Injectors misbehaving but trying to understand the numbers

[MattBLancs]

Happy New Year

Yes think NBR is fine, there is a thread somewhere with the O-ring dimensions listed, I bought some based on what was listed there. I'll try and dig it out.

I don't think an air leak would cause a rough idle though??

I think an air leak is behind my non starting condition on my old C5 = can't draw enough fuel through at starter motor engine turn over speed hence does not build fuel pressure= non start.

Loads of air bubbles does suggest air getting in though.

[MattBLancs]

Yes think NBR is fine, there is a thread somewhere with the O-ring dimensions listed, I bought some based on what was listed there. I'll try and dig it out.

Found it
viewtopic.php?t=73185

[darbuck]

Thanks Matt, are you getting diesel at the injectors..
What exactly are the symptoms of the no start. Is she cranking at the correct RPMS. Have you got cam crank synch? She should run if you have cam crank and sync. Has it got a codes list?try and get some live data whilst cranking and pos up and we can have a look. You might be missing something.

[MattBLancs]

It's a bit since I've had chance to look at the C5 (too much other stuff going on!) I'll not derail your thread, quick answers and I'll continue my other thread when I get chance to have a look (next month I'd think)

Thanks Matt, are you getting diesel at the injectors..

Yes think so, but not done a leak off test as yet (bought a cheap kit for this a while back but not had a go yet)

What exactly are the symptoms of the no start.

Cranks over decent speed (starter is new, connections cleaned up, when happened in the past I tried a running car and jump leads to up the available current/voltage= no different)

It tries to fire (and from the logs, does so for fraction of a second - peak of about 7-800 rpm then down again) will do this repeatedly.

Is she cranking at the correct RPMS.

Yep, nice turn over speed

Have you got cam crank synch?

Yep

She should run if you have cam crank and sync. Has it got a codes list?try and get some live data whilst cranking and pos up and we can have a look. You might be missing something.

Currently theory is air ingress or backup hypothesis: high pressure pump is failing.

First time it did it, it was cured by a tow start = turning over the engine much faster was sufficient to get thf fuel flow.

It than ran PERFECTLY for, and think a couple of years! No further starting woes, no further tow starts needed.



Then it did it again, much to my surprise!

Jumped straight to a tow start= running again, ahhh, fixed again!


Nope, went to start it again a bit later and back to "just a cough" symptoms once more.

I'll fix it at some point (but it's days with me are numbered, regardless) just my fixing time limited is the hurdle :)

[MattBLancs]

My other thread!
viewtopic.php?t=71261
18 pages of frustration

[darbuck]

I'll post on your thread sounds like a weak pump or air in the lines.

[MattBLancs]

I'll post on your thread sounds like a weak pump or air in the lines.

Great, thank you, yes my thoughts too

[darbuck]

Have you tested the regulator?

[darbuck]

Ok so I have ran diagnostics over the past few days and I am getting fuel rail pressure of 260 bar instead of the Ideal 230. The reference value from the ECU is 260 as well so I am wondering if the ECU is lying to regulator at this point. It smooths out when it warms up but it still no where near right. I changed the fuel filter tonight to see if would help.
I'm wondering what could cause the high pressure in the rail. 20 to 30 bar is way out of tolerance but the car isn't flagging it.

I have been comparing data from the Peugeot 508 which has the 140bhp engine as opposed to the c5s138 bhp engine. They are more less the same engine. So a good reference. The main differences are the turbo Open cycle ratio which is 100% and the fuel pressure and injection opening times.

I did an injector leak off and they are very slow to leak off 25 mg in 4 mins. So injectors are good mechanically at least. I have listened to them with my stethoscope and they sound perfect and uniform. So given the fact that the injectors have essentially passed every test I can think of.
I can't see how I can look at them as culprits any further. A different regulator made no difference so I don't believe it is the pump or regulator either as there is no evidence of pump failure either. So I think I can say the ducting of the fuel system is the only possibility for an increase in fuel pressure. I know my obsession with this has become borderline nuts. I have to know what is causing it and I need to find it for my sanity at this stage.

[MattBLancs]

Morning,

Previously you'd smoking reported, has that cleared up?
Do you think it'd pass it's emissions testing as part of MOT / DCT?

I'm wondering if best thing would be getting it back into use - whether the uneven running is a symptom of the engine not having worked hard for a good while or even if the diesel is "getting a bit old" (I know petrol, particularly unleaded, degrades, reduces in octane, over time. To my knowledge diesel is more stable)

Perhaps getting some miles under its belt and see how it responds might be best?

[darbuck]

I'm thinking the same at this point. I'm just afraid of doing damage to the components I have changed. Maybe it just needs a good run I am waiting on a rad to try it and it needs a gasket on the egr. After that I think I will put it together and see how I get on. Hopefully it will work and not blow something.

[Muir]

It's just a theory as these moderns ECU's are vastly complex, but like Matt says it may just need to have a good run to properly map out it's volatile memory.
I've never paid much attention to fuel rail pressure without due reason, but have noted on two of my cars that MAP pressure/boost pressure was not in line with reference unless the car was running under load.
It never seemed to cause any issues either - even though the boost was actually under reference point neither car ever smelled/smoked or ran poorly.

Point being I think you may need to run it through it's paces with various loads at various RPM, so the ECU can do some fuel, boost & load mapping.
It might not help any bit, but if the car runs & sounds good I wouldn't pay too much attention to it.
If nothing else I've often found my cars really liven up when driven hard for a bit.
Both reactivity and power increases, but of course so does consumption

Ps. I usually drive like a 80yo grandma fueled on cooking sherry.

[darbuck]

Yeah I think so too, I'm just concerned because it doesn't sound right especially on start up. As I said I need an egr gasket and rad.once I have them fitted and finish putting the front of the car back together.

It depends on the granny some go asleep some go bananas. Either way funny image.

[darbuck]

Ok so I can't drive it the way it is but there is something in the dat that's different. I have looked at egr valve and it says not programmed not regulated and 0% open. I don't know why it is not throwing a code through. It sounds horrible. If I rev it now there as an awful amount of pinging and knocking. I need to figure out how to test the egr valve. It took a four attempts to get it started as well. I know it's cold but not cold enough for this.

I tried doing the learn procedure and it said it was done but obviously it wasn't

[MattBLancs]

As well as learn, there's also "actuator test" have you given that a go for the EGR valve? (Cycles it without the engine running so can hear it it's doing anything)