Technical 169 Multijet Intermittent Hard Starting
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Technical 169 Multijet Intermittent Hard Starting
4,000-something from memory. I'll confirm/correct next time I'm in the car
Post a graph of the fuel pressure, while it's failing, you should be able to see the pressure rise as its cranking and then falls the injectors opening
Also post a graph of the MAF sensor while cranking and failing, It will have really low values if the throttle body is sometimes gets stuck, when compared to being open(yes I know it's not really a throttle body)
If the EGR was stuck I would expect an error code, I don"t have the diesel engine, I think in multiECUscan you can open and close it,
it would be helpful if someone posted to read outs from a working 1.3D
Also post a graph of the MAF sensor while cranking and failing, It will have really low values if the throttle body is sometimes gets stuck, when compared to being open(yes I know it's not really a throttle body)
If the EGR was stuck I would expect an error code, I don"t have the diesel engine, I think in multiECUscan you can open and close it,
it would be helpful if someone posted to read outs from a working 1.3D
Morning all,
It stopped raining an hour or so ago, so I have more info and a tentative diagnosis...
...and a wet arse despite sitting on a plastic bag
Attached a couple of MultiECUScan screenshots, but not really informative, because (with a fully-charged battery) it started first or second turn every time for about a dozen tries. I therefore tentatively conclude that low battery voltage is the most likely cause of the failure to start.
I confess that 90% of my trips are 5 miles or so to the shop and back, so maybe it's not always charging fully. I'll start carrying a jump-pack and keep an eye on it, repeating the MultiECUScan graphs when the problem returns.
I checked the battery earth - less than 0.1 volts between battery negative terminal and the engine block, so no problem there. The MES data show battery voltage is healthy: more than 10.5 volts during starter engagement. The MES graphs show the other data folks have asked for - all seem good.
I'll leave the thread open for when I have more information. Thanks to all the contributors for your thoughts and suggestions
It stopped raining an hour or so ago, so I have more info and a tentative diagnosis...
...and a wet arse despite sitting on a plastic bag
Attached a couple of MultiECUScan screenshots, but not really informative, because (with a fully-charged battery) it started first or second turn every time for about a dozen tries. I therefore tentatively conclude that low battery voltage is the most likely cause of the failure to start.
I confess that 90% of my trips are 5 miles or so to the shop and back, so maybe it's not always charging fully. I'll start carrying a jump-pack and keep an eye on it, repeating the MultiECUScan graphs when the problem returns.
I checked the battery earth - less than 0.1 volts between battery negative terminal and the engine block, so no problem there. The MES data show battery voltage is healthy: more than 10.5 volts during starter engagement. The MES graphs show the other data folks have asked for - all seem good.
I'll leave the thread open for when I have more information. Thanks to all the contributors for your thoughts and suggestions
Thanks for taking the time to post the graphs, it will give use a good base linel
0.1V while cranking is really good result.
0.5V is suppose to be the maximum total on both sides, you test the positive side and negative side seperately and add them together
I have measured close to 0.5V just on the negative side on a working car so there obviously some leeway
If you are getting good crank speed and the alternator, oil pressure, engine check lights are behaving correctly
It's almost certain the fault lies elsewhere
As you have already said it starting to point towards the battery
But it still need a little more testing to sure maybe voltage, RPM and fuel pressure on one graph and compare when working against when it's not
Of cause if it's failing but works fine with the jump pack that would be fairly conclusive
I'm sure I'll be back before long - an issue like this will certainly recur at the most inconvenient time
Do you have enough pressure at the commonrail? IIRC 1250+ bar. There should be a sensor on the common rail. Usually they are sealed with an O-ring that can fail and loose pressure.
gr J
gr J
Not showing as a fault. 4000+ psi at idle rising to twice that at 2,000 RPM or so. If o-ring failed, I guess there would be a leak?
could leak internally loosing pressure without loosing diesel.
I know this is a problem on older MB CDI's (MB bought the commonrail know how from Bosch , who bought it from FPT, Fiat PowerTrain).
How much Bar is 4000 Psi?
gr J
I know this is a problem on older MB CDI's (MB bought the commonrail know how from Bosch , who bought it from FPT, Fiat PowerTrain).
