Citroen Xsara emissions problem...

jimgoose

How-do squires.

Been bating my head off a concrete post with this one. In short, 1999 Xsara 1.4i with just under 100k on it. NCT test, both high and low idle, Lambda of about 1.04, high CO and high (but not failing - just) HC. This says to me that it's not burning properly for some reason.

Thus far, Dipetane in the fuel, followed by a couple of "Italian tune-ups". Cat-converter, Lambda sensor and coolant temperature sensor swapped out. Full intake and exhaust manifold vacuum leak tests. New plugs. Air-filter good.

The thing doesn't burn a drop of oil, goes like a (small) train, has full compression and generally behaves impeccably. After much pricking about I'm left with the crackpot theory that the injector pulse timing is out for some bizarre reason. I'm thinking a crankshaft sensor running ten degrees out or so could cause this, but I don't think a Hall-effect sensor ever fails that way.

The crappy OE Sagem coilpack was replaced a few years ago, and I'm not sure right now whether another Sagem unit went into it. I hear a bad coilpack can upset an already-delicate (Sagem) ECU in them and cause all kinds of psychological issues.

Before I throw any more parts at the wretched little French bastard, any advice forthcoming would be most welcome!

EDIT: I should add, fuel consumption is quite heavy for that car as well.

bear1

Was the cat and lambda brand new or second hand? I mean was the CAT spurious or genuine?
I see you haven't mentioned the fuel filter, if this is old/clogged up then you could get poor fuel economy.
How is the exhaust? Any splits can cause issues I believe with the lambda.
Also maybe you have an injector spray pattern?

jimgoose

bear1 wrote: »

Was the cat and lambda brand new or second hand? I mean was the CAT spurious or genuine?
I see you haven't mentioned the fuel filter, if this is old/clogged up then you could get poor fuel economy.
How is the exhaust? Any splits can cause issues I believe with the lambda.
Also maybe you have an injector spray pattern?

Two cats involved, one about eight months old and the other brand-new. Spurious, but different makes. The Lambda sensor used was out-of-the-box. Exhaust is good, fuel-filter good.

Excuse me for being a bit thick, but what do you mean by "maybe you have an injector spray pattern"??

bear1

jimgoose wrote: »

Two cats involved, one about eight months old and the other brand-new. Spurious, but different makes. The Lambda sensor used was out-of-the-box. Exhaust is good, fuel-filter good.

Excuse me for being a bit thick, but what do you mean by "maybe you have an injector spray pattern"??

Each injector has to have a particular spray pattern:

https://www.youtube.com/watch?v=fDFgiLrEX1o

A bit like this video.
If you injectors are dirty or failing then the pattern changes and doesn't fire the correct amount of fuel. So you then start to have an emissions problem as it can start to burn lean.
I believe the spurious ones can cause problems and it's generally recommended to buy the original ones.
Does the car get to normal operating temp?

jimgoose

bear1 wrote: »

Each injector has to have a particular spray pattern:

https://www.youtube.com/watch?v=fDFgiLrEX1o

A bit like this video.
If you injectors are dirty or failing then the pattern changes and doesn't fire the correct amount of fuel. So you then start to have an emissions problem as it can start to burn lean.
I believe the spurious ones can cause problems and it's generally recommended to buy the original ones.
Does the car get to normal operating temp?

Oh yes. The only thing about the way it runs is, on cold-start it sort of feels like it's not getting proper cold enrichment, and the idle is slightly lumpy at all temperatures.

The quare thing is, despite the ludicrously high Lambda reading the CO and HC levels would, on the face of it, appear to contradict that.

bear1

jimgoose wrote: »

Oh yes. The only thing about the way it runs is, on cold-start it sort of feels like it's not getting proper cold enrichment, and the idle is slightly lumpy at all temperatures.

The quare thing is, despite the ludicrously high Lambda reading the CO and HC levels would, on the face of it, appear to contradict that.

Hmm, this could well be your culprit. One of the first things that springs to mind is the MAF (Mass Airflow Meter). It could be dirty for example.
The MAF and throttle body may need a good clean.
I wonder if your temperature sensor is failing as well?
After looking a bit more on the net a few people are saying that the Xsara also suffers from a dirty MAP problem which can cause high emissions.

jimgoose

bear1 wrote: »

Hmm, this could well be your culprit. One of the first things that springs to mind is the MAF (Mass Airflow Meter). It could be dirty for example.
The MAF and throttle body may need a good clean.
I wonder if your temperature sensor is failing as well?
After looking a bit more on the net a few people are saying that the Xsara also suffers from a dirty MAP problem which can cause high emissions.

Mmm. Seemingly it's a MAP/IAT combo unit. I'll check it out. Thanks for the second braaane, Bear.

bear1

No worries, let me know how you get on so that I can be happy that I'm useful for something

jimgoose

bear1 wrote: »

No worries, let me know how you get on so that I can be happy that I'm useful for something

Will do squire. It hadn't really occurred to me that a wobbly intake sensor could result in this particular peculiar set of emissions readings, but strange things happen in these little French bastards. Strange, terrible, unfathomable things! :pac:

jimgoose

Well that, at best, improved things maybe very slightly but not anything like enough. Now the thing is reporting P0130 - O2 sensor circuit. Gods-dammit!!

bear1

I guess the only thing left is to swap out the o2 sensor. Seems like you're having fun with it

jimgoose

bear1 wrote: »

I guess the only thing left is to swap out the o2 sensor. Seems like you're having fun with it

Done already. I'm going to reset the ECU in the morning, make it "re-learn" the car, as 'twere. Failing that, I'll have to shove a replacement ECU in there. Gaaaaaggh!!

jimgoose

This thing is still making my head pound. We've abandoned the ECU theory as highly unlikely, there's a good Bosch unit in it as it turns out, not Sagem. The coolant temperature sensor and MAP have been changed out, being cheap enough parts. I swapped out the fuel rail and injectors for a fresh used unit from a breakers, on the off-chance that a spray-pattern issue as suggested by Bear was at the root of it. The throttle "crispness" and slightly lumpy idle improved somewhat, but emissions are still arseways and it failed again yesterday.

