Cylinder Analysis

This test is comprised of the following: Compression (dynamic) Ignition system Due to the complexity of the fuel injection system on HFM-SFI engines, only the compression test is meaningful. Compression (dynamic) General Information The compression test is performed over the starter current draw. The decompression cycle is measured to indicate the mechanical condition of the engine. This data will provide indirect information about engine timing, frictional horsepower and compression via data tables and scope patterns. Prerequisite: Engine: OFF Attach current clamps to battery negative (B-) terminal (on model 129, ground connection between transmission and chassis [accessible from underneath only] on right hand side; on model 140/202, left hand side). Wait for additional instructions to appear. Start engine. Engine at idle until further instructions. Display: Print display or diagram

Compression (dynamic)

a) 4-cylinder engine, Engine 102/111

Cylinder	Engine speed / cylinder rpm	ISS (A)	Engine speed rpm	Temperature °C
Ref.			221	35
1	193	57
3	244	65
4	196	55
2	251	63
Minimum	193	55
Maximum	251	65
Difference	58	10

Compression (dynamic)

b) 6-cylinder engine, Engine 103, 104 The relation of the curve to the cylinders is determined by the entered firing sequence 1 - 5 - 3 - 6 - 2 - 4, starting with cylinder 1.

Cylinder	Engine speed / cylinder rpm	Iss (A)	Engine speed rpm	Temperature °C
Ref.			250	35
1	249	27
5	248	29
3	249	31
6	250	30
2	250	30
4	250	30
Minimum	248	27
Maximum	250	31
Difference	2	4

Compression (dynamic)


e) 8-cylinder engine, Engine 116, 117

Cylinder	Engine speed / cylinder rpm	Iss (A)	Engine speed rpm	Temperature °C
Ref.			190	35
1	190	60
5	191	59
4	189	60
8	189	61
6	189	59
3	191	62
7	191	59
2	189	60
Minimum	189	59
Maximum	191	62
Difference	2	3

Compression (dynamic)

On 8-cylinder engines, the average current value between the cylinder banks is compared and the difference shown. This allows identification of engine timing failures.

	left cylinder bank	Iss (A)	right cylinder bank	Iss (A)
	5	59	1	60
	8	61	4	60
	6	59	3	62
	7	59	2	60
Total		238		242
Minimum		59		60
Difference

Compression (dynamic)

On 12-cylinder engines, the average current value between the cylinder banks is compared and the difference shown. This allows identification of engine timing failures.

	left cylinder bank	Iss (A)	right cylinder bank	Iss (A)
	12	26	1	28
	8	23	5	29
	10	27	3	22
	6	26	7	27
	2	25	11	26
	4	26	9	26
Total		153		158
Minimum		25		26
Difference

Ignition System

a) 4-cylinder engine, Engine 102 During the Ignition system program the following data must appear on the engine analyzer:

Cylinder	Engine speed rpm	Engine oil temperature °C	Ignition voltage		Projection point, burn voltage
			kV max 1)	kV	kV	ms
Ref.	855	69
1			15	13.0	1.0	2.6
3			14	10.0	1.4	1.8
4			12	10.5	1.0	2.6
2		Defective cylinder	11	7.8	0.9	1.9
Minimum				7.8	0.9	1.8
Maximum				13.0	1.4	2.6
Difference				5.2	0.5	0.9

1) The "kV max values" are stored peak values. They are used to evaluate the spark plugs after brief acceleration. The kilovolt clamp must be positioned as close as possible to the ignition coil.

Ignition System

b) 6-cylinder engine, Engine 103 During the Ignition system program the following data must appear on the engine analyzer:

Cylinder	Engine speed rpm	Engine oil temperature °C	Ignition voltage		Projection point, burn voltage
			kV max 1)	kV	kV	ms
Ref.	855	69
1			15	13.0	1.0	2.6
5			14	10.0	1.4	1.8
3			12	10.5	1.0	2.6
6			13	11.3	1.0	2.7
2		Defective cylinder	10	7.3	0.8	1.5
4			12	12.2	1.2	1.7
Minimum				7.3	0.8	1.5
Maximum				13.0	1.4	2.6
Difference				5.7	0.6	0.9

1) The "kV max values" are stored peak values. They are used to evaluate the spark plugs after brief acceleration. The kilovolt clamp must be positioned as close as possible to the ignition coil.

Ignition System

c) 8-cylinder engine, Engine 116/117 During the Ignition system program the following data must appear on the engine analyzer:

Cylinder	Engine speed rpm	Engine oil temperature °C	Ignition voltage		Projection point, burn voltage
			kV max 1)	kV	kV	ms
Ref.	673	88
1			15	12.3	1.2	1.7
5			12	10.3	1.0	1.6
4			14	11.5	1.2	1.8
8			12	9.5	1.0	1.7
6			14	12.3	1.1	1.8
3		Defective cylinder	11	7.8	0.9	1.9
7			14	12.0	1.2	1.8
2			11	9.5	1.0	1.7
Minimum				7.3	0.9	1.6
Maximum				13.0	1.2	1.9
Difference				5.7	0.3	0.3

1) The "kV max values" are stored peak values. They are used to evaluate the spark plugs after brief acceleration. The kilovolt clamp must be positioned as close as possible to the ignition coil.