XANTIA HDi RUNNING ROUGH

[Rhothgar]

That what I was thinking Jim.

His emissions are very bad at the moment with all the smoke hence the suggestion.

No post-heat will not result in that much smoke though Roger...

Easy to check, just look for 12V on them just after a cold-start...

Of course, you’ve seen it in the flesh so have a better idea. Thanks for clarification.

[CitroJim]

Yep, it smokes like a Deltic Roger...

[CitroJim]

There's something nagging at the back of my mind...

When we ran the engine with the hose to the inlet manifold disconnected (i.e. manifold open to atmosphere) and the EGR active (EGR valve open) we could see smoke puff out of the inlet manifold.

Logically, I'd have thought there would have been enough suck available - knowing diesels can cause serious injury if a hand gets too near an air intake - to suck smoke straight in and not allow any to escape to atmosphere...

As I say, just a nagging thought and possibly pointing to valve damage/leakage...

A diesel leak-down test will be needed to confirm and put this thought to bed, one way or another.

[Rhothgar]

That’s a good point Jim.

By diesel leak down yesterday, do you mean the test where you measure leak-off otherwise I am not sure what a leak-down test is.

If you mean the test where you hang the bottles up and measure the amount of diesel returning to the cylinders, what would you expect to see and why? This sounds fascinating.


I guess you’re thinking along the lines of if a valve is damaged then diesel will leak past a damaged exhaust valve rather than being compressed?

EDIT: NO NEED TO REPLY.
I’ve just found something very interesting. I’d NEVER heard of a leak-down test. Saves stripping the engine unnecessarily.

[CitroJim]

EDIT: NO NEED TO REPLY.
I’ve just found something very interesting. I’d NEVER heard of a leak-down test. Saves stripping the engine unnecessarily.

I was just about to reply Roger and you saved me a job

[moizeau]

Not so long ago I did one on my Zeph11 when I noticed a cool downpipe. (That's another test to perform actually with in infrared temp gun on each downpipe.) I been having a pop on cyl 2 after after stripping the carbs 3 times, which is quite a job, I measured the temps. No.2 was a lot cooler the the other 3. Did a compression test and it was a lot lower. Didn't do a leakdown test properly, as in 2 guages to see jow much each cylinder loses over a given time period, more like get No. 2 to TDC and inject compressed air into the sparkplug hol using an improvised tool and listen to where it was coming out. carb, exhaust or oil filler. Twas exhaust. Had to go down 6 shim sizes to get into perfect condition. Goes like the clappers now......well it would really, it's gained 1/2 a cylinder.

[Skull]

Well the weather and my enthusiasm have slowed this job down, all I’ve done is loosened off the glow plugs and ordered a diesel compression tester to try and get to the bottom of the problem….

I keep going over the same thing in my head how the car drove onto my driveway with a leaking core plug which was changed easily enough and when the engine was re-started ran rough, also how the symptoms seem to have changed from cylinder to cylinder…initially my mot mechanic demonstrated how No. 4 would stall the engine when removing the electrical plug off the injector, now when we do that it makes no difference to the engine’s performance. Confused-dot-com…. Despite the symptoms and testing I don’t think it’s a mechanical issue ….

Anyway once the compression tester arrives (next weekend) I will see what it shows…I know you’re supposed to do them at normal operating temperature but that will probably have to be ignored as there’s a lot in the way although I might try even if I have to re-warm between cylinders…..

Not so long ago I did one on my Zeph11 when I noticed a cool downpipe. (That's another test to perform actually with in infrared temp gun on each downpipe.)

Funnily enough we spoke about that when Jim & Mick visited for a brain storming session, how if you had a 4 branch exhaust it would be so much easier to find which cylinder wasn’t behaving.

[Rhothgar]

Well the weather and my enthusiasm have slowed this job down, all I’ve done is loosened off the glow plugs and ordered a diesel compression tester to try and get to the bottom of the problem….

I keep going over the same thing in my head how the car drove onto my driveway with a leaking core plug which was changed easily enough and when the engine was re-started ran rough, also how the symptoms seem to have changed from cylinder to cylinder…initially my mot mechanic demonstrated how No. 4 would stall the engine when removing the electrical plug off the injector, now when we do that it makes no difference to the engine’s performance. Confused-dot-com…. Despite the symptoms and testing I don’t think it’s a mechanical issue ….

Anyway once the compression tester arrives (next weekend) I will see what it shows…I know you’re supposed to do them at normal operating temperature but that will probably have to be ignored as there’s a lot in the way although I might try even if I have to re-warm between cylinders…..

Not so long ago I did one on my Zeph11 when I noticed a cool downpipe. (That's another test to perform actually with in infrared temp gun on each downpipe.)

Funnily enough we spoke about that when Jim & Mick visited for a brain storming session, how if you had a 4 branch exhaust it would be so much easier to find which cylinder wasn’t behaving.