So this week I shaved my head and journeyed into the high Tibetan Himalayas to visit with The Master. I found him in his cave sitting in the lotus position, breathing:

"Enter, Grasshopper. There are many Paths. Which one brings you here today?"

"Umm, emissions all ballacksed about, has me baffled!"

"At the heart of all things is harmony. Void. The peaceful, undisturbed and imperturbable core around which the maelstrom of the World whirls. This applies to an engine just as to everything else. This truly is the Tao. And that fcukan thing is running like a bag a' hammers."


The Legend continues...

jimgoose

There is a conclusion to this. A lesser person would have gone quite window-lickingly insane a long time ago, but I have great faith and tenacity, possibly born of intellectual disability. Anyway...

Much fluting about ensued, including cleaning out the fuel tank, in which small traces of water were found, re-timing the engine, and verifying all the sensor I/O with an oscilloscope. All to no avail. The old paper-against-the-tailpipe trick gave no indication of a burnt exhaust valve or anything like that. Temporarily blanking the PCV made no difference either, and it's a dirty swine on those engines.

Then I got a notion, inspired by a conversation I had with a chap I know who has a lot of experience with oddball old Citroens. I got a new idle-control valve, which was about EUR20 from a supplier in the UK, and set about dismantling and cleaning the throttle body. FYI, the Xsara's throttle-body has four electrical connections to it - the ICV, throttle position sensor, a heating element, and the intake air-temperature sensor. While I'm at it, the Xsara also uses no less than three coolant temperature sensors - the aircon controller sensor, which also switches the cooling fan on and off, the dash temp-gauge sender, and the ECU temperature sensor, being the one that actually affects fuelling. The idle-circuit area of the TB was in shocking condition, but with toothbrush, Swarfega Jizer and patience that would have made a Shaolin monk blush, it wound up like this:

Throttle body - butterfly

Throttle body - ICV side

The round, shiny recess at the top-left of the second photo is where the ICV lives. Here it is, the old one on top, the new on the bottom:

Old and new ICVs

Note the wear on the "needle" and general decrepitude of the old one. It was also quite wobbly and noisy in operation. After reassembly and a bit of a gallop around the place, the car seemed to be running a little better, but a quick emissions test round the corner revealed no change in the situation. With a mighty roar of "There is FUCK-ALL wrong with that engine, gods-DAMMIT!!!", my friend the mechanic and I reasoned that the cat must be gone again, possibly at least partly because of the state of the ICV and ICV area of the throttle body. It turned out that two cheap-and-not-so-cheerful Klarius units had gone into it, and died. I had no idea the issue with crappy, poorly-built catalytic converters was as bad as this.

After pricing an OEM cat at a Citroen main dealer at around EUR650, Mrs. Goose hit the Web and found a used cat from a 2001 Peugeot 306 (same PSV part number) at a large dismantlers in Ballina for EUR85 including postage, which arrived the following day. This was duly fitted, and lo, observe the hot low-idle readout:

Gas analysis - low idle

...and the hot high-idle, around 3,500 RPM:

Gas analysis - high idle

Thing a' beauty. That's better than new.

Now, the credits. Many thanks to Mrs. Goose, who's patience, endless mugs a' Tae and actually sourcing the crucial part in the heel of the hunt made all this fcukacting possible. Thanks to Damien Murphy of QuickStop Tyres and Service, Model Farm Road, Cork, for his gas-analyser, gumption and patience. Thanks to DDM Technik in the UK and their eBay store, purveyors of the finest auto parts at reasonable prices, and who's customer service is second to none. To none that is, except Dempsey's Car and Van Spares, Ballina, who supply top-quality kit, supply it fairly lively, and stand over their operation to the hilt.

This didn't half turn into the legendary "Story Twenty-Two Verses Long", but I hope my chronicles will be of some use to someone facing similar difficulties. Never listen to gowls telling you the "D'Injin is Gone, like!!" when they don't actually understand what is happening. Stay the patient course, stick to the intellectual bulldozer of Scientific Method, and keep repeating to yourself "The little bastard is perfectly simple, I will not be defeated by a dumb machine!!" And be very, very wary of cheap spurious catalytic converters. It seems to me that many of them are simply not equal to the job, particularly on older cars.

Happy wrenching! :cool:

bear1

No credit to the only eejit who responded to this thread :P
What a waste

jimgoose

bear1 wrote: »

No credit to the only eejit who responded to this thread :P
What a waste

Oh that was some nice thinking out of you with the injectors, Bear.

bear1

Oh you...

jimgoose

Where are my sodding attachments gone?!?

jimgoose

NCT until November 2016. Low idle CO 0.01% HC 58ppm, High idle CO 0.01% HC 38ppm. Lambda 1.00. Bish-bash-bosh.

Ded_Zebra

Well done for sticking at it and posting all your findings. Even if no one was much help to you I'm sure it'll help someone in the future


A good read at the very least! :P