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Technical Multijet no start.

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Technical Multijet no start.

The air was from the low pressure side. Engine idled and revved normally.
The main pump, injectors and valve leak-off all feed into a separate area (chamber?) at one end of the rail. I’ll take a picture when I get the valve off the rail.
Normally the main pump leak off would have flushed any air back to the fuel tank. I had redirected that direct to the tank. Injectors had their own bottle and the “chamber” was flushed only by the valve leak-off.
 
Time base on you graphs is seconds right ?

200 rpm with no compression in not correct ?

You have done the basics, powers, grounds, voltage drop tests
 
There was no signs of air in the high pressure area. Engine started and ran smoothly. It’s just what’s trapped in the low pressure “pot” around the pressure control valve.
I had removed all hoses to & from that area to redirect for tests. It would have air.
 
koalar said:
Time base on you graphs is seconds right ?

200 rpm with no compression in not correct ?

You have done the basics, powers, grounds, voltage drop tests
Click to expand...
Earth drop tests all show very low resistance. Adding jump leads to support engine main earth make no audible difference to starter sound. Battery is a 500 amp

The times on graphs are MES standard. They are obtuse so I’ve not tried to be clever by playing with them.

The cranking test was with zero compression. I did not check dash engine tach for cranking speed. Buts it’s easy enough to repeat.
 
The main fuel filter sees about 5 bar from the fuel tank pump. Slightest leak would P fuel out. Air in the low pressure end of the common rail was expected because I had redirected the injection pump and injectors leak offs. It had only the pressure regulator overflow/leak off to clear it out.

Injector leak-offs at idle speed.
#1 - 12ml per minute.
#2 - 16ml per minute.
#3 - 15ml per minute
#4 - 11ml per minute.

Tested one by one with a tube plugged into the leak-off port and the connectors capped with a suitable crimped neoprene tube.
Flow was allowed to stabilise (about 1 minute) then collected over a timed minute.

The new pressure control valve arrived. Genuine Bosch with the correct numbers. No change. Immediate hiccup and low pressure fuel flags up. It’s looking like that “new” injection pump I bought last year was not what it purported to be.

I suspect the starting is slightly worse. It seems to stumble into life. Previously it fired smoothly after 1 second of cranking.
 
DaveMcT said:
The main fuel filter sees about 5 bar from the fuel tank pump. Slightest leak would P fuel out. Air in the low pressure end of the common rail was expected because I had redirected the injection pump and injectors leak offs. It had only the pressure regulator overflow/leak off to clear it out.

Injector leak-offs at idle speed.
#1 - 12ml per minute.
#2 - 16ml per minute.
#3 - 15ml per minute
#4 - 11ml per minute.

Tested one by one with a tube plugged into the leak-off port and the connectors capped with a suitable crimped neoprene tube.
Flow was allowed to stabilise (about 1 minute) then collected over a timed minute.

The new pressure control valve arrived. Genuine Bosch with the correct numbers. No change. Immediate hiccup and low pressure fuel flags up. It’s looking like that “new” injection pump I bought last year was not what it purported to be.

I suspect the starting is slightly worse. It seems to stumble into life. Previously it fired smoothly after 1 second of cranking.
Click to expand...
I have no idea what what a good reading on these engines should be

The only test data I have is for a different car

Fuel at 50C
2 mins idle
30 seconds at 3.8k RPM
30 seconds at idle
30 seconds at 3.8k RPM
30 seconds at idle
30 seconds at 3.8k RPM
30 seconds at idle
Max 25 ml

11 to 16 is a 45% difference with such a short test time are you sure it's not a measurement error
 
If could be measurement error but I ran the engine until drips were consistent then did a timed minute at idle. 25ml over the recommended times is considerably less flow than I’m getting.

That all said, it was running fine before I replaced the cylinder head. No EML just symptoms of weak compression on one cylinder.
 
