Technical Crankshaft sensor/ECU

[chink]

I have a 2003 punto 1.2 5000000. It turns over but refuses to start. Diagnostic code P0335 RPM Sensor came up on the test. I have replaced the Crankshaft sensor and Cam sensor, checked the wiring for breaks and even fitted a used self-coding ECU that I got off eBay. Timing and fuel have been checked.
The mechanic says that power is getting to the coils but the circuit that should "drop out" is stopping the spark.
I've ordered another crank sensor in case the new one is faulty but other than that I'm lost.
Any ideas?

 

[judderbar]

I have a 2003 punto 1.2 5000000. It turns over but refuses to start. Diagnostic code P0335 RPM Sensor came up on the test. I have replaced the Crankshaft sensor and Cam sensor, checked the wiring for breaks and even fitted a used self-coding ECU that I got off eBay. Timing and fuel have been checked.
The mechanic says that power is getting to the coils but the circuit that should "drop out" is stopping the spark.
I've ordered another crank sensor in case the new one is faulty but other than that I'm lost.
Any ideas?

On my car the rev counter shows about 150 revs when I crank the car via the crank sensor.

Likewise I am pretty sure the free ecu testing software people are using here MULTIECUSCAN shows revs when you are cranking.

If necessary I have this crank sensor testing plan for my car:

https://www.fiatforum.com/punto-ii/429490-testing-crankshaft-sensor-ecu.html

 

[chink]

Thanks for the reply. That's all a bit complicated for me though. I believe the mechanic is going to try something similar today.

 

[chink]

After replacing all of the above I took a chance on a used crank sensor from eBay. Problem solved. The new crank sensor was faulty ?

 

[Evsraymond]

Hi Chink,

Can I ask if you had to go through any relearning process for the ECU when you replaced the crank sensor? I've recently replaced my Punto 1.2 16v with brand new crank sensor but when I turn over the engine it either revs super high (3-400 rpm) and then dies or it lapses into a very laboured throbbing idle at around 100 revs and then eventually dies as well. Does this sound familiar in any way? I'm wondering if its to do with the ECU not recognising the crank signal...

Cheers

 

[judderbar]

Hi Chink,

Can I ask if you had to go through any relearning process for the ECU when you replaced the crank sensor? I've recently replaced my Punto 1.2 16v with brand new crank sensor but when I turn over the engine it either revs super high (3-400 rpm) and then dies or it lapses into a very laboured throbbing idle at around 100 revs and then eventually dies as well. Does this sound familiar in any way? I'm wondering if its to do with the ECU not recognising the crank signal...

Cheers

When was your Punto made? A picture of the engine and front of the car is going to help. Ordinary puntos will not start if the crank sensor is not detected. Later Puntos have limp home mode and can perhaps run the engine via the cam sensor.

What fault did you have before fitting the new sensor?

 

[Evsraymond]

It's a 2001. Not sure if it has a cam sensor, or at least I haven't seen one. I would have expected the cam sensor to be on the top of the cam housing somewhere right?
I haven't used a diagnostic tool on it yet, but the symptoms before I fitted the new crank sensor were:
Taking several tries to get it started.
Poor acceleration.
Stalling at low revs once warmed up.

I have a feeling one of the coils may have gone now as the idle is extremely rough and sounds like maybe only two cylinders are firing. No white smoke or mayonnaise so hopefully not the head gasket...

Will try and post a photo of the engine when I get a chance