Balance Motor Works believe in working with our customers in a fair and reasonable manner. We are not, what is known in the trade as “parts changers”. That means just because we think there’s a possibility that a failure of a part may be causing the symptoms, we won’t change it, without firstly diagnosing a fault in its operation. This requires skilled diagnosis,, and understanding, of the way the parts function. For example, if we suspect the operation of a throttle potentiometer is causing a problem, we will check the operation and voltages through the on-board diagnostics, and if necessary on the sensor itself.
This methodology reduces the possibility of unnecessary expense, changing electrical (and to a lesser degree mechanical) items, only to find the same fault remains. Naturally the balance must be struck between the Labour costs of diagnosing faults if the replacement part is particularly cheap to purchase. So , if we remove a set of spark plugs when a car has developed a misfire, and we can see that the gap in the plugs is large and they are clearly at the end of their service life, we will not hesitate to replace these items, rather than clean and re-gap them and then retest. It might be different story if the car is of a certain vintage and the plugs are not available!
In many cases you will find a great deal of information online, where people have a similar fault, and it’s proven particularly difficult to fix. It appears even main dealers have struggled and have started changing parts without really knowing where the fault is lying, in the somewhat blind hope that it will fix it.
On a recent car we worked on, it developed a fault where it would not rev past 4000 rpm. initial investigative work struggled to find the reason because the diagnostic system was not pointing to there being any faults at all with anything. Something caught my eye though – the Knock sensor was pulling 20 degrees of spark out without load, when you revved the engine without load.
This pointed to a faulty knock sensor, excess retard would explain the unburnt fuel in the exhaust. The knock sensor was replaced and then only approx 5 degrees of spark advance was being pulled. However what the faulty knock sensor had done was damage the cat. We found this out when some bright spark suggested we run without the diagnostic Lambda sensor. Straight away the engine revved up fine. The cat had overheated with the retarded spark and unburnt fuel, leading the matrix to melt and block so badly the car was choking on it’s own exhaust fumes. Pretty quickly you enter a viscious cycle, and something has to give.
So in this instance the car was fixed with a new catalyst and a new knock sensor.
Why are we telling you this? Hopefully to convince you to bring your car with faults, to us to fix. We actually find it very satisfying to just fix the bits that are faulty, and give the customer back a car that runs well.
It’s better value all around and we are doing our bit to ensure that components that work fine, are not needlessly replaced.
