Technical 169 Multijet Intermittent Hard Starting

[Cook1e]

Hi Chaps,
2009 Multijet (Dynamic, I think) about 85K miles, serviced about 1,000 miles ago. I've had the car over 4 years and it's always started after a couple of turns.
Recently (not coincident with anything I have noticed) the car has been difficult to start sometimes, needing 2, 3 or even 4 attempted starts. Sometimes when hot, but usually when cold. Over half the time, it starts fine.
I noticed once that it caught just as I let off the starter - if it were a petrol engine, I might have thought low battery not having enough voltage for the ignition when the starter is engaged, although it turns over perfectly healthy, no sign of a weak battery.
I've just given it a dose of injector cleaner, but I don't know what else to look at.
Any thoughts from the Panda Massive?

EDIT: No codes showing and the car drives perfectly.

 

[g8rpi]

Check the battery earth lead for bad connections and internal corrosion. Try two jump leads one from battery negtive to chassis and one from negative to engine block.

 

[koalar]

Check the battery earth lead for bad connections and internal corrosion. Try two jump leads one from battery negtive to chassis and one from negative to engine block.

Not sure I get this

turns over perfectly healthy, no sign of a weak battery.

If it turning over fine, it can carry a good few amps

but usually when cold.

I'd start looking around fuel pumps and glow plugs, might have to think about how we can diagnose this,

 

[varesecrazy]

Are you letting the tank pump run to supply under the bonnet?

Not everybody does.. And it can become a problem as things wear

 

[g8rpi]

A bad battery negative lead can allow reasonable cranking with a good battery but still produce enough voltage difference beween the chassis (reference for ECU) and engine (reference for many sensors) to cause issues.

 

[Cook1e]

Are you letting the tank pump run to supply under the bonnet?

Not everybody does.. And it can become a problem as things wear

Explain this another way please? Do you mean let the pump run for a few seconds before hitting the starter? I think I have been doing this, but nothing has changed in the way I start the car.

 

[Cook1e]

A bad battery negative lead can allow reasonable cranking with a good battery but still produce enough voltage difference beween the chassis (reference for ECU) and engine (reference for many sensors) to cause issues.

Good suggestion, I'll get the meter on it tomorrow

 

[Cook1e]

Not sure I get this

If it turning over fine, it can carry a good few amps




I'd start looking around fuel pumps and glow plugs, might have to think about how we can diagnose this,

Glow plugs were replaced a couple of years ago. What are you thinking re fuel pump?

 

[koalar]

Glow plugs were replaced a couple of years ago. What are you thinking re fuel pump?

They need very high pressure to spray properly

As the seals start to fail it gets harder to start

Measure the pressure and look for leaks is a good start

Here's fiat take on hard starting for you engine

Click link underneath

Home Page

aftersales.fiat.com

 

[The Panda Nut]

If a diesel has a good strong starter and spins fast enough and has fuel at the injectors it will go. If its not starting and this is when cold I would immediately suspect glow plugs. These are expendables and a replacement set may not have been as good the originals. The indicators or poor glow plugs would besmoke on start up. probably the grey unburnt fuel type.

Air ingress into the fuel system also a big cause of bad running and starting. I would try and disconnect the fuel line from tank to pump and check you have a good fuel flow. Check all the pipes and lines for tightness and leaks, Check the fuel cap vent is not blocked. Then check the glow plugs test to ensure they are not blown. You could have 1 or more not working as well as they should. I would anticipate this is where the problem is. If its not one of these things then have the injectors checked for spray pattern and new seals fitted. This is not a big job at a diesel centre.

If this doesnt work then a compression check may be required to ensure you dont have a bad valve but 85K is nothing to a well maintained diesel. I reckon it takes 50 to 60K to see the best out of a diesel engine and then they just keep improving.

If you ask at a diesel centre they will be able to test the fuel pump and overhaul if necessary, but I doubt this will be required if its never been run on petrol or run dry.I have covered a huge milage on diesel and never had a pump issue. There are valves and springs internally that can fail though.

I hope this very general list may give an idea or two.

 

[koalar]

Good suggestion, I'll get the meter on it tomorrow

Got a meter, great, on volts put one lead on the engine block and the on the battery negative post

Crank the engine

Should stay below 0.5V

Heres a faulty earth

Here you can see the bock go slightly positive (test light dim) when the ignition is switched on and battery voltage (test light bright) as you try and crank


But the same test can be done with a multi meter

 

[koalar]

You need good crank speed for nice injector sprayl

Crank speed can be deceptive as the battery deteriorates slowly


You can directly read the Crank and voltage with one of these

Which allows you to plot crank speed

Which is a petrol car and low battery

And plot the voltage drop while cranking

Which here you can see fall badly and very quickly


But sometimes it's just easier to swap the battery or start with an extra battery connected with jump leads

