I am in South Africa where we sometimes experience very hot weather. If my Barchetta is running normally, and the outside temp reaches 35degC and above, the car suddenly cuts out, and only restarts after 20 to 25 minutes or so, and then cuts out again after about 2kms. I am told this could be the crank sensor. Any advice please - how do I find this sensor? - Could there be any other cause for this? I was told to replace my water temp sensor, but this hasn't cured the problem. This can be frustrating!

you could try hanging it on a computer to read out engine faults. but in africa this might be a problem

I once had this kind of problem on My turbo'd Barchetta when in Hot weather,
It turned out to be excessive under bonnet heat that was entering my filter and and playing with the air maff censor.

Just an idea if tou have an after market induction and re positioned maff.

@ bollie 69, thanks - unfortunately the Fiat dealerships here cannot do a computer analysis because they did not import the Barchetta software - they tried with the Stilo and Grande Punto readouts but were inconclusive.
@ KC3, thanks for the suggestion, I will have a look and see if that is possible, are you saying I should try an after market air mass meter?

Hiya! All I can say is that, as soon as the car, mass censor cooled the vehicle would start. I re positioned it, added some shielding to the exhaust manifold and it solved my problem.

Another simple suggestion to try is to try running the car with the bonnet/hood propped open on the safety catch (I would also fit an extra tie down just in case).

This should let cooler air directly into the top of the engine bay. Heat soak can affect not only MAF but other components as well.

Regarding the crank or any lower mounted sensor then they are unlikely to be quickly affected by an open bonnet/hood as 1) heat rises and 2) the engine mass will retain and stabilise directly mounted and close coupled sensors.

Thank you, S130 - Are any of these parts able to be removed from the car and bench tested 'to heat destruction' i.e. to test if they cut out under applied heat? It seems to me that would be the easiest way. My problem is that this event occurs only once or twice a summer, so there would be a lot of inconclusive guessing. A Johannesburg freeway is not the place to break down, there's too much traffic to allow a relaxed stop to wait for everything to cool down :bang:

If it is only happening once or twice a summer then I can understand that you would want to reproduce the problem on the bench.

Bench testing is no doubt possible but I would adopt a different approach.

1) determine which sensors/components are likely to be causing your problem. Two we have thus far are the TDC and MAF. I would suspect the crank/TDC sensor is the most likely but as KC3 has this happen with the MAF then it would be silly to ignore it.

2) Find their connectors

3) Check their connectors for decent connections and lack of corrosion and no loose female connections

3) Measure their resistances across all possible combinations and multi-meter lead polarity combinations. Do this for cold and hot. Make a note of the readings and check values with any technical information available

4) Keep notes & multi-meter in the car

5) Next time it happens make the same measurements again and check results against original ones

Hopefully if and when it next plays up on you can quickly find the most likely culprit.

S130 - Thank you again, this seems to be the best way to go. I am afraid however that I will first have to try to learn how to use a multi meter, but will definitely go that route. Once all the parameters have been recorded, I will have a go with an ordinary hair-dryer to see if I can simulate failure of a component under heat stress, or at least record any changes as they happen. It would be interesting if more Barchetta owners other than KC3 have had similar experiences, although I imagine these are universal issues, not limited only to Barchettas. Thanks again!

As you new to multi-meter usage I need to explain something about why I talked about swopping the meter leads around.

To measure resistance a milti-meter has a battery in it. It uses the battery to pass a current through the external component under test and measure how much current is allowed to pass.

So with a simple 1000 ohm resistor to test you can swop the meter leads around and it will make no difference to the meter reading.

However if the device under test has a diode or other voltage polarity sensitive device then the reading taken will depend on the orientation of the meter leads.

Simple example:

______ 10K resistor_____Diode

A o-------\/\/\/\/\/------|>|------o B

If you put the Red multi-meter test lead on terminal A and the Black lead on B then your meter will show about 11K ohms (11,000).

If you swop the leads around to Red on B and Black on A then you will get no reading or a very very high reading.

With the above circuit current will only pass if Termnial A is Positive with Respect to Terminal B.

With multi-meters when in Resistance measuring mode then the Black lead is Positive

Thanks S130 - When I get a multi-meter, at least I now know where to start. However, if it still doesn't make sense, I know someone who has one, and he will run me through the obvious tests I have to do first. A new skill at 70 like this one is a nice challenge, thanks!

s130 said:

With multi-meters when in Resistance measuring mode then the Black lead is Positive

Click to expand...

Update to my own post as too late to edit.

I should have said "With modern multi-meters when in Resistance measuring mode then the Red lead is Positive. In some older models the Black lead may be positive"

Sorry for any confusion

Had the exactly same problem. Strangely, changing fuel filter worked for me.

I explained all of the above to my Italian mechanic, and like Mikadiver he suggested replacing the fuel filter. He did so, and in spite of it being Springtime here in SA, we have had 32degC already, and I spent most of midday in traffic and the car kept going when before it would have cut out. I'm holding thumbs, but it looks as though it's cured!

No, it hasn't been cured. On Tuesday after a two-hour trip out of Johannesburg, I got stuck in traffic back in Johannesburg and it failed again! I have booked it in to have the Crank sensor removed and heat-stress tested. If it fails under the test I will replace it.

It might be cheaper to just change it instead.

The RPM sensor (is this what others call the crank sensor?) was taken out and bench tested yesterday, and heated to near melting point but with no failure evident. Some refer to a MAF or MAFF. Would that be the air mass sensor? Perhaps I'll do that next. (What does MAF stand for?)

I am at my wits end to try to find this fault, and as mentioned above although Fiat agents here have all the diagnostic equipment, they did not import Barchettas and consequently do not have the diagnostic programme for them. Maybe I'll have to live with this, but it means I can never go on a long trip with the car.:bang:

Interested as to how he tested it on the bench, did he simulate the castellations passing by, and how did he test the output?

Next time it stops, try taking the fuel filler cap off and refitting, then try to restart.

All I can say is that anyone with access to a dealership with a good mechanic and with the relevant software can count him(her)self very fortunate. We here in South Africa have computer diagnostics for EVERY make of car except for mine. I have the only Barchetta in South Africa, and no diagnostic software was imported for it. I am tearing my hair out

I'd be tempted to fit a new crank sensor and see what happens.