bertypunto
New member
- Joined
- Jan 10, 2010
- Messages
- 17
- Points
- 6
Hi Guys ,
I've been experiencing hot starting issues with my 2009 Fiat Grande Punto 1.3 Diesel Multijet ( owned from new) for around three years , hopefully I'm now close to resolving the root cause. I thought I would share my experiences for the benefit of those that have the same symptom , hopefully to save them time , money and heartache in future.
The problem started one summer when I stopped the car to go and get some shopping after a long run back from work ( about an hour on the motorway). When I tried to restart the car after 15 minutes in the shop , the engine turned over at normal cranking speed but just wouldn't catch. I tried switching on and off the ignition a number of times over the course of about 5 minutes before the engine finally started. Once running , the engine drove without issue and there were no engine managment lights or problems with performance. The probnlem seemed to occur on a number of occasions , always when the engine was hot after a medium or long run and the car had been standing for a few minutes with the engine switched off.
As winter came , the problem seemed to get less prolific and the engine would start either hot or cold without much of an issue , though generally taking longer when hot. Cold starting was never an issue and generally the car ran well with no undue smoke or uneven idle when hot or cold . The average fiuel consumption even peaked around 60 - 65 on a long run. The car had around 60 k miles at the time , so I put it down to the engine getting tired and maybe a little less compression or worn / gummed injectors.
The following year the problem returned again in summer months and seemed to get worse , taking longer and longer to start when hot and being present after shorter periods of the engine being stopped.
I had fitted one of those diesel " fuel performance boxes" that sits in series with the fuel pressure sensor in the common rail system , which I initally thought was the culprit. I unplugged the unit and seemed to get a slight improvment in the issue though it never went away. As a result of unplugging and plugging back in the fuel sensor I stumbled across a way of being able to start the car when it was most stubborn , by leaving the sensor unplugged. The engine would start but it feathered into life rather than starting cleanly and resulted in an ECU / engine mgt light on the dash and cap in performance / revs at around 3000 rpm. When the sensor was plugged in again with engine stopped and left overnight the car would start normally and fault light would clear iteslf.
One one occasion it got to the point where the battery became completely drained from trying to restart and in need of a replacment as a result. In an attempt to fix the issue I not only bought a higher capacity battery ( higher cranking amps and Ampere Hours) but also started to look on the web for possible causes. The battery seemed to give a slight improvement in that the car would eventuially start when hot , but the issue was still there.
In an attempt to solve the root cause than the symptom I started a series of replacments based on web research and advice from mechanics.
First up I changed the crank sensor - I didn't test it before replacement , but its location next to the turbo made it a high suspect for heat damage and its a 10 minute job with the car on ramps.
No change
Next I changed the Camshaft position sensor - Again this was a blind change with no test . simple to cahnge takes about 10 minutes ( when you realise the airbox can disconnect by pulling the pipes off at the MAF and inlet pipe and then jiggle out from the holding pegs).
No Change
Next I changed the Manifold Air Pressure sensor ( MAP) - this was well sooted up
No Change
At this point I invested in multiecuscan software as the cheap hand held device i'd been using never showed any fault codes or logs when the fault was present.
This showed a few potential faults one of which was the throttle pedal position being implausable
I changed the throttle pedal
No change
Considering the fact the car would start with the fuel rail pressure sensor unplugged, and the multiecuscan software did show fault logs on low fuel pressure , next I replaced this.
No Change
Realising the fuel rail pressure is controlled by the fuel rail pressure regulator ( on the other end of the fuel rail) I changed this
No Change
Whilst trying to diagnose the fault with the software and engine running I noticed the radiator fan didnt seem to be coming on and the coolant pipes either side of the thermostat seemed at different temperatures. I changed the thermostat and coolant temperature sensor as one unit.
No Change
Now at this point I was seriously thinking about moving to an area prone to flooding or high car crime to rid myself of the car and the problem, but decided to soldier on and not let it beat me.
Looking at the diagnostics from the software I could see the battery voltage spiking during cranking and that the fuel pressure never seemed to reach its desired set point when the starting problem was present. The battery voltage appeared to indicate 11.9V and a battery tester suggested it was still healthy. I tried a number of scenarios with the engine coolant temperature and fuel pressure at varying temperatures , there seemed no correlation.