How to jump start a car in 9 steps | The AA

How to jump start a car step by step guide. Learn how to safely jump start a dead battery by using another car or a battery booster pack.

www.theaa.com

Check on the right hand side of the engine for what looks like oil leek


Don't assume the newish glow plugs are working, especially if bought online

 

[Cook1e]

Thanks guys, I'll get the pump pressures checked and report back

 

[irc]

Don't overlook the Positive battery lead.
I find it is worth cleaning all Positive and Negative connections from battery through to starter motor before getting into more complicated (and expensive) work.
The Multijet is quite picky about cranking speed. It doesn't take much of a reduction to fail to start, and a combination of slightly poor connections can be enough to make a difference.
Cleaning up both terminals on the starter is worthwhile if you're in the area - the shorter one can become quite crusty and still usually work, but definitely works better when clean (and coated in dielectric grease)

 

[Cook1e]

Connected to MultiECUScan this morning with a view to looking at battery voltage and fuel pressure.

She started first turn, after less than a second or so of glowplug light. Typical! I thought - no problems now I'm looking for them

I spent a few minutes setting up the computer to graph battery voltage and fuel pressure and tried again. No start. At least I'm on my own drive...

Fuel pressure looked OK and battery voltage stayed above 10.5 volts whilst cranking, but no start. I tried a few more times, probably cranking for a total of around 30 seconds. The cranking speed was noticeably slower by then, so I've put the battery on charge.

Then I remembered something...
I had connected MultiECUScan a few weeks ago to diagnose the engine light, which turned out to be a sticking wastegate. When I'd done, I tried to start it again to ensure the fault had cleared - it would crank, but not start. This was the first time the problem had occurred. I wondered what the hell I had done and disconnected the OBD device, after which she started fine. I thought no more of it until just now...

... coincidence, surely?

Back again when the battery's charged.

 

[The Panda Nut]

Mmmm Sounds like this might be connected. OBD shouldnt affect starting at all but the wastegate sticking could maybe affect a sensor or two? I had a Golf which was great until without warning it webt into limp home and it turned out had a sticking variable vane turbo. SO while I dont know what its apparent that turbo issues can appear out of nowhere. I dont know if a boost pressure sensor might have an effect on starting if the reading was spurious.

 

[Cook1e]

Mmmm Sounds like this might be connected. OBD shouldnt affect starting at all but the wastegate sticking could maybe affect a sensor or two? I had a Golf which was great until without warning it webt into limp home and it turned out had a sticking variable vane turbo. SO while I dont know what its apparent that turbo issues can appear out of nowhere. I dont know if a boost pressure sensor might have an effect on starting if the reading was spurious.

Thanks for the tip, but I've had the wastegate stick before. Happens when I forget to thrash the engine from time to time Simply a boost pressure code, 5 minutes with a can of WD-40 and a big screwdriver, then clear the code. No problem.

I can't imagine how connecting an OBD module to the socket could affect starting, but that was the first time I saw the starting problem

 

[koalar]

Great we already can rule out quite a bit

Connected to MultiECUScan this morning with a view to looking at battery voltage and fuel pressure.

She started first turn, after less than a second or so of glowplug light. Typical! I thought - no problems now I'm looking for them

Bad earth or positive is unlikely

I spent a few minutes setting up the computer to graph battery voltage and fuel pressure and tried again. No start. At least I'm on my own drive...

Great it fail straight after on a restart, glow plug not needed especially this weather, so unlikely

Fuel pressure looked OK

Over 300 bar? I take it

and battery voltage stayed above 10.5 volts whilst cranking, but no start.

Dam symptoms were pointing to a battery drop off which would have been simple

I tried a few more times, probably cranking for a total of around 30 seconds. The cranking speed was noticeably slower by then, so I've put the battery on charge.

Once the cranking slows it will not start, this is normal behaviour, but it's a chicken and egg

Long crank depleted battery

Or can't start due to too slow a crank

If you have a second car swap the batteries over might be possible

Then I remembered something...
I had connected MultiECUScan a few weeks ago to diagnose the engine light, which turned out to be a sticking wastegate. When I'd done, I tried to start it again to ensure the fault had cleared - it would crank, but not start. This was the first time the problem had occurred. I wondered what the hell I had done and disconnected the OBD device, after which she started fine. I thought no more of it until just now...

... coincidence, surely?

Probably not, but can't be ruled out at this stage

Back again when the battery's charged.

I will have to have a rethink

 

[Cook1e]

It might be tomorrow now. Mahoosive thunderstorm with an absolute deluge, followed by steady rain

Of course, I left the car window open

 

[Cook1e]

The rain bated off slightly, so I went to shut the window. The driver's seat is soaked!

I wasn't going to bugger about with it on a wet seat in the rain, but I tried to start it and it caught first turn, with a fully-charged battery