Technical 1.3 Diesel Multijet Hot Starting Issue

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Technical 1.3 Diesel Multijet Hot Starting Issue

bertypunto

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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 !
 
Know your pain. My last car wouldn't start when cold, had sensors changed. All electrics checked, battery replaced, camshaft sensor changed and was the egr valve that was stuck open. In trying find the problem the injectors seals worn down so had be replaced as well (no compression). Took 6 months back an forth from different garages including dealer before got it fixed
 
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Be careful while removing them. Heard some scary stories about stuck broken injectors :/
 
@bertypunto props for not giving up berty. Also props for the logical write up.

Generally speaking these engines are well regarded and generally speaking are considered reliable, notwithstanding Vauxhall and Fiat's stupid 18K oil change service intervals which are contributing to early engine and chain failures.


Those who think manufacturers word is gospel better think again. Commercial pressure for profit and the perception from the market of a well engineered vehicle has made manufacturers make claims such as "For the life of the car" (BMW gearbox oil changing service interval statement), all with the aim to have customers and lease companies buy their vehicles as perceived to be less problematic than others. The OEM's couldn't give a **** if the car blows up as soon as the 3 year warranty is out as they expect the owner to come in and buy a new replacement whilst the part-ex goes to the second hand/trade market to be sold on to buyers some of which become the unlucky statistics. I appreciate OP that this doesn't apply in your case, but it does from the point of view of the age of the car and the mileage beyond the 3 year period which moves you from the New bracket to the second hand bracket.


I am also an owner of a 1.3 mjet, purchased as the third owner when the car was 7 years old and despite needing quite a bit of TLC and a major service due to the second owner abusing the car for a period of 2 years, its has been a peach thus far (coming up to 2 years of ownership).


My understanding of modern diesel engines is that they are all susceptible in this regard due to the nature of the very high pressure fuel rail systems they employ. The more efficiencies the OEM's are made to chase the more complex the system become and the tighter the tolerances required to achieve this, thus components and seals are now expected to deliver performance increases by a number of factors higher than previous generations. You should read some stories about modern Ford's e.g. Mondeo's and Focus's with similar injector issues and ECU's loosing the Injector codes and thus not starting the cars........


I recently read an article on a ford forum where the car's injectors which are programmed into the ECU due to small differences in the flow tolerances between injectors having to be further mitigated by the ECU to ensure the engine will get the correct amount of fuel into each cylinder, being lost/deleted from the ECU and thus the ECU having to be re-programed again with the lost injector codes. In an event of an injector change the same process has to be implemented for each injector. Gone are the days of just being able to drop in an injector of the same type/brand/cc and off you go and goes to show how tight the engine performance characteristics are nowadays, particularly in diesel engines.


Personally I think what's lacking most these days are the skills required by the mechanics to work through and correctly diagnose a fault. Everyone now reads codes from a reader/laptop but beyond having a specific item being identified by the software tools they are lost.


Keep up the good work as you are more likely to work the problem out (with some help here and there) than paying someone else to do it for you and keep us posted.


If there is anything I can dot o help, shout.


regards, Humour.
 
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I can agree with you humor everything is diagnostic based now (which isn't always correct). I had a ford focus 1.8 diesel and the injectors where coded as you said. I think fiats are the same. Problem is they want you to go to them to get things done hence why they code them so costs you a pretty penny to get them re programmed etc. Its like getting a car serviced now or clutch changed you need a dealers computer (or capable software). Just to do basic things so the cars ecu knows they've been done. Gone are the days you just replaced a clutch and to reset service you pressed a few buttons inside the car. I admire the op in keep going no matter how hard it seemed. Its to easy to give in, especially with cars that are being problematic and cant find the fault.
 
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The refurbished injectors have arrived complete with new coding values for the ECU. The multiecuscan software allows for these codes to be input by the DIY enthusiast , so with the other tooling I've bought ( injector removal slide hammer kit , copper washer removal tool , and re seating tool ) I should be good to go.

Fingers crossed this fixes the issue as its gone from being inconvenient to a real headache , refuelling has to be done first thing before I've travelled any distance , otherwise i'm stranded at the petrol station.

Interestingly the ECU never seems to log a fault when the car is difficult to start , only after its displayed an Engine management fault while running or if I've disconnected the pressure sensor to get the car to start. It's almost as if the logging doesn't become active until the engine has started. That's why its been so frustrating and difficult to pinpoint the cause.

Thanks for the support , encouragement and tips from those that took the time to post.
 
