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Discussion Starter #21
Well if you were cranking the engine and its not starting they should be wet assuming you have fuel in the tank and your fuel pump is working. Canyou hear the pump priming when you turn on ignition ?
Yes the pump is priming..
 

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Then the sensor is not working, or the wiring is damaged. if the other crank sensor still did something, try that. You should be getting very good at switching them now
 

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Discussion Starter #25
Then the sensor is not working, or the wiring is damaged. if the other crank sensor still did something, try that. You should be getting very good at switching them now
Oh I had cut the wire of the old sensor cuz i couldnt get it out of the clips xD but no worries ill solder it back together and try again. And yes I have gotten better at it now haha
 

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If you did not disconnect the battery there is a chance when you cut the wires for the old sensor you may have caused a short circuit, even if the car was not on. Hopefully just a fuse blew if that is the case and a replacement of the fuse will remedy the problem.

Flooding an engine is when the car puts in too much fuel into the combustion chamber, sometimes because of overcranking and the chamber fills with fuel. If it is full of fuel there is not room for the air and the spark which are the other components needed for combustion. If the spark plugs were wet (with fuel) that means that the engine was flooded. Removing the plugs can allow the fuel to slowly evaporate if that's the case.

If the car was starting before why did you change the sensor?
 

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Discussion Starter #27
If you did not disconnect the battery there is a chance when you cut the wires for the old sensor you may have caused a short circuit, even if the car was not on. Hopefully just a fuse blew if that is the case and a replacement of the fuse will remedy the problem.

Flooding an engine is when the car puts in too much fuel into the combustion chamber, sometimes because of overcranking and the chamber fills with fuel. If it is full of fuel there is not room for the air and the spark which are the other components needed for combustion. If the spark plugs were wet (with fuel) that means that the engine was flooded. Removing the plugs can allow the fuel to slowly evaporate if that's the case.

If the car was starting before why did you change the sensor?
I only disconnected the negative terminal. Would that still cause a fuse to blow?
I want to replace it because the motor control failure engine check light was coming up every now and then.
 

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I want to replace it because the motor control failure engine check light was coming up every now and then.
Did you scan it to see what was causing the errors?
 

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Discussion Starter #29
Can I still scan it with OBD2 if its not running? I tried doing that but didn't seem to work, unless I'm doing it wrong..
 

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You can still scan but being a European car, it uses EOBD, not OBD2. Nonetheless, they are very similar.

What were the original codes which has you deciding to change the crank sensor?

Is the induction trunking refitted correctly and the MAF sensor refitted and plugged in?

Did you touch anything on the battery positive terminal or disturb anything related?

Did you change the crank sensor from on top of underneath?
 

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Discussion Starter #31
You can still scan but being a European car, it uses EOBD, not OBD2. Nonetheless, they are very similar.

What were the original codes which has you deciding to change the crank sensor?

Is the induction trunking refitted correctly and the MAF sensor refitted and plugged in?

Did you touch anything on the battery positive terminal or disturb anything related?

Did you change the crank sensor from on top of underneath?
So I should get a EOBD to be able to scan?
I didn't scan beforehand..

Yes the induction trunk is fitted back the same and I hadn't disconnect the MAF sensor at all I just left it on the trunk. Would an improper fitting cause a no start? If so what kind? Just to know..

Don't think I did disturb anything on the positive terminal at all. The only other connections I disconnected was the throttle body connectors and sensor and ground which I've reconnected them all back properly.

I changed from up top. I refitted a second time now to make sure the crank sensor was all the way in. I've took out the old o ring also.
 

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I would still check the fuses just incase. if the battery was disconnected no short should have occurred.

Try disconnecting the negative terminal on battery. Leave it off for 15 minutes. Reconnect, turn the key to the second position and see if you can hear the throttle body make it's hum/whine. I would double check that connection with the throttle body.
 

