BX

You can always have an aftermarket tachometer sold in many car parts stores. However, these are additional units you have to place somewhere on the dashboard; not a nice thing to do if you want to keep the looks of your car as original as you can. But if you replace your instrument panel unit with one having a tachometer, you can have the same layout BXs with higher trim levels originally had.

You should start the troubleshooting at the sensor in the engine. Use a voltmeter in AC measurement position and observe the voltage at the two terminals of the sensor as you rev the engine up (have either an assistant or a long meter probe). If you measure absolutely nothing, the sensor is suspect (although you can check it with an oscilloscope if you can find one somewhere).

Traditionally, stroboscopes were built with xenon flashlights such as those used in photographic flashguns. However, these flashlights require a 400-600 V voltage and even more for igniting them. Needless to say, electric shocks of such voltages are often lethal. Unless you have experience in building such high voltage circuits (including proper insulation) and also have measuring equipment to help with the process, you shouldn't even think of building one.

Citroën originally fitted Champion spark plugs but specifies Eyquem and sometimes Bosch equivalents as well. The best choice would be the first one, however, there is a major problem: Champion and Bosch plugs are manufactured at many plants all around the world. Although the technology is supposed to be the same everywhere, there are significant differences between the quality of those plugs. Those manufactured in the Belgian and British factories of Champion and in German plants of Bosch are excellent but those from other countries are average or often quite bad.

Clean combustion resulting in clean oil (assuming it has the proper grade, not some cheap concoction) is essential not only for the engine but for the turbo as well. Most people are not aware that a turbo can be--and actually should be--cleaned every 150,000 km or so. This procedure will make it last forever.

Most people are not aware that the main reason a diesel engine wears out is improper combustion, usually caused by worn out injectors, improper timing, or simply lack of air (influenced by several factors, one of which may simply be a dirty air filter). Anything which produces soot (eg. particulates), including the "black smoke" effect, results in particulates ending up in the engine oil. This soot then accumulates in areas where oil flow is low, like behind the piston rings. As the deposits grow, the ring is being forced outwards.

A lot of things happen at the moment the fuel is injected. If the fuel was somehow perfectly microscopically atomised on injection, it would not self-ignite at all. It would have trouble igniting even with a spark plug. Ignition needs a richer fuel-air mixture, and this is locally provided by the start of the injection being full of larger drops of fuel, because it occurs at a lower than maximum pump pressure (about 2-3 times lower). The evaporation of components from the fuel as it enters the hot compressed air is what makes it ignite.

Diesels are taken for granted in 99% of all cases--the truth is, most of them can take an incredible amount of "just driving", but the neglected maintenance results in slow decay. However, even engines treated extremely poorly can easily run 100k miles or more.

Most people come to a diesel from a gasoline car, and apart from the obvious differences, they do not realise how different the engine really is. Although it is very similar mechanically, the basic pricinples are very different.