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Help motor goes off for 30 minutes and on again after

2698 Views 12 Replies 8 Participants Last post by  Igor Barbaros
i own a 2001 smart 4two cdi/diesel.

My car stoped after few minutes driving at a red sign and only started after 30 minutes. And i've been on that cicle for a month allready.
During that time the electrical part its working and when i turn the key everything's fine but the motor doesn't give any sign.

Now their saying that i have to change all the transmission. It's expensive and i have my doubts cause i dont have any problems in trasmission and it doesn't seem to be the problem.

Please help,
i'm desperate and the transmision money it's almost the comercial price of the car

Paulo Inacio
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I am not sure I can help you, but did your warning light come on? Do you have access to a code scanner that can read diagnostic codes (such as a Scangauge)?

It may help others understand the issue if any fault codes can be detected.

Hope you can get this resolved!

Check all your fluid levels (oil and transmission) there may be a level sensor shutting the system down.

When it is in its 30 minute shut down does the starter motor turn? If yes I would check fuel flow/filter/pump, if the answer is no then look for sensors that may cause this.

Your repair people say “Replace the transmission” what is their reason?

Does the car come to a quick stop (seize), but then that doesn’t make sense you would be starting in neutral.

Just a thought

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The engine start after a 30/40 pause.

The reason they want to replace the transmission is based on some kind of sensor that detects that the discs are on their maximum tune. I'm not totally convenced and its a expensive reparation.
It sounds like a fuel filter is clogged, it would be the first thing I would check as far as the stalling is concerned.I had this happen to me on a truck I had a long time ago, the fuel filter was full of rust, when I drove faster the fuel flow would clog it up, when the pressure stopped the rust fell away from the filter media.
To me, I would look at replacing the fuel filter, and does the Smart have a "Coil" of some sort.
Either one would give these symptoms.

The car is too new for a coil type issue, so a simple fuel filter replacement would be my first thing to do.
Doing stuff like this is cheaper than paying a tech to trouble shoot.
Fuel filter is in the gas tank, there is no exposed filter I know of.
It doesn't sound like a fuel problem. It sounds like something electrical. I would guess the MAP sensor is sending a wonky signal as the engine warms up.
It doesn't sound like a fuel problem. It sounds like something electrical. I would guess the MAP sensor is sending a wonky signal as the engine warms up.
What and where is a MAP sensor
The MAP sensor is "Manifold Absolute Pressure." It measures the manifold air pressure and sends the signal back to the ECU (Engine Control Unit). The data provides the air flow rate which is used to calculate the amount of fuel that is fed to the fuel injectors to provide the correct ratio between air and fuel for optimum combustion.

Here's a good explanation of the function:

In Smart 451s the part number is 451-820-69-10 (please double check me on that) and is located at the front of the engine below the exhaust manifold.
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Can the mat sensor shut the engine off after it is cold started after running for a couple of minutes, and then not allow a start again until the car cools off again
Yes, it can.

It could also be a failing fuel pump, something failing in the ECU or SAM.
Kinda sounds like a bad camshaft position sensor
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