I wouldn't call it a epidemic but I have seen issue of injector pump timing across all the major brands. The problem is more or so isolated to specific models within each brand. The issue is common on units that are equipped with the older tier I engines that were basically modified to meet tier II emission. They were able to meet tier II specs by doing a few things like adjusting the injection pump timing and internal breather systems, but these older engines can only be taken so far. With the increasing emission standards the engine manufactures are going to have to develop newer style engines with more efficient combustion chamber and electronic injection system which cost major money to develop.
If you look at the problem as it related to the different brands one thing becomes apparent. The problem is mostly related to the economy or low cost units. Now, I'm not trying to say that these are junk. Dollar for Dollar most of these units offer you the best value for your buying dollar, but the manufactures of this units rely on older tried and true technology (low cost) to give you that savings. This is nothing new it's what Kubota and others have been doing for years and now both Deere and New Holland have gotten into the game.
The 03 series Deere. TTA series NH and the Mahindra's have all experienced issues with injection pump timing. All these tractors are built in India within a few hundred miles of one another and all use proven, but older technology in order to give you, the customer a reliable and economical tractor.
No manufacturer knowingly wants to sale a customer a tractor that's not right, but sometimes things may slip through a quality check or develop after a few hours of uses. This is where the dealer comes into play with fast, reliable and friendly service.
Let's face it... the compact tractor market is changing and a large part of that new market is demanding a more economical product and any one wanting a place at the table better offer what they demand.
The manufactures are going to have to start modernizing some of the older parts and when they do the price will currently start to go up also, but at the rate the "upper end" units are rising they will always offer a economical option.