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Discussion Starter · #1 ·
Diagnostic please peeps...

Erratic tick-over and black clouds at the back when accellerating... any ideas?
 

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Discussion Starter · #3 ·
Thanks Goudy. Gives me somewhere to start.
 

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When you're driving and you hit the gas, does it make any noises?
Whooshing, hissing, farting noise from under the bonnet and reduced turbo boost?
The air intake pipe under the EGR is prone to splitting.
Also the jubilee clips holding the air pipes onto the intercooler down the front can rust away and pop off.

EGR could have failed and it's choking the engine.
To test, split the exhaust feed off it (steel pipe that pumbs in from the right) just undo the two nuts and pull/swing it away.
Fashion a blank out of a tin can or thin alloy sheet (use the metal gasket in the joint as a template).
Bolt it all back together with the blank in that exhaust feed joint.
If it runs better blanked off, it wants a new EGR valve.

The MAF wiring on the connector may have broken, there isn't much slack in the cables, so inspect them carefully.
Hard to tell if the MAF is giving a duff signal, a diagnosic tool that gives live data helps (also knowing what it should read helps too)
I guess it won't hurt to visually inspect the hot wire in it and a squirt of electrical cleaner may shift any shite on the hot wire.
 

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Discussion Starter · #5 · (Edited)
Ingredients for a heart-attack.

Thanks for the detail. I'll try and find time to have a look at the EGR on Sunday. It's never been off in the 4-5 years she's had the car, and judging by the state my old one was in I'd sudder to think what this one'd like!

No noises that I've noticed - my old 2.0 suffered from split 2 egr hose...

Had a major panic tonight though...

When I replaced the fuel filter on my old 2.0 Euro 4, I simply switched the old and the new, and cranked it over to pull the diesel through and it eventually started...

Replaced the filter on my wife's non-Euro 4 and almost flattened the battery trying to start it. Nothing... Took the hoses off to see if the fuel was getting through... nothing... not a drop!

Nipped out and bought a gallon of diesel and with a small jug, poured somwe of it into the new filter - all spouts - until they overflowed. It started! But... it's still erratic. Starts fine, then drops, to almost cutting out, then picks up again... feels like the tickover is on a roller-coaster...

Am I being paranoid, or does this feel like fuel pump failure? To me, it it was it wouldn't start at all as the fuel needs to be injected into the cylinders - it's not like the old 4 stroke pulling the fuel in!
 

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It ran ok before you replaced the fuel filter?
Is it a Delphi or Bosch filter? I hear they don't like cheap pattern filters.

You may still have air in the system.

Is this the car with the black smoke and the suspected EGR fault?
If it's a vacuum EGR with no sensor/wires, clean it out and blank off the exhaust feed, doesn't matter then if it works or not.
If it's sticking open, it'll be choking the engine of air.
 

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Discussion Starter · #7 ·
No. Tickover was erratic before I did the filter. As it's a while since it was changed I thought it a simple place to start.

Cleaning the EGR today (weather permitting)

My *big* concern is the lack of diesel when I disconnected the filter. Is it normal for no fuel to be pushed through? If there is air in it, is it a case of loosening the injectors to bleed the system, as I had to with my 2.0 ran out of diesel, or is there another way of doing it?

I've been reliably informed that blanking off an EGR results in premature turbo failure as the EGR helps to keep the exhaust gas temperature down. Must admit when I got rid of my 2.0D SE the turbo was starting to whine - and *yes* I had blanked off the EGR...
 

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I've never had to bleed my X, but on other diesels I've undone the union to the injector, the one furthest away from the pump and cranked it until fuel pours out.
Not sure this was is ideal on a common rail though, what with the much higher rail pressure, I believe the trick is to crank the engine until they purge themselves.

Blanking your EGR isn't going to effect the turbo.
Yes the EGR introduces exhaust gas into combustion chambers, which lowers combustion temps, but it should only do this on slight throttle openings which the turbo will be on low or little boost anyway.
When the turbo working hard, EGR operation wouldn't/shouldn't be taking place, hence it would effect the turbo.
 

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I'm pretty sure that the EGR is most active at high load - as that's the time the combustion temperatures are highest and therefore NOx production high. The possibility of Turbo damage was discussed a while ago in one of the many EGR / blanking posts but no one (on this site at least) has experienced turbo problems after blanking it off. I suspect that few people are able to find enough road space to keep the car running flat out for an extended length of time and run into overheated turbo problems regardless of whether they've blanked off the EGR.

Ian C
 

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I seem to remember reading EGR operation should cease when wide out throttle is approached.

I lifted this
the EGR valve opens during light throttle and warm engine cruising and
channels the exhaust gases back into the engine's inlet air. It
doesn't take much. EGR accounts for less than 10 percent of the total
air/fuel mixture but even this small amount of non-flammable stuff is
enough to quench the flame somewhat. When everything is on the money,
the EGR lowers combustion temperatures to just under the 2500°F
bogey.

From here
http://www.aces.edu/~parmega/efi/egr.txt

Also found this
http://www.nazigassings.com/PDFs/zheng2003.pdf

What it basically states, is that at idle or low engine load, a diesel will run on a very, very lean mixture.
(take your foot off the gas to slow and it'll inject virtually no fuel yet suck in massive amounts of air).
This lean mixture will increase combustion temps as a lean mixture burns much hotter.
The opposite occurs when the gas pedal is clogged, the injectors fire in lots of fuel and produces a rich, cooler mixture.

This is where the EGR comes in, to reduce the temps on the lean burn at low load/engine speed, the valve lets exhaust gas into the combustion chambers which reduce the burn temp.
 
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