With the battery draining I jumped the battery from another car and found that the additional capacity would allow the engine to start , but after 10 to 15 seconds of cranking. Though this allowed the car to start , it wasn't a permanent solution to either carry another battery or a set of jump leads on a sunny day.
Then I came across a thread on the Vauxhall foruim ( having realised the corsa is cursed with the same engine) that suggested diesel injector let by could be the cause.
Up to this this point I had spent some money on parts ( but fitting them myself) i was a little concerned about changing injectors without some confirmation they were faulty , especially at over 180 pounds a pop , or 350 each from Fiat.
I bought a leakage detector kit and tested the four injectors for return fuel and found injectors 2 and 4 were delivering different amounts to each other and significantly more more than 1 and 3 , which were about the same.
I contacted a diesel injector refurbishment company who could supply reconditioned warranteed units at 100 pounds each and ordered two new units along with a slide hammer removal kit for the injectors.
The theory is this :
If the injectors have let by , the pressure in the fuel rail struggles to reach setpoint , particualrly as the priming pressure is set by the speed at which the fuel pump is turning , based on the drive from the crank. When the engine is hot , the pump clearances are bigger and the fuel is thinner so the leakage creates a bigger pressure loss and the pump struggles more to overcome it. If you don't have enough pressure the fuel doesn't atomise properly and the engine won't start. Therefore a good battery can allow just enough power and cranking speed to overcome the loss in pressure from a leaking injector. Once the engine is running , the engine speed and fuel pump speed /pressure is sufficiently high enough to overcome the let by in the injector.
I hope that this weekend I will change the two faulty injectors and the problem will be solved.
The learnings from this episode are :
Buy youself the multiecuscan software and cables if you ever plan to work on your Fiat/ Alfa yourself. For 100 pounds its money well spent and allows you to diagnose , clear faults and even enable functions . It's also required if you want to change injectors as you need to imput the injector characteristic in the ECU.
If you have a hot or cold start issue , test the sensor in the fault state if you can , before you change it. There are you tube videos for most of them with the correct values.
If you think you have a fuel issue like me , the e bay injector leak kit is money well spent at 30 quid.
Never give up !
I've been experiencing hot starting issues with my 2009 Fiat Grande Punto 1.3 Diesel Multijet ( owned from new) for around three years , hopefully I'm now close to resolving the root cause. I thought I would share my experiences for the benefit of those that have the same symptom , hopefully to save them time , money and heartache in future.
The problem started one summer when I stopped the car to go and get some shopping after a long run back from work ( about an hour on the motorway). When I tried to restart the car after 15 minutes in the shop , the engine turned over at normal cranking speed but just wouldn't catch. I tried switching on and off the ignition a number of times over the course of about 5 minutes before the engine finally started. Once running , the engine drove without issue and there were no engine managment lights or problems with performance. The probnlem seemed to occur on a number of occasions , always when the engine was hot after a medium or long run and the car had been standing for a few minutes with the engine switched off.
As winter came , the problem seemed to get less prolific and the engine would start either hot or cold without much of an issue , though generally taking longer when hot. Cold starting was never an issue and generally the car ran well with no undue smoke or uneven idle when hot or cold . The average fiuel consumption even peaked around 60 - 65 on a long run. The car had around 60 k miles at the time , so I put it down to the engine getting tired and maybe a little less compression or worn / gummed injectors.
The following year the problem returned again in summer months and seemed to get worse , taking longer and longer to start when hot and being present after shorter periods of the engine being stopped.
I had fitted one of those diesel " fuel performance boxes" that sits in series with the fuel pressure sensor in the common rail system , which I initally thought was the culprit. I unplugged the unit and seemed to get a slight improvment in the issue though it never went away. As a result of unplugging and plugging back in the fuel sensor I stumbled across a way of being able to start the car when it was most stubborn , by leaving the sensor unplugged. The engine would start but it feathered into life rather than starting cleanly and resulted in an ECU / engine mgt light on the dash and cap in performance / revs at around 3000 rpm. When the sensor was plugged in again with engine stopped and left overnight the car would start normally and fault light would clear iteslf.