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You should have the appropriate diagnostic tool before started working on any car produce after 1990, especially when you're working on sensors. You can buy a Fiat KKL to USB cable for less than 20 euros and use it with MultiEcuScan software(There's a free version, but I'd recommend paying for the full version) and that would give you the dealer level diagnostic capability.

With the KKL cable and MES you could read a live RPM reading directly from the ECU, if it reads 0 when you're cracking the engine, then you know the problem came from the crank sensor, whether it's a bad replacement sensor or you didn't install it correctly.
 

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To further provide information (and following advice from @mikesalfa and @botasky), the issue of starting and immediately not running is more like a fuel issue.

Check that the earth connection at the flywheel end of the cylinder head is good, as should be the earth onto the ignition coil chassis and engine ECU. That said, I think the issue is more likely to be connected with the fuel pump or engine ECU relays. It may be the relay itself or simply oxidised terminals inside the multi-block connector. These are located in front of the battery. Be aware that sometimes less than scrupulous people put these multi-blocks back in the wrong places.

Unfortunately in this case it seems that failure to correctly diagnose the original problem correctly and perhaps performing the work has allowed an underlying fault to fully manifest which has resulted in the situation. With that statement in mind, I'd also check the main engine relay and fuses. Any high resistance connections could give the type of effects being experienced.

The issue is our cars do not have the relays and fuses in a sealed box which means all these critical circuits are exposed to weathering effects. I think that failure to maintain these things (because people just do not know) are probably the most common threads in this forum now.

Did your scan tool connect to the engine ECU before and if so when?
 

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Discussion Starter #35
You should have the appropriate diagnostic tool before started working on any car produce after 1990, especially when you're working on sensors. You can buy a Fiat KKL to USB cable for less than 20 euros and use it with MultiEcuScan software(There's a free version, but I'd recommend paying for the full version) and that would give you the dealer level diagnostic capability.

With the KKL cable and MES you could read a live RPM reading directly from the ECU, if it reads 0 when you're cracking the engine, then you know the problem came from the crank sensor, whether it's a bad replacement sensor or you didn't install it correctly.
Makes sense. Thanks for the tip!
 

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Discussion Starter #36
To further provide information (and following advice from @mikesalfa and @botasky), the issue of starting and immediately not running is more like a fuel issue.

Check that the earth connection at the flywheel end of the cylinder head is good, as should be the earth onto the ignition coil chassis and engine ECU. That said, I think the issue is more likely to be connected with the fuel pump or engine ECU relays. It may be the relay itself or simply oxidised terminals inside the multi-block connector. These are located in front of the battery. Be aware that sometimes less than scrupulous people put these multi-blocks back in the wrong places.

Unfortunately in this case it seems that failure to correctly diagnose the original problem correctly and perhaps performing the work has allowed an underlying fault to fully manifest which has resulted in the situation. With that statement in mind, I'd also check the main engine relay and fuses. Any high resistance connections could give the type of effects being experienced.

The issue is our cars do not have the relays and fuses in a sealed box which means all these critical circuits are exposed to weathering effects. I think that failure to maintain these things (because people just do not know) are probably the most common threads in this forum now.

Did your scan tool connect to the engine ECU before and if so when?
I was also thinking of checking the multi block and the relays of the ECU. I will give those a look. The ground connections are good as I've refreshed them by scrubbing them with wire brush. And no I didn't connect my scan tool beforehand, which I know now to do so in the future!
 

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Discussion Starter #37
Hey guys so I've managed to solder back the wiring of my old crank sensor and refitted it back and my car fires up straightaway! The "motor failure" check engine came on but went away after half an hour of driving. I realised the new sensor I had purchased was in fact not OEM (my mistake) so now I've purchased a new one by Bosch. Thank you guys for all the great tips, really appreciate them. I've learned a bunch!
 

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Great news. Thanks for keeping us updated. Now you just need to give the old car a scan to see what's throwing up the code.
 

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Do be aware that some fault codes do not activate the engine check light. Sometimes they can be an indication of a developing fault so a fairly regular diagnostic scan can help with taking preventative action before it becomes critical.
 
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