XUD Xsara, strange misfire and loss of power

[johnny625]

The alternator was taken out of the car. The alternator itself tested fine electrically and mechanically but the brushes on the voltage regulator were far too gone and sticky in their travel probably not making good enough contact with the slip rings. The whole regulator will be replaced and I am confident that the electrical issue will be fixed at least.

Also I had a second opinion on the injection pump. It seems that the pump might only require a readjustment of the max fuel and the boost compensation spring and replacement of the diaphragm there. To my knowledge neither the max fuel nor the boost compensator have ever been fiddled around with and the max fuel plastic bung on the front of the pump doesn't look that it has been ever unscrewed.

In more detail the old guy that gave me the second opinion (who btw is respected for being very knowledgeable on diesels around here) thinks that some small rod which resides behind the boost compensator might be sticking in its travel and causing the engine to have horrendously wrong fueling in both idle and when the go pedal is pressed down.

He also remembered that he had a Ford Mondeo TD with a Lucas injection pump that had very similar symptoms to my Xsara and he is confident that he can fix the car. After I put the alternator back in the Xsara is off to his place and I just hope for the best.


Otherwise the car is fully serviced and I changed the oil about 5000 kilometers back together with the air and the fuel filter. The cambelt and the aux belt and all of the tensioners were also done less than 9000 kilometers ago.

Thank you for your insight everyone.

[CitroJim]

In more detail the old guy that gave me the second opinion (who btw is respected for being very knowledgeable on diesels around here) thinks that some small rod which resides behind the boost compensator might be sticking in its travel and causing the engine to have horrendously wrong fueling in both idle and when the go pedal is pressed down.

Excellent Do let us know if that fixes the problem

[johnny625]

Finally good news.

The alternator voltage regulator sorted the voltage variation. It still drops down but not nearly to the previous level.

Today I took the car to the guy that promised he will fix it. Actually turns out he has plenty of equipment in his diesel specialist shop. After less then two hours of tinkering with the boost compensator and the max fuel screw and advancing the injection pump timing slightly the car was back to pretty much normal. It still however had a tendency for rough running after being revved up and the engine rpm's going back to idle. It turned out that the banjo type of a bolt thing the screws the return diesel line into the pump was blocked somewhat.

After it was cleaned and unblocked I had a chance to 'test drive' my car and tell them how does it feels..and the result is...the bloody car has never went so well. The throttle response is amazing and I am convinced that he gave the car a slight 'stage 1' tune while tinkering with the pump. It smokes black noticeably if I boot it off boost and I need to add throttle progressively to avoid excessive smoking. Nevertheless I am happy with how things are right now.

Thank you for your help everyone

Off to have a night drive with my Xsara

[elma]

Result! That does sound like it had a bit of a tune up, lucky you.

[CitroJim]

Excellent news Pleased it is now all resolved...

[ekjdm14]

Fantastic news indeed, perhaps in working on the diaphragm he has turned up the overfuelling a little & could stand a bit of adjustment to the wastegate if it's the threaded type of actuator.

Having said that, if it's going well enough as it is & emissions are acceptable if/whenever you have to have them tested then I'd call it a win.

[johnny625]

I would love to adjust the turbo mate though lifting the car high enough (at least in a safe manner) so I can get under it and access it is pretty much impossible with the tools I have. I guess it will have to be done on a pit or when the car is on a lift. I do think that the car runs a Garret T2 turbo with an external threaded rod adjustment.

I also noticed that when on boost, no matter how hard I boot it I can only see a slight grayish haze in the side mirror. However if I do it off boost the smoke is much thicker and blacker in color but can be avoided nearly completely by taking it easy with the gas pedal until the boost kicks in. The car goes rather well and yesterday I was able to do a 0-100 kmh run and did in about 12.2 seconds without even trying too much which is a bit faster than stock (12.8).

During annual car registration checks the emissions are measured but only cars with the dirtiest of diesel exhausts fail. Most cars seem to pass the test easily.

I guess it will surprise you that the old diesel guy that fixed the car recommended putting about 0.5 % of two stroke oil in the tank. This translates in about 250 milliliters per full tank of diesel in the Xsara. In his words 'it can't do harm on these engines'. Apparently it did lubricate the internals of the pump better than modern diesel that has almost no sulfur in it thus contributing to the longevity of the pump. Well at least according to him.

[white exec]

I have heard about 2-stroke being added to basic diesel to improve it. It not only adds some lubrication, but also is supposed to act as a cetane improver. I tried it a few years ago on both our XM and Toyota D4D 2.0, and it did pretty much the same as regular products like Wynn's and Millers, but more expensively, and did not mix so easily.
If you use good quality diesel, you probably won't notice any difference. On cheap or supermarket stuff, you might. Harmless enough to try......just make sure it's well mixed in.

[CitroJim]

I have heard about 2-stroke being added to basic diesel to improve it.

Two-stroke will make it smell nicer too Chris

Whenever I get a whiff of a two-stroke it takes me right back to the happy days I ran big two-stroke motorbikes and raced karts...

The karts smelt even nicer as we used Castrol R in those

[Paul-R]

The karts smelt even nicer as we used Castrol R in those

Back in the day, many boy racers in their Minis used to put a couple of shots of R into their petrol to give that "Aaaaah" smell as they went past.

[CitroJim]

The karts smelt even nicer as we used Castrol R in those

Back in the day, many boy racers in their Minis used to put a couple of shots of R into their petrol to give that "Aaaaah" smell as they went past.

They still do around this way Paul, I get a whiff of it from all sorts of vehicles (both 2 and 4-wheeled) being piloted by youngsters...

It's a bit like the smell of 'funny fags' - once whiffed, never forgotten...

What those who use it for effect don't realise is running too much Castrol R is not good for the engine... It leaves very gummy residues and makes very hard carbon...

We used to strip and rebuild our kart engines after every race meeting and had to decoke the exhausts using oxy-acetelyne!

Still, when you're a lad such considerations are inconsequential - dad will resolve all

[Paul-R]

When Mobil 1 oil first came out (the first synthetic engine oil) that was also reputed to give a Cazzy R whiff to the exhaust. Didn't seem to to me though.

[CitroJim]

When Mobil 1 oil first came out (the first synthetic engine oil) that was also reputed to give a Cazzy R whiff to the exhaust. Didn't seem to to me though.

A new one on me... Possibly an early sales line Paul... More, perhaps, to compare it's lubricating properties with the old legend...

Truth is, Castrol R is now well and truly outclassed by modern synthetics and is only likely still made for historic engines; a bit like the small residual market for straight mineral oil...

[Paul-R]

Am I right in thinking that R is still the oil of choice for engines that run on alcohol?

[moizeau]

When I was working at Norton we used Rotella generally but every now and then we got some Castrol TTS, that was almost addictive it was so nice. Regarding mineral 2 stroke oil, did anyone know that the expensive Stihl oil is mineral even though it's twice the price of a good semi-synthetic. Obviously just paying for the name!