Seat Toledo engine stalls when warm

Question

I have a 2001 1.6 16v Seat Toledo.

Short story:

My car randomly stalled when the engine warmed up to operating temperature and I could not restart until it cooled down. A mechanic cleaned the throttle valve. After a month when the coolant liquid warmed up to 90C the engine stalled when idle. I can avoid stalling by keeping my foot on throttle and if the engine stalls I can restart it. Seems that the throttle valve cleaning had some effect but it did not solve the problem. The diagnostic tool does not show any error codes. What could be the problem? It can be the EGR valve?

Update(the whole story):

Let’s start at the beginning of the story. About 3 years ago while I was driving the car (it was in gear) the engine died, it had no power. It was like I would release the gas to use the engine break. I shifted down 2 gears to rev up the engine, after 3-4 seconds the power came back. When this happened the check engine light came up. The error code was caused by an EGR valve failure. So after the engine power came back everything was fine. But the phenomenon started to appear again and again more frequently and once the power did not came back and I was unable to restart the engine. I had electric power. When the engine totally cooled down it started as nothing would happen. I took it to a mechanic, he said that the stalling was caused by a stucked throttle valve.

The phenomenon with the stalling engine disappeared for 3 years, when the last month the engine stalled right after it warmed up. The engine did not start until it totally cooled down. After the restart the idling was not stable for the first 20-30 seconds. After that it became smooth. This time were no error codes. I took it to a mechanic again (to an another one), they cleaned the throttle valve. The car runned fine for one month. Exactly when the engine reached the operating temperature, it stalled in neutral with the throttle released. This time I could restart the engine and I could avoid stalling by pressing the throttle. No error codes. After the engine cooled down at the first start with cool engine the idle was not stable for few seconds. After 10 seconds it became stable. • There are no strange noises coming from the engine before or after it stalls. • There is nothing unusual vibration before the engine stalls. • I did not felt any burning smell. • The connection of the battery terminals are good, they was cleared of corrosion. • The car has a manual transmission.

Thank you!

Zoltan

Answer 1

This can be many different things ranging from a automatically resetting breaker to overheating electronics to vibrations and loose wires to hydrolock especially if your fuel line is loose and sitting somewhere it shouldn't be.

• When it stalls do you still have battery power or is everything off till you turn the key to off?
• or or is everything off till you wait till it cools off
• you have 2 conflicting things in your questions can it or can it not restart right away?
• do you notice anything else happening when it stalls?
• is your car an automatic or manual?
• does it vibrate a lot?
• are there any strange smells like burning wires?
• how are your battery terminals and connections?
• how long do you need to wait generally
• when did this start happening

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ok well a stuck closed throttle valve should allow the car to idle still and a stuck open one would cause the car to rev. Can you take off enough parts to see the throttle body with the butterfly valve? Does it look dirty possibly covered in oil? Make sure the car is off if you do this and you will need to open it with your fingers to see the back side of it. But this doesn't make sense with needing to wait till the car cools down.

it is not getting excessively hot is it? and the radiator fan turns on like normal right?

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This is a strange one and I do not think the car warming up has anything to do with shutting off. I think it may be a length of time issue instead but I might be wrong in this assessment.

Things to do next time it shuts off:

• if it predictably dies this these will be easier to perform
• next time it shuts off check to see if your fuel pump is pumping should be a buzzing sound that will stop when the system is pressurized.
• check the engine for spark. pull the plugs hold one against the block and crank if the plugs spark great.
• if both those check out then you may have a vacume leak that only happens when the engine is warm. As it is heating up see if you can hear a hissing sucking sound from anywhere.
• check your fluids is there any water in the oil or does the water or oil go low?

I am not convinced that it is the butterfly valve in the throttle body. but it could be a faulty sensor. You can try unplugging the throttle body sensor cable and see if the car then starts. if it does than it may be the sensor is reading wide open and the car is giving too much gas. but this should be cross checked with the mass airflow sensor.

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conceivably the position sensor is probably just a light sensor but it could be a potentiometer. when it was cleaned some of the cleaner may have gotten into that plastic body and wiped out some gunk on it.

Below is a potentiometer from a throttle body it should similar to the one you will find in yours. It looks like this is the preferred way of finding throttle position.

what you might want to try is taking off the plastic cover of the throttle body and spraying everything in there clean using electric contact cleaner. then regrease the gears and shafts and see if it works. if you want to go one step further then take it all apart and clean the contact pads and the contact points that touch them using some 100% isopropyl alcohol or as close to 100 percent as you can get.

if it does have a light sensor then you will need to clean the cog and the sensor. Use electric contact cleaner or isopropyl alcohol and a tooth brush. below is a generic example of one.

as the cog breaks the light beam it will register a 0 and when the light hits the sensor again it registers a 1. By counting 1's and 0's computers can keep track of where things are.

This may not be the solution but with the clues it is a start.

Answer 2

The cause of the problem: Well, the problem was fixed about 2 years ago, so I can tell 100% sure that the cause of the problem was the EGR valve. The EGR valve is electronically actuated and had an intermittent failure. When it was checked with a diagnostic tool it just worked fine. That is why the defect was not identified earlier.

After the EGR was changed the engine worked fine. Here the story should end but... the P0402(Exhaust Gas Recirculation Flow Excessive Detected) error appeared. The mechanic said that I should not care about that error code(with other words: give me the money and go). After a month of research I find out that the EGR that was mounted in my car is not compatible with it. A potentiometer gives a feedback voltage which corresponds to the valve position, this voltage was not between tolerances. The calibration(basic settings) of the EGR could not be made because of it. The minimum position voltage was out of range(it should be between 0.3-1.3V and it was reading 1.9V). After changing the EGR valve to to the OEM the basic setting could be made and the check engine light disappeared. (The mechanic did not try to recalibrate the EGR after changing it, otherwise he should notice that the EGR is not compatible).

I hope who has this problem reads this.