hope I am wrong about it being related to overheating, but that has been my thinking. I need to find the owner's manual and confirm what the temp gauge actually is reporting -- oil or water. Thanks for your response, much appreciated.

I found the owner's manual... the gauge is the coolant temperature (as you probably knew). And there is an idiot light to indicate overheating as well.

So, you are apparently right. Although, I don't understand why the engine would start back up after it cools down if it is an idle control valve...although I suppose it might expand and contract due to heat.

Thank you for your help and for not going off on me for being ignorant. ;)

Now I need to figure out how to locate the throttle body and the control valve. Is this something I can repair myself? Is it expensive? I am pretty much wiped out financially and I can't afford to pay a mechanic...

I don't understand why the engine restarts after waiting up to 30 minutes. That is why I thought it was overheating...that it needed time to cool down before it would restart.

Please advise... thanks again.

Ok a stall when coming to a stop is either vacuum or idle air control, but not restarting until it cools off can be the crank position sensor. Is your check engine light on? If yes go to Autozone they will read the codes for free. Post all codes here.

I would focus on the overheating!

Common issue is a broken water pump or burnt out radiator fans.

With the engine at idle, turn the A/C on and check to see if both radiator fans are running.

Check engine light is not on. But, can reading the codes help anyway?

not if your light hasnt come on. Crank sensors can be heat sensitive without setting a code. To check for engine temperature I use an infrared thermometer, and aim it at your thermostat, when the fan starts, take a reading, it should be in the 220 to 224 degree range. and as exovcds said, when the a/c is turned on, the fan should come on with the compressor. Thermometer can be bought at a parts store.

I just checked the fans...they are working fine.

Now that we know there is no overheating issue, you can focus on the stalling problem.

You need to determine what is "missing" when the engine does not start.

- fuel (injector pulse)
- spark (ignition pulse)

As mentioned by Merlin2021, a faulty crankshaft position sensor can cause an engine to stall/not start.

A faulty crank sensor will cause no spark & no Injector pulse.

So when testing for spark & fuel, if you have either spark or fuel, then the crank sensor is probably OK.

Codes might be stored even if the Check Engine Light is not on, so it is always a good idea to see if codes (pending) are stored.

Thanks. One thing for certain (virtually)... it happens when the car is running hot (apparently not overheating as I originally assumed), and it starts back up only when it has time to cool down. I'll keep plugging away at finding the cause... I''ll get the codes read asap. thanks again for the help...

One more thing I just remembered to mention. I use cruise control religiously... since this problem started, my cruise control will suddenly go off while I am driving. At first I thought the engine had died, but quickly realized that it is simply the cruise control bombing out... probably not a coincidence that this issue came up during the "conk out after stopping" issue...

I had the codes read at Autozone... no codes.

I'm wondering if it is related to the cruise control, which, as I noted, has been cutting off while driving, without warning. I'm going to leave it off and see if I get better luck. Does anyone have an opinion on this? Does it make sense that this might be the culprit?

I do not think that the cruise control would cause such a failure...
especially since your issue is during stop & go traffic and not
while the Cruise Control is active.

What ever is causing your issue, the ECM is not able to recognize
(hence no codes)... which will make troubleshooting more difficult.

To clarify... the issue is not necessarily during stop and go traffic. It started originally during stop and go traffic, but since then I haven't been in stop and go traffic. Now, the engine will die when I come to a stop at a traffic light, after driving long enough for the engine to warm up...then it will only start back after sitting for several minutes...the last time it took about 20 minutes before it would start back up.

The issue with the cruise control started just after the initial issue with the engine dying... so it is logical to assume that it is more than a coincidence that the two issues happened simultaneously (virtually).

Thanks for the comment. I appreciate all the help I can get.

...also to further clarify... it doesn't stop every time I come to a stop. It is totally unpredictable.

Ok, thanks for the clarification... sorry if I misunderstood your
earlier post(s).

Could be a throttle body issue... drive by wire, where the throttle
does not open and no longer allows air to enter the engine.

A faulty throttle body will usually set a code, and since you don't
have any codes that could be of help, it might not be a throttle
body issue.

The best time to test / diagnose the vehicle is while it is not
starting. Fuel & ignition can be ruled out quickly at that time.

If your scan tool can communicate with the ECM during the time of
"no-start", then at least you know that the ECM is powered up & working.

Older VW's had ECM relay problems, where the relay would cut out
causing the engine to die... sometimes the relay would work again
and other times the relay would need to be replaced.

I would have to check a wiring diagram, but I believe your vehicle
does not have an ECM relay... so the above was just an example.

