Hi everyone,

Further to my thread about my sei cutting out, I thought it was due to operating the brakes, but that appears to not be the case.

As fingers alluded too it may be the rad fan, now this doesn't come on, I think that the car stalls when it tries to start the fan. But I am not sure.

Luckily I have an calibrated ir temperature monitor, so was able to measure temps in the engine bay. The rad was about 90 degrees with the top hose about 85 degrees. The engine varied but was approx 70 degrees.

So the car isn't overheating. The fan doesn't appear to be seized, so what else could it be?

I have heard That the mpi cooling fan arrangement is more complicated than the spi.

The ecu controls it? Does it use the engine temp sensor as a reference? Where is the controlling relay?

Is there anything else it could be?

Cheers

I've changed 2 crank sensors that have only failed once the engine is up to temp. The sensor bracket is bolted to the block, once the heat gets to the sensor the increased temperature causes it to fail/behave erratically when the sensor is faulty.

I noticed this recently on my current set up because I kept losing synchronization on my ignition input while I was doing some tuning once the engine was warm. Strange fault easily overlooked, fitted a new sensor problem solved. Also had the same issue on another cento, seems like a common issue. Worth a try if you can get your hands on/borrow a spare to test it.

Should show up in on a code reader but mine didn't bring the EML on and was insanely intermittent. Luckily with real time monitoring it was easy to spot.

Ah, that's interesting!

Are all sensors the same? I have one knocking around that came from my old spi sei, would allow me to test the fault.

I have the lead and software to read the spi ecu, what lead and software is required for my mpi? It's a Schumacher model with a micro ecu I think.

SPI ones are the same.

They are the same but the SPI cable is 105mm shorter, if you can make it reach it will be good enough to test. I'm not sure if it's long enough for a permanent fix, if it's not extending it isn't that straight forward as it's shielded to prevent interferance.

Just to update,

I found the fan relay and shorted out the output terminals and the fan runs fine.

So I am thinking that it is the crank sensor that is causing the issue, it is only happening when slowing down from a higher speed, ie off a motorway. I guess that heat soak from slowing down is causing the crank sensor to become intermittant. It also does it when manoeuvring, although that may just be me stalling it!

Will report back once I have found time to fit my spare SPI crank sensor.

Sounds more like a sensor harness problem than the actual sensor. Sudden deceleration or lifting off will cause the engine to shift on it mountings somewhat which might displace the harness or connectors especially if they are routed incorrectly...I would pull on the harness to the various sensors while the the engine is running to check this out...especially the crank sensor connector and harness...breaks in wiring around stress points is not unheard of

A dodgy earth would do the same.

You might get a single jumplead, run it from battery negative to somewhere solid and metalic on the engine/box and duct tape it roughly in place.

If the problem disappears, it's an earth issue.

Hi,

Thanks for the replies, a loose connection is also a possibility but the wiring loom seems to be in good condition, plus the car will stall what not moving ie when parked up.

Anyway I have fitted the spare sensor I have, I think it was the issue as the original sensor came apart and had to be smashed out. The bracket was also pretty corroded! It's made of Ali which will make heat soak more of an issue. So am hoping it's fixed the problem!

Finally the sensor I had from an spi was the same length as my mpi one? So maybe there are different mpi variants? This is a fairly early mpi.

Thanks for all the help guys

At some point they may have decided to re-route them. I think the Punto MPI ones are a different length.

I only noticed because there are two diiferent parts on Shop4Parts and when I cross refferenced the Fiat numbers to see the difference I realised they were charging an extra £7 for 105mm cable as the electrical specifications of both the sensors are exactly the same.

http://www.shop4parts.co.uk/?name=s...&secondary=133&opts=49&btnViewProducts=Search

Just to confirm,

The stalling issue seems to have been fixed.