Technical Multijet no start.

[DaveMcT]

The HP injection pump has three (very short stroke) pistons running at 50% engine speed so makes 3 pulses per 2 crank turns. I’m guessing to avoid harmonics between pump and injectors which fire twice per engine revolution. The fuel rail is large enough to absorb pressure pulses.

 

[bugsymike]

Re the injection pressure fall off at common rail, both the other ones I tested to compare with Dave's were same age vehicles and the rate of decline allowed me to take several photos over at least 15-20 secs. as I am not David Bailey with a camera.
Be interested to hear of others results re this.

 

[koalar]

Op

My instincts are that given the pump in tank was powerful at filter when we blocked it, but every time the ignition is turned on the tank pump restarts I suspect somewhere between fuel filter and common rail it is losing that pressure, possibly around the high pressure side Fuel Pressure Regulator allowing pressure to be lost back to tank via return system. As most systems once tank pump has built up line pressure to high pressure pump then tank pump stops or only runs for a short time.
So either dirt or a sticking valve in regulator most likely. I would have said a possible issue with return pipes but it does seem to be intermittent , where as that would be constant.

The ECU sends a signal to switch the pump on every single time the ignition is turned on, regardless of the pressure,

On cranking the pump is on permently, pressure is regulated via a valve built into the pump

We did get roughly 260-270

Disconnect the injector fuel recirculation pipes and block

crank for 5 seconds
pressure minimum 300 bar with rpm above 200 rpm

When it wasn't starting up Bar reading on MaxiECU was 7Bar,

Fairly obviously not correct

Seeing as this was not the original fault, it likely to have been introduced since

 

[bugsymike]

Op


The ECU sends a signal to switch the pump on every single time the ignition is turned on, regardless of the pressure,

On cranking the pump is on permently, pressure is regulated via a valve built into the pump



Disconnect the injector fuel recirculation pipes and block

crank for 5 seconds
pressure minimum 300 bar with rpm above 200 rpm



Fairly obviously not correct

Seeing as this was the original fault, it likely to have been introduced since

I am not disputing any of the above , my point was that once the signal to the ECU to activate the injectors is disconnected, then in normal circumstances the fuel pressure within the Common Rail progressively falls to zero via leak off past injectors etc. Where as in this case the drop was instant. Which I suspected to be a fault in the pressure regulator on the Common Rail.
I accept this can be via a faulty signal from the fuel filter temp sensor sent to the pressure regulator, although I was unaware of that possible controlling influence and was looking towards a mechanical fault such as a dirty or sticking fuel regulator which could have a similar effect
So perhaps an MES user can see if my claim can be corroborated, or not as to gradual fall off of pressure at the common rail on engine shut down.

This was from Pico Diagnostic library notes, which indicate my point, I have seen similar on Bosch sites online.

The rail pressure sensor is calibrated to output a signal between 0.5 V and 4.5 V with changing rail pressure across the range 0 bar to 1600 bar. This provides two opportunities for the ECM to undertake a signal plausibility check: any voltage above or below these values, for example, either at 0 V or 5 V, will indicate that the sensor has failed. "A high-pressure system leak can be indicated if the sensor output rapidly drops to 0.5 V after the engine has been stopped, as might occur with a leaky injector, rail pressure regulator, inlet metering valve or pump."

 

[koalar]

1.3d cdti combo, this vehicle had a faulty EGR valve, nothing to do with fuel

Lift pump

At the pumps output

At the common rail

No PWM signal at the pressure regulator solenoid it's going to drop quickly ?

 

[bugsymike]

Surely the second video shows what I was saying, though you were reading physical pressure and my readings were from the scanner.
On Daves Panda as I watched the pressure dropped to nothing instantly, not the progressive fall when it died as your and my tests.

 

[koalar]

Surely the second video shows what I was saying, though you were reading physical pressure and my readings were from the scanner.
On Daves Panda as I watched the pressure dropped to nothing instantly, not the progressive fall when it died as your and my tests.

No that at the HP pump outlet, before the pressure regulator or injectors,

Video 3 is what the sensor is seeing at the common rail

As soon as the cranking stops (pipe shaking) it's reading zero

 

[bugsymike]

No that at the HP pump outlet, before the pressure regulator or injectors,

Video 3 is what the sensor is seeing at the common rail

As soon as the cranking stops (pipe shaking) it's reading zero

So the Pico library of results is incorrect?

 

[koalar]

So the Pico library of results is incorrect?

You wanted the results from the same engine, I have done my best to provided them? Not my video I don't own a MJ, but its the same engine and controls

What engine is in the Pico Pico library ?

Some engines the pressure increases after shut off
Some tail off over time
Some just drop

And just about anything in-between

This Audi doesn't drop off it doubles, which is handy as you can see if any injectors are leaking, but it doesn't match the Pico library I was looking at

 

[bugsymike]

This one is on a BMW Pico used as a demo test bed if you want to follow their uTube video :-https://www.youtube.com/watch?v=yF0HF5T2qLg.
As they do training courses for the Motor trade on their products and are highly regarded on the subject, I tend to accept their knowledge.
Regarding the Audi I can understand when in a hot environment fuel trapped in the Common Rail in a diesel engine with minimal "leak off" to lose pressure and the fuel not circulating then pressure could rise with temperature when switched off due to not circulating back to the fuel tank, though hardly a common occurrence and maybe made worse by really tight tolerances. Much in the way a coolant temperature rises when engine switched off so water pump not circulating the coolant and why many engine compartments have a warning that the electric fan may cut in due to heat build up.
Regarding "some just drop" I suspect that to be a symptom of an underlying issue such as worn injectors causing hard starting, commonly proved by a "leak down " test involving measurements at each injectors leak off pipe.
I suspect we shall have to agree to disagree.