It is so easy for enthusiasm to drop off as we approach colder weather.

This is really useful that you have recorded your actions again and certainly not a bad thing that you have said you keep going over it in your head! I would too.

What strikes me is that the issues started after the core plug change. You say it was simple but was it? Because, at some point, you were worried that you have shorted things out! Can you expand on this please in basic terms. How did the core plug change go and what actually happened? Did you drain down the system beforehand? I guess not but let's take the guessing out of the equation. Did water leak or spray onto any areas?

Sometimes, things happen coincidentally which leads us down the wrong paths and there is no rhyme or reason as to why an entirely unrelated fault occurs. Is that the case here or have you forgotten to include some details? More often than not, when we have our heads under the bonnet we are not necessarily thinking or making mental notes of what we are actually doing.

I watch Pine Hollow Auto Diagnostics videos on YouTube and from his detailed diagnosis on all things electrical it becomes really easy to see how a fault can lie dormant especially in crusty wiring (and therefore especially on our old cars) such that even moving part of a loom inadvertently out of the way whilst we do something could potentially cause a fault to develop.

He has a couple of good videos, one of which is called "Pt1 Ford kills battery" and also Part 2 to that video. Whilst not related to your issue, it is well worth 70 minutes of anyone's idle time watching to understand some of the concepts he uses for troubleshooting. In these particular videos, he goes on about how you can accidentally fix a fault by wiggling wires and how that isn't a fix because if you're not looking at live data you then fix a fault which then becomes a temporary fix because you haven't actually identified it and investigated it further and repaired it properly.

After watching those videos, I found the route of a B952 FM2 Aerial short to ground on Sylv's Peugeot within 30 minutes. Totally unrelated but conceptually the same.

When you say your MOT mechanic initially demonstrated removing No. 4 injector wire would stall the engine and now it doesn't. When did he actually do that? Presumably some time before this issue arose or were you driving back from the MOT after he did that and then it ran rough the following day? Or did your MOT mechanic come around to yours to try and help? This information could be crucial. It's certainly may be important. It's interesting and may be worth extra investigation.

I wouldn't worry too much about engine being warm for compression testing. You'll simply be looking for a large imbalance on one cylinder.

[Rhothgar]

I don't wish to panic you but copy and paste this into Google.

"can unplugging an injector wire on a common rail bosch edc15c2 whilst the engine is running damage the ECU"

Take it with a pinch of salt but it is worth investigating in terms of whether it is a piezo injector on your engine (I assume yours will be inductive/solenoid injectors because they run at 78 volts like mine no doubt).

I am sure others may well have their views on this but I thought it sounded a pretty stupid thing to do hence my search. I've also texted my diagnostics mate who is on holiday for a month now to see if anything can be gleaned from his experiences and thoughts.

I'd be interested to know if the engine was already running rough prior to the MOT mechanic pulling the connector wire off? Maybe it was running rough but also maybe it caused an additional issue. What a pain if that turns out to be the case.

One way to check that is to swap out the ECU, immo and key with a known good set that someone might just have lying around for you to borrow. There must be someone on the forum with kit. I have a feeling I have a spare set lying around somewhere.

From that article, it would make some if one transistor within the ECU (driving no. 4) has been affected.

I am going away for 3 weeks over Xmas. I am not sure I would want to loan my ECU, immo and key out in case it was to get damaged in the process of some damage that may be less apparent on your vehicle. Perhaps Jim will have thoughts on this. I would happily loan it out to you for ruling out the above providing I have some fallback position ie replacement ecu, immo and key. This assumes you have the single connector 88 pin ECU.

EDIT:

My diagnostic mate replied:-

"As stupid as stupid can be"

"He probably pulled it off to show it wasn't contributing if that was the case it was probably already running rough. Injectors can stick open and then over rev engine".

From that, he is unclear on why your mechanic would do that. Reading between the lines, he might well be saying that the roughness is caused by over-compensation of the ECU trying to correct an injector that may well now be jammed open in a certain position?

[Rhothgar]

This is also worth reading. It states that inductor/solenoid injectors are unlikely to be damaged but...

https://www.picoauto.com/support/viewtopic.php?t=6763

Picotech is an excellent reference source and it is amazing what can be diagnosed with their kit without stripping things down.

[Skull]

Thanks for all that motivation Rothgar I also don't 'need' to use the car at the moment ...

