If I leave the car overnight, the car starts but now 5 seconds into the idle it stumbles really bad. Lately it actually stalls. If i don't bring up the rpms to over 1000, it'll continue as if i have a lot of air in the system . My poor new engine mounts!
What's really odd is that this did not happen when the car was parked with the front of the car low. (friends steep driveway)
The car does have an injector clutter between 1k-2k rpm. Just did injector leak test and it looks good accross all 6. Seems like 8 hours of not running the motor is enough to cause this starting stumble/poor idle to show up.
I should add that I was not getting any error codes
Any ideas? Many thanks.

 

Got my hands on xentry. It shows:

Event 2918, Test components Y85 ( Egr/Agr cooler bypass flap switchover valve ) and B90 (Egr/Agr cooler bypass flap hall sensor) . Component B90 reports state " bypass flap closed" although components Y85 is actuated.
And the second event says B90 reports "bypass flap open" although Y85 is not actuated.

Is my intake manifold all carboned up?

 

I also checked "fuel injector quantity correction adjustments at idle +-5mm" - all within spec.
There are few negative numbers ( see attached images). Are these idle values OK?

The test did not increase RPMs. Do I have to rev it up and see if the values stay within +-5mm over the range of RPMs?
Third image shows steady pressure of the high pressure so that's OK.
Thanks

 

Run it again at idle after playing with DAS and got two codes; (great!)

2021-001
2051-001

Rail pressure monitoring via pressure control valve. The rail pressure is too LOW.

So I run "Check components of high pressure control circuit" in DAS and looks OK.
It also run fuel injector qantity corrections and it looks ok, actually closer to zeros than the first time

 

Those injected quantities are perfectly fine.

Test the Y74 (Fuel Regulator on the drivers side rail). It controls engine fueling for the first 30 seconds its started, then the Y94 (Quantity control valve) takes over.

 

DAS instructed to check for ohms accross the Y74 sensor. Accepted range is between 3 and 5 Ohms. I get 4.3Ohms.
I also run and old event that showed problem with Y74 and it passed. (Attached picture of idle results and ignition on position 2)

I also checked injector quantity correction values at higher rpms and at around 4k , numbers are much higher for injectors 3 and 5. I do get a major injector clutter noise from time to time in the low rpm range. (Image attached)

 

Also run DAS "Test of compression" and got compression OK.

 

Your injectors are fine. Leave them alone.

There are two tests for the Y74 that you've ran and one of them failed. The internal resistance is fine, but the internal leak-tightness test proved it is not. This is the common one that fails and causes your low pressure codes. The rail must be replaced.

 

I thought that since the Y74 on/off ratio I got was less than 30%, the valve was OK?

 

I misread the value. Test the rail pressure sensor on the passenger rear side. Have you replaced the fuel filter?

 

My fuel filter is only 1 year old and has 12k miles but perhaps ill take it apart and see what I find. Will investigate the B4/6 sensor. Thanks!

 

I just recently changed my filter at the 1 year mark (20k miles) and it was damn near completely plugged. If both of those check out, I would proceed to a injector leak test.

 

Xentry only instrusted to check power supply to B4/6. There are no tests available that test this sensor, unless I missed it?
My reading was within range. I'm including images for reference.
I have recently performed injector leak test and that looked ok. I tried to do that again with the guidance of xentry but I can't find this test. Where is it?
Given that there are no codes that would signal failed B4/6, I'm leaning toward fuel filter issue. I'm really going to be surprised if I find it clogged as diesel filters historically were good for years.

 

Could be getting air in the fuel system somehow, maybe a small leak? When you start it in the morning, have you tried to leave the car in the on position for about 5-10 seconds before starting? If you have keyless-go, press the button twice without stepping on the brakes, wait 5-10 seconds, then step on the brake and press the button to start the car.

 

Great idea! This was my original hunch and I did checked for leaks and found none, no smell of diesel fuel. This morning however, I had ignition on for 15 sec and it DID start without stumbling. Perhaps this was this one odd time that it periodically starts smooth. It wasn't a perfectly smooth idle though (~50RPM fluctuations) but much better! Will check on all the connections again.
Perhaps fuel pump is the issue?

My DPF looks good. Have a peak.

 

I would think fuel pump but it only happens when it sits overnight, so I’m hesitant to say that. I would try the ignition thing again to see if it was luck or real. The system is self purging so pending when you test could show no leaks. May also be small enough that it’s not detected after first start up.

 

I have not changed the fuel filter yet BUT so far I had the car start 6 times with the igniting on for 15 seconds and it idles OK! Not perfectly steady but hey, no stalling. Few times crank time to start was longer than usual but it has not stalled even ones.
To be honest, I'm not sure what to think.
I'll take apart the filter tonight and see if I find any metal shavings.

 

If the filter is plugged, letting the fuel system run longer before starting will let it adequately pressurize. No need to cut the filter open, just drain it completely and clean the inlet off and blow in to the inlet with your mouth. you'll immediately know if its blocked.

 

this. There is definitely something stuck somewhere causing insufficient pressure at start up.

 

It's definitely NOT the fuel filter. Just tested...

 

Have you manually tested the fuel pressure from the low pump?

 

No, not yet. Unfortunately I don't have the guages.

 

I have not checked supply fuel pressure yet but this morning, the car would not start for 2 full start cycles. I had the ignition on for 2 min prior to starting.
It was cold outside so outdoor temperature is the factor affecting starting. I have no codes but I'm thinking it must be some sensor. My guess is the cam sensor. I don't have a scope to check it so I'm thinking of just getting one and see ...

 

To give an update, got some spare parts. Actually many... Installed the cam sensor and this morning (5 degrees Celsius), started right up! I turned the key just after the glow plugs light went off.
Keeping my fingers crossed.

I should add that I decided to tear open the fuel filter. I inspected it carefully for any metal particles and found no aluminum nor any metal.

 

Glad it all worked out man!!