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Interestingly the ECU never seems to log a fault when the car is difficult to start , only after its displayed an Engine management fault while running or if I've disconnected the pressure sensor to get the car to start. It's almost as if the logging doesn't become active until the engine has started. That's why its been so frustrating and difficult to pinpoint the cause.


Sounds like you are as well prepared for the task as it is possible to be as a DIY'er. I too hope this is the root cause that once addressed will allow you to enjoy and rely on your GP. Good luck and keep us posted.


With regards to the faults throwing up, the ECU can only sense faults pertaining to sensors connected to it which carry electric current and resistance which can be measured if in or out of tolearance.


Mechanical problems unfortunately as it is probably the case of O-ring or seals leaking and not allowing the rail to hold pressure will not be detected or reported by the ECU for obvious reasons. The ECU may or may not however have the means to sense if the injectors a throwing up different resistance values, which I suspect leaking O-rings should have no ability to affect in that way, as the ECU cannot directly measure the flow rate of an injector (hence the necessity for ECU to Injector "calibration/mapping" when injectors are being replaced), but I'm no expert in that area.


Humour
 
Fitted new injectors to No2 and No4 cylinders and coded the new injector values into the ecu. Not as difficult a task as you might expect , however the first step is that the top of the injector needs to be removed so the slide hammer extractor can be fitted.

The alignment that fiat use for the plug connector and the hex head that holds the top cover on the injector are of course mis aligned so you cannot use the side slotted socket designed to remove the injector cover. As a result I had to resort to using a large adjustable spanner.

When you remove the cover there is a tiny spacer and spring that are released, care is required to ensure these don`t escape and become lost.

Of course , the fuel rail connectors, camshaft position sensor and the injector connectors all need to be released along with the two bolts that secure the fuel rail to the cam cover , before the two cap heads that hold the four injectors in place.

Unfortunately the injectors are held in place in pairs so 1 and 2 , 3 and 4 need to be released in pairs.

With the injectors removed I fitted a thin plastic tube to a vacuum cleaner and hoovered out the cavities in which hte injectors sit, these were full of debris so it was a job worth doing before refitting.

I put it all back together with new injectors and then recoded the new injectors to the ECU , the car started after a short time to reprime the system.

Sadly after all this work the hot start problem still persists.

So I need some help / comparison with a working 1.3JTD engine from someone that has the multiecuscan or similar software.

Below ive listed the cranking speed and fuel rail pressure that i am getting along with the status of the car ( hot or cold)

From what I can see , the ECU is calling for 300 bar fuel pressure on starting , however the pressure my car is achieving ranges between 140 and 180 bar when it manages to start and is lower when it doesn`t.

What would be great is to see a car without the hot start problem and what pressure it achieves on starting before the engine catches when both hot and cold.

cranking RPM FUEL PRESS COMMENT
194 180 bar starts first thing in morning
282 148 bar starts with jumped battery and hot engine
260 142 bar won`t start with hot engine


Im now turning my attention to the fuel pump......
 
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That's unfortunate Berty and its turning out to be a jobs worth no doubt.


I don't have the multiscanecu so I can help in that regard, unless I bring the car to you. Where abouts in the country are you?


Humour
 
That's a generous offer humour. I'm near Luton. I plan to look at the fuel lines and the filter tomorrow and maybe change the battery as it now getting hammered.
 
Bertypunto, if you still need some help on Tuesday and Humour lives anywhere near merseyside i maybe able help. I've got multiecuscan so can use that if he likes to help figure what it is at turn over. I do have access to a 1.3 multijet but it's in a 500l (2013). Now in theory its the same engine so should be the same pressure to turn it over. I maybe do a pressure test with multiecu on that if needed.

The only thing that seems odd to me is when your car is jump started it starts fine (when hot). If it's not it doesn't (also when hot). This sounds more like a electrical fault than a pump to me. Before getting a new pump check the electrics around the pump itself and also when the car is warm check the fuel line(s) that come from the pump to make sure everything is fine. Also has you've stated check the fuel filter. Best thing would be to reseat the fuel filter to make sure there isn't any air getting into the system.
 
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Hi Cobalt. Thanks for offering you help. I have changed and purged the fuel filter this morning and also run another injector leak test. Whilst poking around under the bonnet I noticed the fuel pump also has a return leg back to the tank. I suspect the return leg from the pump may be an overpressure relief valve. If this was letting by , that could explain the issues I'm getting.

It seems strange that I am never able to get the desired fuel pressure on hot cranking , even with the additional jump of power from another car the fuel pressure never rises above 200 bar even with a set point of 308. Once the engine starts the pressure can be achieved and set point and actual values follow each other as expected.