I will attempt to re-iterate the sequence in a brief re-cap, it's all disclosed in the thread, however unbelievable it appears to be:

Engine running fine ....
Engine cut out - restarted after a couple of tries over a couple of minutes (suspect coolant sprayed on Fuel Pressure Sensor)
A few days later .... engine cut out again, wife said she nearly crashed...I travelled down and engine started, ran nice and drove home about 1.5 miles.
Parked on driveway and inspected, while wife reved engine and leak from core plug revealled itself. No ther faults apparant at this stage.
Changed core plug (injector loom and fuel rail removed - I have done one before on this engine)
Added about 2 litres of coolant and restarted engine.
Whilst warming/bleeding coolant through, the engine was running rough, smoking and wouldn't rev beyond 3,000 rpm.
Engine seemed to take ages to warm up and must have had a small airlock as the coolant temperature/level light came on with STOP light flashing.
I had expected the radiator fans to be on at this stage (My error as I now believe it was just an airlock).
However at the time I thought it was an error with the radiator fans. Hence why I tested the fans by shorting out the Coolant Tempature Sensor.
Fan motors were both working correctly.
Engine still running rough/smoking.
Checked engine timing at this stage as I couldn't see any other reason for rough running.
Engine timing out by what amounted to 1 tooth.
Re-timed engine expecting some improvement.
Engine still running rough/smoking.
Booked a diagnostics session at my local MoT garage.
Diagnosed a suspect No. 4 injector.
Bought 2 second-hand injectors to try. No improvement (one subsequently appears faulty)
Sent No. 1 and No. 4 injector for testing - both failed.
Re-fitted my 'best' injector - no improvement.
Opted to exchange the non-running Ebay injector for a new injector with the view of expecting improvement.
Fitted new injector along with my 'best' tested injector.
No improvement.
Mick and Jim arrived for a 4 hour session of Lexia/diagnostics, despite all our combined efforts we couldn't fix it on the day.
As suggested checked Woodruff Key intact (suspected cam/valve timing issue on No. 4 cylinder)
Now awaiting a compression test ...
Last 420 miles I've spent £436.30 so about a quid a mile

[Rhothgar]

WOW! That’s some investment which is why we want to be sure to test and not guess.

Still some assumptions in there eg:-

coolant spraying on the fuel pressure sensor.
I suspect you thought this because coolant system was under pressure when wife called to say there was an issue?

Without being in front of mine, I cannot recall if injector wiring is obvious. Reason I ask is are you 100% sure that they each went back on the corrector injector? Not sure if this would have an effect but Lexia session would have thrown up codes. I’ll check that in a minute.

After the suspected FPS issue (not sure it would actually short the sensor (this is testable with an oscilloscope) did it run fine again BEFORE the coolant top up and fuel rail removal.

Was engine temp within limits when you got home and had the wife rev it?

Engine retiming!
It had been running fine since 2021 cambelt change but you found it to be out. You intoally wrote 2001 cambelt change. Can you confirm when it was done and who did it? If you did it then surely it ran fine when you initially changed it.

When you retired recently you didn’t happen to do a stupid thing that I did last year and rotate the cambelt tensioner in the WRONG direction? Worth checking to see if the tension is still fine.

No use going over old ground at this stage as you’ll have tested compression soon enough. Only if that doesn’t provide some answers is it worth revisiting what I have said.

Much of this has probably already been checked by Jim maybe.

[Rhothgar]

I’m sure this has been clarified but the Lexia states Injector 1 and you refer to injector 4?

Looking at that live data, the flow is too high at 21mm3/cp at 739rpm. Mine was 12mm3/cp at 830rpm.

My diagnostic mate suggested you avail yourself of some noid lights. I’d never heard of them but they will test the circuit. About £20 online.

Look up scannerdanner noid lights on YouTube. He has a video which starts Chapter 18. It is a class it sounds as though he is running and he makes some comments about noid lights in there. They appear to test the circuitry.

Judging by what I am seeing in that Lexia session , the harness resistance is of concern. I would be VERY careful checking all your injector loom for signs of breakdown. It’s obviously hot on that region and the insulation on Citroen wiring is crap to be blunt. You may well find an issue there. Of course, noid lights might flag the troublesome part of the loom and narrow it down for you.

Good luck!

[Skull]

Agreed Rothgar there are still some assumptions ....

There was no abnormal coolant pressure then or now.

My wife has a job remembering how to lift the bonnet even after 15 years of driving Xantia's so ....car works > car broke is her input.

Injector wiring harness is contained in a plastic frame so only goes back one way.

Yes engine was running fine (even though at some stage the timing had jumped a tooth)

Engine temperature was fine - all engine cut-outs were within 2 miles of a cold start around town. Engine only needed 2-2.5 Litres top up after changing the core plug in the cylinder head.

Yes I changed the belt myself in 2021 and used Jim's SEEMS meter for accuracy. Tension was fine on re-timimg but IF this current issue is resolved I will be replacing the tensioner as it is whinning a little now when higher tension is applied.

[Skull]

I’m sure this has been clarified but the Lexia states Injector 1 and you refer to injector 4?

Yes Injector No. 1 in the Lexia photo was disconnected in the initial photo.

Cheers ...