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> Cool Tools > Engine Relationship Charts


Engine Relationship Charts

California Residents: Proposition 65 Warning
Case Study

When performing compression or cylinder leakage tests, knowing which event each cylinder is on and the position of the valves will help you interpret the test results.

The Engine Relationship Charts color code and label each cylinder event in relation to all the other cylinders so you can visualize the relationships between pistons and valves.

The charts are durable and laminated, can be marked up and cleaned, and used over and over.

Use the charts in the shop and in the classroom for a variety of diagnostic and teaching tasks.

DIAGNOSTICS. Use while performing: cylinder leakage test analysis, pressure and vacuum waveform orientation, single cylinder fuel delivery identification, exhaust pulse analysis, dip stick tube pressure analysis and more.

EDUCATIONAL. Use to discuss: the four stroke cycle, illustrate piston relationships to one another, visually explain valvetrain functions, show valve overlap, explain causes of lost compression, analyze cylinder leakage test results and more. Classroom packages available, please contact AESwave.

Each chart is color printed onto a regular sized sheet (8.5” x 11”) with thick 5mm lamination. Write directly onto the lamination of page with a dry erase marker or a grease pencil. The charts are held together by a locking steel binder ring.

The package consists of 6 laminated charts and includes one chart for each of the following engines: 3-cylinder, 4-cylinder, 5-cylinder, 6-cylinder, 8-cylinder and 10-cylinder.

Please note:
- All sales are final for this product. 
- We accept returns for an exchange in the event that the item is damaged while in transit. 
- To be eligible for a replacement, you must email us pictures of the damaged product within 7 days of receiving the product.

Case Study


The subject vehicle is a 2007 Ford Focus with a misfire on cylinder number four.


A relative compression test was performed and low compression on cylinder four was suggested. The spark plugs were then removed and cylinder four was the only one whose compression tested very low. A cylinder leakage test was then performed with all of the spark plugs removed and cylinder four at top dead center of its compression stroke. Air could be heard, and felt, coming out of the number three spark plug hole.


Air coming out of an adjacent cylinder could indicate a bad head gasket. However, this vehicle was full of coolant, not overheating, no white smoke was coming from the tail pipe, cylinder three was not misfiring and cylinder three’s compression tested good. The likelihood of a bad head gasket in this case is slim to none. So where is the air coming from?


With a dry erase marker, the 4-cylinder Engine Relationship Chart is marked up to show the firing order of the engine, 1-3-4-2, down the left column and across the bottom of the chart.


Top dead center compression of cylinder number four is identified, and circled, on the chart.


According to the chart, cylinder four’s valves should be closed. Also, since cylinder three is where the air is escaping, that cylinder is examined as well.


The chart shows that cylinder three’s exhaust valve is open at the same position in the crankshaft’s 720 degree cycle. Therefore, the air in cylinder four must be escaping past its exhaust valve into the exhaust manifold and coming back into cylinder three through its open exhaust valve. The conclusion is that cylinder number four’s exhaust valve is either stuck open, not sealing or burned.


The cylinder head was removed and the fault was confirmed. The exhaust valve on cylinder four was burnt and allowing compression escape into the exhaust manifold. The cylinder head was repaired, and the vehicle was returned to the customer running good again.


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