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We haven't done the basics and keep changing things in the hope of fixing it

We don't have over 200rpm at cranking we only have 203 with the plugs out

We don't have over 300 bar before the injectors fire
Good ones are over 400 normally

We have done a proper test cranking Vs pressure

We haven't looked at the duty cycle of the fuel metering

We haven't looked at the duty cycle of the pressure regulator

This is what they should look like and a working car at idle

Screenshot_20240725-152125.png


Is there any glitter in the bottom of the fuel filter housing, shine a bright light
 
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I’ve given up chasing my tail on this. The injectors have software adjustments well within range and the engine runs clean at idle. They won’t be perfect but they are not significantly out of spec. I also don’t have the means to spend megabux on special tools to use just once.

I believed the “new” pump was actually new but I strongly suspect it was used. It was about 1/2 the cost of service exchange. The pump from the car leaks from a cylinder head. A new seal kit failed to fix it.

I’ve now fitted a new pressure sensor which actually makes matters worse. Interestingly it runs better with the sensor unplugged. Not something I’ve tried before. Too scared of over-pressuring the system. It tells me the normal pressure regulation is too much for the pump to supply.
 
Remanufactured pump from PF Jones installed and running. It started almost immediately despite there being air in the system from swapping out major parts.
It accelerates cleanly with no low pressure errors coming up. I can’t do a long test as mot ran out. But it’s definitely improved.

I have now got an uneven idle like it’s switching off momentarily then going back on. That’s new - it was completely smooth. But it has new pump, new pressure control valve and new pressure sensor so it probably needs to settle down.

MES shows no injector errors and adjustment values have not changed. I will need to get the licensed MES for that.

I wonder if a wonky crank sensor could cause that issue. Though I’m told they ten to work or not work.
 
DaveMcT said:
Remanufactured pump from PF Jones installed and running. It started almost immediately despite there being air in the system from swapping out major parts.
It accelerates cleanly with no low pressure errors coming up. I can’t do a long test as mot ran out. But it’s definitely improved.

I have now got an uneven idle like it’s switching off momentarily then going back on. That’s new - it was completely smooth. But it has new pump, new pressure control valve and new pressure sensor so it probably needs to settle down.

MES shows no injector errors and adjustment values have not changed. I will need to get the licensed MES for that.

I wonder if a wonky crank sensor could cause that issue. Though I’m told they ten to work or not work.
Click to expand...
Pleased for you Dave, when you have the new MES it will be interesting to see the rail pressure and revs across the range.:)
 
Shouldn't be any air in the system, you suppose to prime the system for a couple of minutes, before starting, to prevent premature wear, the pump that is cooled and lubricated by diesel, there's normal a prime function within the scan tool software

The free version of multiECUscan is fine for plotting engine data on a diesel just limited to 15 minutes

The car was working fine, before the chain broke, we've changed everything, adjusted things, rebuild things, we have no way of knowing what's working what's not, plus we have some broken connectors and hard to seal fuel filter

If you touch the bear minimum, and there is a problem, you know which bits to look at first.

If you suspect a fail on fit pump, you could have put the original back on

We still haven't got any data on fuel pressure at cranking speed and what the cranking speed is which was ask back in July 8

Vauxhall 1.3 cdti was around 400 bar, you had around 250 bar what are we getting now
 
DaveMcT said:
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.

View attachment 448466
Click to expand...
email them and ask. I find they are unusually helpful.
 
The fuel filter unit was replaced early on to remove the high fuel temperature fault code.

We don’t have a confirmed cranking fuel pressure because I don’t own £200 worth of test gauge and fittings. I can only offer what the ECU sends out. It won’t go above 38,000 baud which is pretty slow.

The HP pump originally fitted to the car had a leak from a cylinder head. Despite new seals, it was unusable.
I bought what was supposed to be new. It clearly was not. But to be fair the price was not high.

The remanufactured pump was given a dose of diesel after fitting to make sure it had some lubrication on startup. But the hard line was dry and the pump was not flooded to as void mess. There would be bubbles in the HP system. There is no bleed point on the common rail.

The HP pressure drop on throttle pedal down has ceased. I’ve not had time to run any further tests but a spin around the block seemed good. BTW there is no random glitch or dip showing on the rev counter. I presume that means the crank sensor is going it’s job.

EGR is behaving itself for now. No odd warnings of any type from that area.
 
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