Getting the best out of engine pressure analysis

James Dillon explains why you need to get your mind working at the same speed/cycle time as an engine does

FIGURE 1- old style vacuum/ pressure gauge

Published:  28 March, 2012

IT IS OFTEN

Figure 1

Figure 2

It is simple but you need to get into 'the groove' of how and what it is measuring and get your mind into working at the same speed/cycle time as the engine does.  Once you can understand this, you'll be amazed at the level of detail which is available. You may consider that you know all about the engine mechanicals. Can you answer the following two questions? How long does it take a four stroke engine (at idle speed - 800 rpm) to complete one revolution of the engine and how many degrees does this engine rotate, on average, in one millisecond? Everyone who has been on one of the Technical Topics Advanced Oscilloscope training courses will, at this moment, be shouting the answers into their copy of the magazine, other clever folk will do the maths; the rest of us may not know. Understanding the engine function at this level of detail is critical to getting the best out of engine pressure analysis.

Pinpointing difficult faults

Figure 6

The root cause of the case in point was that inter-cam timing was a tooth out. Being able to pinpoint this type of difficult to diagnose fault, with minimal removal and refitting of components, delivers large benefits leading to quick and accurate diagnostics. When you consider all of the other difficult to diagnose faults or components which this relatively quick method of testing can prove or disprove, it becomes hard to justify not having a pressure transducer in your diagnostic arsenal.

Let me give one final piece of advice - get some training in these diagnostic methods as interpretation is the key. Repeated feedback from people who've adopted our methods is that they wonder how they ever managed before.

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