Engine Performance Problems

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Problems in modern Engines.

These days car engines (Petrol and Diesel) are so Hi-Tech and complicated, the average motorist cannot carry out under-bonnet repairs.  Even garages are finding it difficult to keep up with technology.  Car engines are "managed" electronically so "tuning" a car is a thing of the past.  If a car has a starting problem, a misfire or a loss of power, you cannot tune-it-away like we used to.     So what can we do??


Lets think about that for a moment and consider the facts!

Electronic engine management is great from many points of view: -

  • It helps keep your vehicle running economically.
  • It helps to reduce vehicle emissions to lower levels than ever before.
  • It drives vehicle reliability to far higher levels.
  • It stops unskilled hands from messing up important settings.

The problem is, to manage a modern engine, within the very tight limits now set by governments, an engine management system relies on accurate readings from many sensors and actuators around the engine and the rest of the vehicle.  Here are some examples: -

  1. Lamda (Oxygen) sensors [In the exhaust before and after the catalyst]
  2. EGR Valve [Re-cycles a percentage of exhaust gas back into the induction side of the engine]
  3. Throttle Body [Either mechanically or electronically controls engine speed/power]
  4. Fuel Injector [Can be either in the intake manifold close to the inlet valves or, as is now more common, actually in the cylinder, just like diesels!]

Now this is fine, whilst these sensors and actuators are clean, accurate and free to move without sticking  !

What actually happens is, as you drive your car, contamination starts to build-up over time eventually causing a problem.  What kind of problem?  Well lets have a look: -

  • Lamda Sensor:  Probably the most important sensor in your engine.  These sensors sit in the exhaust, close to the engine, continuously monitoring the oxygen content remaining in the exhaust.  These sensors are based on a porous porcelain body allowing exhaust gases to affect a sensor that then re-tunes the engine fueling, and this happens many times a second.  The porous quality of the sensor body can become contaminated, reducing the sensitivity of the sensor so that in extreme cases, the sensor fails to sense at all!!!   ENGINE MANAGEMENT LIGHT COMES ON!    POOR PERFORMANCE!!    POOR ECONOMY!!!    DIRTY EXHAUST EMISSIONS!!!!     THIS CAN EVEN LEAD TO PREMATURE CATALYST FAILURE  ££££££'S


  • EGR Valve:  This component give more trouble than most as it sits between the exhaust and the induction systems in a very hostile environment.  The reason its there is to recycle a percentage of the foul exhaust gases back into the induction side, to quench combustion temperatures.   Sounds mad doesn't it!!  The fact is that, at very high combustion temperatures, higher levels of NOX are produced and this is highly undesirable!!   To reduce NOX emissions, we bung some foul exhaust gases back into the cylinder to mess up the combustion process and reduce the temperature.  Crazy but true!!   The real problem is the this EGR valve gets contaminated and sticks, messing up how the engine management is able to control it.   ENGINE MANAGEMENT LIGHT ON!   POOR PERFORMANCE!!   DISGUSTINGLY BLACK AND SMOKY EXHAUST!!!!                                                                                                                     Ever followed a car or van belching out black smoke??   Chances are it was a sticking or faulty EGR Valve!!

  • Throttle Body:  Used to be controlled directly by the driver via a cable or linkage, more often today it is controlled electronically by the engine management system, so you are, to use an aircraft term "Flying by wire"     As the throttle body handles a combination of filtered air, foul crankcase fumes and oil mist, it too has a tendency to become contaminated and clog up.  When this happens you can end up with an irratic idle, stalling, poor take off from start, poor starting etc etc.


  • The Fuel Injectors:  The final link in the engine management system!!  If the engine management has done its job properly, the injector "injects" what it is told to inject, delivering the fuel, more often than not these days, directly into the cylinder, to be ignited by either "spark" in the case of the Petrol engine or "compression temperatures" in the case of its diesel brother.   With modern petrol  and particularly diesel engines, it is vital to atomize the fuel as efficiently as possible.  The better the atomisation, the more complete the combustion and the cleaner the burn.    As I have already said, these little babies are operating in the most hostile environment possible so it is hardly surprising to find that they too get contaminated.  When injectors get fouled, engine efficiency suffers!!!   This can lead to POOR PERFORMANCE!   HESITATION!!   FLAT SPOTS!!!   POOR FUEL ECONOMY!!!!   DIRTY EXHAUST EMISSIONS!!!!!

So, to sum up!   You can see how many problems can be caused by contamination build-up in fuel systems and engines, and we have only scratched the surface here!!!

The same contamination also builds up on the backs of inlet and exhaust valves, causing them to stick too!!  and on top piston rings, causing them to stick with a resulting drop in compressions.


All engines, petrol or diesel types need to have their engines, fuel systems and engine management systems cleaned on a regular basis, to remove contamination.

Even the very best "premium" pump fuels will not remove all of this contamination and with cheaper "supermarket" fuels the situation is much worse!!

Use a recognized fuel treatment to keep your engine running in top form!!  Clean & Green!!

Please click on the link below for more information on recognised fuel treatments: -

Recognised Fuel Treatments

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