One one occasion it got to the point where the battery became completely drained from trying to restart and in need of a replacment as a result. In an attempt to fix the issue I not only bought a higher capacity battery ( higher cranking amps and Ampere Hours) but also started to look on the web for possible causes. The battery seemed to give a slight improvement in that the car would eventuially start when hot , but the issue was still there.
In an attempt to solve the root cause than the symptom I started a series of replacments based on web research and advice from mechanics.
First up I changed the crank sensor - I didn't test it before replacement , but its location next to the turbo made it a high suspect for heat damage and its a 10 minute job with the car on ramps.
No change
Next I changed the Camshaft position sensor - Again this was a blind change with no test . simple to cahnge takes about 10 minutes ( when you realise the airbox can disconnect by pulling the pipes off at the MAF and inlet pipe and then jiggle out from the holding pegs).
No Change
Next I changed the Manifold Air Pressure sensor ( MAP) - this was well sooted up
No Change
At this point I invested in multiecuscan software as the cheap hand held device i'd been using never showed any fault codes or logs when the fault was present.
This showed a few potential faults one of which was the throttle pedal position being implausable
I changed the throttle pedal
No change
Considering the fact the car would start with the fuel rail pressure sensor unplugged, and the multiecuscan software did show fault logs on low fuel pressure , next I replaced this.
No Change
Realising the fuel rail pressure is controlled by the fuel rail pressure regulator ( on the other end of the fuel rail) I changed this
No Change
Whilst trying to diagnose the fault with the software and engine running I noticed the radiator fan didnt seem to be coming on and the coolant pipes either side of the thermostat seemed at different temperatures. I changed the thermostat and coolant temperature sensor as one unit.
No Change
Now at this point I was seriously thinking about moving to an area prone to flooding or high car crime to rid myself of the car and the problem, but decided to soldier on and not let it beat me.
Looking at the diagnostics from the software I could see the battery voltage spiking during cranking and that the fuel pressure never seemed to reach its desired set point when the starting problem was present. The battery voltage appeared to indicate 11.9V and a battery tester suggested it was still healthy. I tried a number of scenarios with the engine coolant temperature and fuel pressure at varying temperatures , there seemed no correlation.
With the battery draining I jumped the battery from another car and found that the additional capacity would allow the engine to start , but after 10 to 15 seconds of cranking. Though this allowed the car to start , it wasn't a permanent solution to either carry another battery or a set of jump leads on a sunny day.
Then I came across a thread on the Vauxhall foruim ( having realised the corsa is cursed with the same engine) that suggested diesel injector let by could be the cause.
Up to this this point I had spent some money on parts ( but fitting them myself) i was a little concerned about changing injectors without some confirmation they were faulty , especially at over 180 pounds a pop , or 350 each from Fiat.
I bought a leakage detector kit and tested the four injectors for return fuel and found injectors 2 and 4 were delivering different amounts to each other and significantly more more than 1 and 3 , which were about the same.
I contacted a diesel injector refurbishment company who could supply reconditioned warranteed units at 100 pounds each and ordered two new units along with a slide hammer removal kit for the injectors.
The theory is this :
If the injectors have let by , the pressure in the fuel rail struggles to reach setpoint , particualrly as the priming pressure is set by the speed at which the fuel pump is turning , based on the drive from the crank. When the engine is hot , the pump clearances are bigger and the fuel is thinner so the leakage creates a bigger pressure loss and the pump struggles more to overcome it. If you don't have enough pressure the fuel doesn't atomise properly and the engine won't start. Therefore a good battery can allow just enough power and cranking speed to overcome the loss in pressure from a leaking injector. Once the engine is running , the engine speed and fuel pump speed /pressure is sufficiently high enough to overcome the let by in the injector.
I hope that this weekend I will change the two faulty injectors and the problem will be solved.
The learnings from this episode are :
Buy youself the multiecuscan software and cables if you ever plan to work on your Fiat/ Alfa yourself. For 100 pounds its money well spent and allows you to diagnose , clear faults and even enable functions . It's also required if you want to change injectors as you need to imput the injector characteristic in the ECU.
If you have a hot or cold start issue , test the sensor in the fault state if you can , before you change it. There are you tube videos for most of them with the correct values.
If you think you have a fuel issue like me , the e bay injector leak kit is money well spent at 30 quid.
Never give up !