Dear friends / Amici barchettisti

I have som serious engine problems with my orange b. and need som really good advices!
Problem as follows:
Doing renovations during the winter, new camshafts, brakes and more. Changed bearing in the alternator could,t stand the whining anymore, the job was a real challenge.
So far so good, ordered a time for MOT (Besiktning in Swedish).
and on the way the injection lamp begin flashing (not at steady light just a erratic flashing, engine cuts out.. restart, and drive for a few hundred meters then again it cuts. (ends up towing the b to my house instead).
Once home again I started the faultfinding, jacked up Fiat ECU Scan started and the results was, text below from Fiat ECU Scan:

RPM/TDC signal anomaly:
check
-harness connection state
-sensor
-continuity and sensor resistive value (500/700 Ohm at 20 C). between pins 33,41, 35 of the ECU wires bundle connector and pins 1,2,3 (shielding) of the sensor connector; moreover, check the insulation of the two grounding conductors, while pin 3 of the connector has to be grounded - signal emitted from the sensor (between pins 33 and 41 of ECU) with the engine started or during the starting attempt, by means of an oscilloscope.
The reason for this fault is Value too low
The current status of the fault is
The error counter value is 20
Jacked up the b, removed the RPM sensor (situated right under the starter) checked it and it appears that the cable was damaged, may have happened when I was poking around in that minimal crowded space to remove the alternator, (had to take out the starter before the alternator).
cut away the cable, soldered on a new, measured the sensor and it seemed OK, giving readout on the multimeter (500 + - Ohm)
Restart, grinding on the starter for a while and the engine comes to live again, then results from ECU scan:
81 RPM sensor no signal
Tore away the timingbelt cover and visually inspected the TDC sensor situated next to the exhaust camwheel, and it looks good to me!
I just been checking the wire harness between the RPM sensor and the TDC sensor to the Hitachi ECU, no problems with the conductivity = OK.
(Disconnected the ECU before of course).
How common is it to RPM/Crank sensor stops working, have any experience with this error? Maybe I´ve smashed it when I removed the starter?
And the TDC/Cam sensor any experience with malfunction here?
I´ts a Hallsensor and cannot be measured with a multimeter.
Thinking seriously to get and connect an oscilloscope, check the signal pulses from those damned sensors, or should I just order a new RPM sensor?

Test again with ECU Scan new result, text below from ECU Scan:

Phase signal anomaly:
Check:
-continuity and insulation on the conductors from the sensor connection to the ECU wires bundle connector, and mainly
a) pin 2 sensor - pin 34 ECU
b) pin 3 sensor - pin 42 ECU
- positive supply from the ECU relay for the sensor (12 Volt), ignition ON, on pin 1 of the sensor connector.
- signal emitted by the sensor between pin 2 and the ground, by means of an oscilloscope (square wave) the engine started or during the starting attempt.
NOTE: the lack of this signal during the engine functioning causes the lighting of the anomaly lamp in the board, while in case the signal is absent during the starting phase the engine does not start.
The reason for this fault is Open circuit
The current status of the fault is Impact occurred
The error counter value is 1

Any good advice would make me in a better mood!

Hej Cugel,

it's not common for these sensors to break, but I've seen some in others engines.
First that comes to my mind, is the camshaft work. Is there any possibility, that the timing might be off? And was the camshaft exactly the same as the original one, or from a different engine? Did you replace the variator or the camshaft pulley and re-do the timing, or just use timing marks?
Any possibility that the timing sensor was damaged during the work?

Both cost around 20€ from ebay, so if you have checked the wiring and are 100% sure that the timing is spot on, then you might want to change the sensor just and see if it helps.

I assume you have the engine manual already, but if not here's a copy: https://www.dropbox.com/s/fxx705c6qoktzpj/10[1].2 Engine.pdf?dl=0

Hello Ilkka, first of all thank´s for your advice, "Kiitos avusta ja neuvoista"

My thougts is that i damaged the TDC sensor behind the camwheel, i remembered
that the metalring with "gaps" (for the hall-sensor) jammed between the sensors posts
and maybe I was bending to much..

It´s not easy to check the both sensors.
RPM-Sensor = Measuring the Resistance: 570 % 57 ohm at 20°C seems OK
TDC-Sensor = Hall type, need a oscilloscope for this, witch I dont own..

Althought I run the free wersion of FIAT ECU Scan and it says that this fault is intermittent/present, RPM/TDC sensor anomaly. time to change the TDC-sensor.. and maybe I change the RPM-sensor just to be sure.

The new camshafts comes from a barchetta, and I use FIAT`s camlocks specified, but instead use the FIAT/ALFA TDC kit on cylinder 1, I use the marking on the flywheel, corresponding to 0" mark on the bellhousing = you cant miss the absolute TDC.

Time to start looking for new sensors