Technical Fiat Grande Punto 1.2 2006

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Technical Fiat Grande Punto 1.2 2006

Spanner109

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Hi All:)

My daughters (82k miles) 2006 Grande Punto 1.2 is driving me mad.
The car runs like a Swiss watch it starts on the button you can take it out for a drive (30 + Miles) and it is faultless until you go to slow down for a junction or park and the revs drop to just above idle the the engine just stops dead there is no juddering, the engine just stops dead, some times the engine will start straight back up and other it will take a little throttle action. After it has cut out you can leave the car running while parked up and it will run for a while and then just stop, it can run for 15 min or less before it stops.

There are no engine fault codes showing when I scan with multiEUscan.
Parts that have been replaced in the great fault hunt so far:
Coil pack, leads and plugs
Crank shaft sensor
Throttle body
Map Sensor
Vacuum hoses checked and are ok
all earthing points cleaned

After replacing each of the items above the car always gave the same symptom/fault. with no stored error codes.

My next may be the fuel pump... meh!

Any help or pointers would be greatly appreciated.
 
Have you used multimeter to measure resistance between negative terminal and earthing points and the engine block, the alternator and the gearbox? It should always give very low resistance when earth is good. Also you've cleaned the battery terminals and checked the condition of the battery. I've heard that bad battery or corroded terminals can cause crazy symptoms like some sensor values being unavailable to the ECU.

Has the timing belt been changed on schedule? Check the long term fuel trim and short term fuel trim values from multiecuscan. Any value negative or positive means that the ecu is compensating fuel injection, either decreasing or increasing to get correct fuel mixture. The value on a hot engine should be close to zero, any value lower/higher than +-20 could indicate a possible problem with the fuel delivery. Also if you're using cheap chinese elm327 obd2 reader, you can't trust all the parameters and they're usually unable to connect to canbus. However fault codes can be read and erased.


Also check the fuel pressure on idle from the fuel rail.Multiecuscan is also able to tell the values for the injectors and lambdas.


The symptom you're describing sounds like a worn fuel pump acting up. Also a partially blocked fuel filter could play a part in this . It's usually a part of the fuel pump assembly itself, so the remedy is to change the whole fuel pump i'm afraid. You've already changed too many parts though. :confused: I'm not sure if anyone has changed the filter element itself.


When there's no fault codes present, the ecu thinks the engine's running OK. Also fuel injectors could be the issue. Of course the engine itself could be worn if it can't idle properly. Have the engine compression tested before changing any more parts.
 
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This is just a tip - coolant gauge shows ok temperature before shutting down engine?
 
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Hi eeeno & Rado77

Thank you for both replies, it is appreciated. :D
@ Rado77 engine temp before shut down is fine
@ eeeno Earths are good, my obd2 reader is not a cheap version ;) and I see just as much info if not more than I do when I hook up the snap-on diag. I take your view also that this is looking like a possible fuel pump issue, we shall see.
I shall report back after further investigation. (y)
 
Hi mates,
I hope Spanner109 solved already the problem. Anyway, some thoughts about:
I am struggling for 2.5 years with a punto mk2 1.2, 60 hp from 2003. Not yet solved, but I came to know a bit the little italian...
- I dare to suggest that the filter of the fuel pomp for the grande punto could be cleared, if it is similarly to little punto 1.2. Done it for mine.
- You can also check the pressure with a gauge at the fuel rail.
- I sustain the point of eeeno about the TDC after timing belt changing (the matter fact all his suggestions, but especially this one), since I think is one of the faults without an error code
- 30 miles or 15 minutes are more or less the time for engine to arrive at operating temp. Anything related to temperature should be check, included the resistor of the interior fan switch.
- not sure if the relee of the pomp could be worn that way, but give it a shut and deserve a check
- not sure if the cut-off switch could play that hard, but it deserve a check
- the distance of crankshaft sensor from the wheel should be checked also, according to the manual. And, i just realised that after changing it, there is a calibration to be done: phonic wheel learning reset.
- also, the throttle body needs a re-calibration, as I know, because ECU is smart but not enough...
- least, not last: any electric not so bothering issue, could infect some ECU signals. An injection diagram could confirm such a coincidence.
Sory for the long post from a non-native in English.
Good luck!

L.E. I would check also if the battery is well anchored and does not touch any other cables.
 
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