The other thing I see is the fuel system seems to have some form of recirculation back to the fuel filter and inlet. This could explain high temp starting and thinner fuel being an issue on a worn pump.

I would be grateful to you cobalt if you could look to see what the desired and actual values were for the 500 1.3 :worship:. I found using the graph function helped establish the max value and corresponding crank or engine speed before the engine catches.


New pump is about 180 pounds , if this dent fix it I don't know for the moment where to go next. Certainly a brain teaser this one.!
 
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No problem, which graph do you need me look at but be Tuesday before get chance look at it warm.

It could be pump like you said but id be more inclined on it being a pipe/sensor or maybe fuel filter at pump end (if they have one).

If you can get safe access to the pipes on start up warm try squeezing the pipes (without jump starting). This will then let you know if a line is bad due to blockage or something.

Just seen your original post again. You stated that your getting 11.9v. Should get at least 12.5v. Can you not get a spare battery to test car when warm? Also check the alternator current (should be 14.5v or so). An also try testing starter
 
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The battery voltage is a weird one . I just fitted a brand new battery and still not getting over 12v at rest, it's actually around 11.7 v and 13 with the engine running. All my diagnostic kit suggests the alternator and battery are ok, so this may be an odd earth fault. I've cleaned and copper ease lubed all the earn points I can find but not got any better results. If you could graph the desired fuel pressure and actual fuel pressure alongside the engine speed it would be good to know if the 300 bar is ever achieved during cranking before the engine starts.
 
The battery voltage is a weird one . I just fitted a brand new battery and still not getting over 12v at rest, it's actually around 11.7 v and 13 with the engine running. All my diagnostic kit suggests the alternator and battery are ok, so this may be an odd earth fault. I've cleaned and copper ease lubed all the earn points I can find but not got any better results. If you could graph the desired fuel pressure and actual fuel pressure alongside the engine speed it would be good to know if the 300 bar is ever achieved during cranking before the engine starts.

how are you getting this @12V figure, :confused:
from battery terminals,
of from a device / fuseboard..??

IF it's low on power you'll struggle to get a decent rail pressure = becuase of lower cranking speeds,
Charlie
 
The voltage is from multiecuscan which is measured at the ecu. The actual battery voltage seems ok when measured independently. I don't think this is a battery issue as a brand new battery gives the same issue and the cranking speed is actually higher when hot than cold when I am getting a lower rail pressure. It's worth noting that even with a jumped battery the car struggles to start it just takes a much longer time than when cold.

IMHO the desired fuel pressure should be achievable at similar crank speed be it hot or cold. I don't seem to get the same pressure for the same or higher cranking speed when hot. In either case the set point never seems to be achieved unless the engine is turning over at 800 rpm , it's never achieved at cranking speeds of 200-300 rpm. This doesn't make sense as the fuel rail is designed to modulate over pressure so the pump should deliver more than 300 bar when cranking. This is why I would like to compare with another 1.3 multijet , what it cranks at and what pressure is achieved.
 
That's a generous offer humour. I'm near Luton. I plan to look at the fuel lines and the filter tomorrow and maybe change the battery as it now getting hammered.


SNAP! :D


I'm in Luton too fella. Check your PM for my number. Call me and I'll pop over with my GP whenever it suits outside office hours.


Humour
 
The voltage is from multiecuscan which is measured at the ecu. The actual battery voltage seems ok when measured independently. I don't think this is a battery issue as a brand new battery gives the same issue and the cranking speed is actually higher when hot than cold when I am getting a lower rail pressure. It's worth noting that even with a jumped battery the car struggles to start it just takes a much longer time than when cold.

IMHO the desired fuel pressure should be achievable at similar crank speed be it hot or cold. I don't seem to get the same pressure for the same or higher cranking speed when hot. In either case the set point never seems to be achieved unless the engine is turning over at 800 rpm , it's never achieved at cranking speeds of 200-300 rpm. This doesn't make sense as the fuel rail is designed to modulate over pressure so the pump should deliver more than 300 bar when cranking. This is why I would like to compare with another 1.3 multijet , what it cranks at and what pressure is achieved.

have you replaced the main battery to EARTH cable?, they are sometimes badly corroded internally:bang:
 
I have seen some reports of hot starting problems due to corroded earth cables on other forums. They seem to have the symptoms of slow turn over and cranking rather than pressure issues. I don't appear to have slower cranking speeds when the car is hot , so I haven't considered replacing the cable up to this point. Definitely something to consider if the current avenue doesn't turn up any improvement.
 
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