Wouldn't the cruise control affect the throttle? i.e. when it regulates the speed, isn't it adjusting the throttle to keep the speed constant according to the cruise control setting?

I don't own a scan tool... I had it done for free at AutoZone...so there is no way I can check it while it has stopped, which is usually in busy Atlanta traffic at an intersection.

Cruise Control is an input for the ECM... so yes, the ECM then
adjusts the throttle body according to desired speed set with the
cruise control buttons.

The brake pedal, clutch pedal & cancel button all "cancel" cruise
control once the ECM "sees" an input signal from one of them.

I really don't think that the cruise control/inputs could cause
a no-start.

The most logical possibility at this time would be the Engine
Speed Sensor (crankshaft position sensor)... but even it "should"
set a code when it fails.

But the only way to know if it is a bad crank sensor, is to check
its output voltage "during the time of no-start".

A good crank sensor will produce 2VAC+ during cranking speeds.

What is the ECM?

Engine Control Module - Fuel Injection Computer

I have been suffering with this problem without any luck... but last night, the EPC light went on and the oil pressure light also
went on. I was a few hundred yards from my house so I drove on home. I checked the oil level and it appears to be ok. Also, I was told the other day that one of my brake lights is out. So I'm wondering if the multiple issues (brake light, cruise control going out, etc.) are symptoms of the same issue. ?

I have tried to research this issue online. I know I need to scan the engine codes, but it probably isn't a good idea to start the car and drive it to AutoZone. I saw something about scanning it with VAG-COM. I assume this is a software program and an interface cable that you plug in to read the codes... I can't afford it anyway...plus I believe it is PC only and my laptop is a Macbook Pro.

I have found references to all of the issues that I have when I google EPC code and oil pressure, etc. References include the brake light switch and idle issues, and oil pressure issues. Any additional input is greatly appreciated.

One more thing... this model was recalled a couple of years ago because the sunroof wasn't draining properly... I'm wondering of water has corroded a wire somewhere.

Also, this thread isn't getting traction any more... probably because I don't have the engine codes since I can't drive the car to AutoZone...

Adman,

Sorry to hear you are still having issues!

Unless someone has run-into the "exact" issue at hand, it is difficult
to determine what the cause is.

Not all "experts" here are VW Technicians, or currently working
in the trade... which can affect input on subject at hand.

I am full time employed, so I don't have time to post till after
work or weekends.

But again, the main thing being... not having run into said problem
before, will affect the amount of feedback/suggestions on repair
you will receive.

Attaching tools / diagnostic equipment to a vehicle can "catch"
glitches that can not be seen over the internet.

Engine codes: AWP for 4cyl or BDF for 6cyl (at least in north america).

Thomas

Thanks... I wasn't complaining about the lack of responses, but expressing my understanding of why. I appreciate all the responses.

On another note... my clutch is slipping. Is there an adjustment for that or is it an auto-adjust? What are my options?

Clutch is non adjustable... once it starts to slip, you can baby it a bit to buy some more time. But replacement is the only way to fix it.

I was afraid of that... I guess it doesn't hurt to continue driving it in terms of the clutch.

I just went out and started it. It started fine and no idiot lights are on. I followed the advice of someone on another site and removed/replaced the oil cap to stop the oil pressure idiot light from coming on...apparently that worked.

It probably still is not a good idea to drive it... and I assume the engine light has to be on at the time of the code read in order to produce a code...

I have an '02 GTI with similar problem. The engine speed sensor seems to be the issue. It will trip the EPC light, cause stumbling idle, stalls and problems starting as well as effect the cruise control. You are looking in the right place and you will need the VW reading program to see if this is the case. The average price of the sensor is $125 area from the dealership. Probably half that from your auto parts store.

My main issue is this. After the engine develops heat... 20 minutes or so of driving, it will stall after coming to a stop. It will not restart until the engine has had enough time to cool back down, usually 20 minutes or so, depending on how hot the weather. A mechanic looked at it the other day and suggested that is it probably the electronic ignition module...that they can "go out" when hot. He is further researching the issue. The EPC light and oil pressure light have only gone on once and not since. I am limited to using the car for very short trips.

My money is still on the crank sensor...

Is the crank sensor subject to heat?

Nevermind... I see above (scroll up) that it is... sorry.

Are the crank sensor and speed sensor the same thing?

No speed senzor is on the transaxle crank sensor is on the engine block at the crank sensor.

The crank position sensor is sometimes referred to as the engine speed
sensor. This was a suggested part within the first 4 posts.

Located to the right of the oil filter, mounted to the block.

Thomas