 

[DaveMcT]

When I get the chance, I will get some traces of the MJ fuel pressures. However I’ll need to upgrade MES as my free version says “full licence required” when I try to graph the data. It also won’t let me reset the learned data for injectors. So I need to get the licence.

 

[koalar]

There's no check valve unlike the Audi
There's no signal to the pressure regulator so set to minimum

It's a completely different system

Different system will behave differently



Start with the basics

Unplug the electrical wire from the injector

Attach the scantool

Measure the pressure and rpm

Minimum 300 bar at 200 rpm

If you have that move on, if you haven't investigated further

There's no limit in using the free alfaobd except bidirectional tests

Never used the PC version though

SCANMASTER-ELM should also work

 

[DaveMcT]

I’ve just run my (free version) MES on the 2007 Panda 1.2 dynamic. No faults and everything seems ok. I can read a long list of Parameters about the engine. Graphs also work.
I went over to the Multijet but the parameter list shows no values and of course graphs all show zero.
Is this something the licenced MES (“paid for”) will sort out?

 

[koalar]

I’ve just run my (free version) MES on the 2007 Panda 1.2 dynamic. No faults and everything seems ok. I can read a long list of Parameters about the engine. Graphs also work.
I went over to the Multijet but the parameter list shows no values and of course graphs all show zero.
Is this something the licenced MES (“paid for”) will sort out?

No

Not unless you have the

Marelli 8DF CF5 ECU, which you said earlier you didn't

Or their websites is wrong

Or I can't read it wright

Try alfaobd free

Is that blank as well

 

[DaveMcT]

Mine has MJD 6JF ECU. It’s listed in MES and it finds the fault codes. I don’t mind paying the license fee. Just need to know it actually will unlock the stuff I need.

EDIT - I’ve just looked at Gendan website. It doesn’t have the necessary details to know how MES would behave on the MJ.

 

[bugsymike]

There appears to be a different list from 2012, but is this like yours? https://www.gendan.co.uk/category_161.html

Fiat Panda '03 1.3 JTD/Multijet

Marelli 6F3 EOBD Diesel Injection (1.3) |INFO|DTC|DTC EX|PRM|ACT|ADJ| KLELM Marelli 6JF EOBD Diesel Injection (1.3) |INFO|DTC|DTC EX|PRM|ACT|ADJ| KLELM Marelli 8DF CF5/EOBD Diesel Injection (1.3) |INFO|DTC|DTC EX|PRM|ACT|ADJ| KLELM Bosch ABS 8 |INFO|DTC|DTC EX|PRM|ACT|ADJ| KLELMA1P1 Bosch ABS 8 ASR |INFO|DTC|DTC EX|PRM|ACT|ADJ| KLELMA1P1 Bosch ABS 8 VDC |INFO|DTC|DTC EX|PRM|ACT|ADJ| KLELMA1P1 TRW Airbag 2 (Ep - PROXI) |INFO|DTC|DTC EX|PRM|ACT| ELM TRW Airbag MY99 |INFO|DTC|PRM|ACT| KLA2P3 Delphi Electric Steering |INFO|DTC|PRM|ADJ| KLELMA1P9 Service Interval Reset (Base) |INFO|ADJ| ELM Service Interval Reset (Comfort) |INFO|ADJ| ELM Connect (NAV) Marelli |INFO|DTC|PRM|ACT|ADJ| ELM Instrument Panel Marelli (Base) |INFO|DTC|PRM|ACT|ADJ| ELM Instrument Panel Marelli (Comfort) |INFO|DTC|PRM|ACT|ADJ| ELM Body Computer Siemens |INFO|DTC|PRM|ACT|ADJ| ELM CAN Info |INFO| ELM CAN Setup / PROXI Alignment Procedure |INFO|ADJ| ELM Denso climate control (Single zone) |INFO|DTC|DTC EX|PRM|ACT|ADJ| ELM

 

[koalar]

Let's just get something working anything and worry about getting multiECUscan up and running later. At this stage we only need basic scan functions

To read the engine parameters it doesn't even need to be fiat specific

I use a £5 elm327 and torque on an android phone 99% of the time even though I have access to Delphi and WoW with a multiplexer

There's dozens of pieces of software to tried, with a USB elm327 and windows laptop

It shouldn't take long to unplug the injectors, and read the pressure and rpm so we can move forwards

 

[DaveMcT]

this morning the engine is running fine. Despite the glow plugs not working, it started with no more cranking than the petrol Panda.
The test run last night lurched a split second later came back but put the engine light on. The code was for low fuel pressure. It reset all codes and engine started fine.
The shutoff and return was so sudden it had to have been commanded. A weak pump would have surely caused a stutter and (later) weak starting.

As said, I’m waiting for a new fuel filter. I’ve checked the loom and connector but see any wiring problems. That area has not been disturbed so it should be fine.

A resistor into the plug contacts would prove the wiring, but I have no idea what would be correct value.

 

[koalar]

 

[koalar]

Just read the values

Plenty of software out there for

Windows
USB ELM327

MultiECUscan is not the only option