How much Bar is 4000 Psi?
gr J
Official test
Disconnect the electrical connections from all the fuel injectors.Disconnect the fuel recirculation pipes from all the fuel injectors.
Connect the diagnostic equipment (Examiner or Examiner Plus)Connect the diagnostic equipment (Examiner or Examiner Plus)Turn the ignition key to the start (AVV) position for 5 seconds and check that the fuel pressure is over 300 bar with engine speed of about 200 rpm.
@Cook1e is getting nearly 5K psi on cranking until the injectors fire on a fresh battery
300 bar = 4351.132 psi
Disconnect the electrical connections from all the fuel injectors.Disconnect the fuel recirculation pipes from all the fuel injectors.
| Restrict the injector recirculation pipe so that no fuel can come out during the test. |
@Cook1e is getting nearly 5K psi on cranking until the injectors fire on a fresh battery
300 bar = 4351.132 psi
Just looked that up. 4000 Psi = 275 Bar. So not enough pressure for the injectors I guess...
gr J
gr J
May be unrelated but at the beginning of your thread you mentioned injector cleaner, did problem got worse after that?
I had a 03 Doblo diesel van that injector cleaner in the fuel tank affected the sealing of the plastic fuel pipe connections at the tank allowing air into the system.
It seriously affected starting but once running it was OK.
I had a 03 Doblo diesel van that injector cleaner in the fuel tank affected the sealing of the plastic fuel pipe connections at the tank allowing air into the system.
It seriously affected starting but once running it was OK.
That's a new one Mike, I just added the injector cleaner the other day, not many miles since. It can't be the cause of this problem, but worth knowing in case of future issues
It was an older non turbo version and used the injector pump to "suck" the fuel from the tank, no pump in tank.
At the time Fiat wanted £200 for the flow and return plastic pipes, so I repaired using fuel grade pipe and crimp on clips which cured it.
Re yours, a fuel filter slight seep can allow air in when stopped, so if left for a few days worse , but if you restart soon after a trip probably OK.Usually if you run your hand around the filter and any fittings then see if fuel smell/wetness.
At the time Fiat wanted £200 for the flow and return plastic pipes, so I repaired using fuel grade pipe and crimp on clips which cured it.
Re yours, a fuel filter slight seep can allow air in when stopped, so if left for a few days worse , but if you restart soon after a trip probably OK.Usually if you run your hand around the filter and any fittings then see if fuel smell/wetness.
That would explain the problem, but I think if there was a leak I would smell diesel under the bonnet. Definitely no leak.
From a working punto multijet fuel rail pressure cold is about 198 bar at 165 rpm
Curiouser and curiouser...
It's only played up once since I last posted. Unfortunately for my 'slightly low battery' hypothesis, it took 3 goes to start, having been parked for about 10 minutes after a 100-mile round trip, when the battery must have been fully charged and the engine had been at full running temperature for more than an hour.
I will wait until it either fails to start entirely (I need some value from my recovery service) or throws a code.
Watch this space, but don't hold your breath
It's only played up once since I last posted. Unfortunately for my 'slightly low battery' hypothesis, it took 3 goes to start, having been parked for about 10 minutes after a 100-mile round trip, when the battery must have been fully charged and the engine had been at full running temperature for more than an hour.
I will wait until it either fails to start entirely (I need some value from my recovery service) or throws a code.
Watch this space, but don't hold your breath
Belated update, because there's damn-all to update...
It has been hard to start only a couple of times since my last post - both times after running for a few miles, stopping and then trying to start again 10 or 15 minutes later. Each time, it finally started on the 3rd or 4th go.
It's in for a service next week and I'll ask him to check out the whole diesel system, leaks, water in the filter, pressures etc.
Maybe more soon, stay tuned...
It has been hard to start only a couple of times since my last post - both times after running for a few miles, stopping and then trying to start again 10 or 15 minutes later. Each time, it finally started on the 3rd or 4th go.
It's in for a service next week and I'll ask him to check out the whole diesel system, leaks, water in the filter, pressures etc.
Maybe more soon, stay tuned...
