Scan Tool Diagnosis #1

1. Use the following scan tool data for this question. The engine is idling in the shop. It has a regular engine miss and has failed a smog inspection at idle with high CO. What is the likely problem with this Theory Car engine?

Frame		-8	-7	-6	-5	-4	-3	-2	-1	0
TPS: (v)		1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0
MAP: (v)		1.3	1.3	1.3	1.3	1.3	1.3	1.3	1.3	1.3
ECT: (v)		0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
O2: (v)		0.3	0.0	0.2	0.1	0.0	0.0	0.1	0.3	0.0
RPM:		800	800	810	800	810	800	810	800	800
INJ: (ms)		2.9	2.9	2.9	2.9	3.0	3.0	3.0	3.1	3.1
LFTRIM: (%)		+15	+15	+15	+15	+16	+16	+16	+17	+17

MAP sensor vacuum line fell off.
Fuel pressure too high.
ECT voltage too high.
Fouled #2 spark plug.

 

2. The engine runs very rich and gets very poor fuel economy. Using the scan tool information below, what is the likely problem?

Frame		-8	-7	-6	-5	-4	-3	-2	-1	0
TPS: (v)		1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0
MAP: (v)		1.1	1.1	1.1	1.1	1.1	1.1	1.1	1.1	1.1
ECT: (v)		4.7	4.6	4.7	4.7	4.8	4.7	4.7	4.7	4.8
O2: (v)		0.9	0.9	0.9	1.0	1.0	0.9	0.9	0.9	0.9
RPM:		800	800	810	800	810	800	810	800	800
INJ: (ms)		2.9	2.8	2.9	2.9	3.0	2.9	3.0	2.9	2.9
LFTRIM: (%)		-4	-4	-4	-4	-4	-4	-4	-4	-4

Poor electrical connection at ECT sensor.
Bad thermostat.
Low battery voltage.
Plugged catalytic converter.

 

3. A technician is driving a car with the scan tool connected and he records a glitch when the engine hesitated as he was cruising. What is the cause of the intermittent problem?

Frame		-8	-7	-6	-5	-4	-3	-2	-1	0
TPS: (v)		2.2	2.2	2.2	0.3	2.2	2.2	2.2	2.2	2.2
MAP: (v)		1.9	1.9	1.9	2.1	1.9	1.9	1.9	1.9	1.9
ECT: (v)		0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
O2: (v)		0.7	0.3	0.8	0.0	0.0	0.7	0.8	0.2	0.4
RPM:		2600	2600	2600	2450	2550	2600	2600	2600	2600
INJ: (ms)		4.8	4.8	4.8	1.2	4.8	4.8	4.8	4.8	4.8
LFTRIM: (%)		+3	+2	+3	+0	+3	+3	+3	+3	+3

Intermittent O2 sensor connection.
MAP sensor intermittent.
TPS sensor intermittent.
Plugged catalytic converter intermittently.

 

4. A car owner complains of a lack of power when cruising. The emissions at idle look clean. During a road test with the scan tool our technician recorded the following data. Please look at it before answering the question: What's wrong?

Frame		-8	-7	-6	-5	-4	-3	-2	-1	0
TPS: (v)		3.1	3.1	3.1	3.1	3.1	3.1	3.1	3.1	3.1
MAP: (v)		3.4	3.4	3.4	3.4	3.5	3.5	3.5	3.5	3.5
ECT: (v)		0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
O2: (v)		0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
RPM:		1900	1900	1900	1900	1900	1900	1900	1900	1900
INJ: (ms)		6.4	6.4	6.4	6.4	6.5	6.5	6.5	6.5	6.5
LFTRIM: (%)		+20	+20	+20	+20	+20	+20	+20	+20	+20

Bad O2 sensor.
Plugged fuel filter.
Plugged air filter.
Bad MAP sensor.

 

 

5. A car has just failed a smog inspection and the customer also mentioned that the fuel economy had been really bad lately. Our technician recorded this scan tool data at idle while he noticed lots of black smoke coming out the tailpipe. What do you think is wrong?

Frame		-8	-7	-6	-5	-4	-3	-2	-1	0
TPS: (v)		1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0
MAP: (v)		1.1	1.1	1.1	1.1	1.1	1.1	1.1	1.1	1.1
ECT: (v)		0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
O2: (v)		0.9	0.9	0.9	1.0	1.0	0.9	0.9	0.9	0.9
RPM:		800	800	810	800	810	800	810	800	800
INJ: (ms)		1.9	1.9	1.9	1.9	1.9	1.9	1.9	1.9	1.9
LFTRIM: (%)		-18	-18	-18	-18	-18	-18	-18	-18	-18

Fuel pressure regulator stuck closed.
Bad spark plug wire.
Engine coolant temperature sensor out of range.
Intake manifold vacuum leak.

 

6. The engine stalls intermittently. After several days, the technician captured a recording on the scan tool that showed scan tool data when the engine started to stall, but then caught itself and kept running. Here is what he found. What do you think is wrong?

Frame		-8	-7	-6	-5	-4	-3	-2	-1	0
TPS: (v)		1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0
MAP: (v)		1.1	1.1	1.1	1.5	1.1	1.1	1.1	1.1	1.1
ECT: (v)		0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
O2: (v)		0.8	0.3	0.7	0.0	0.0	0.4	0.9	0.1	0.7
RPM:		800	800	810	0	610	800	810	800	800
INJ: (ms)		2.3	2.3	2.3	0	3.0	2.3	2.3	2.3	2.3
LFTRIM: (%)		+2	+1	+1	0	+2	+2	+2	+2	+2

Engine fuel injection stopped momentarily.
MAP sensor bad intermittently.
RPM magnetic pickup sensor bad intermittently.
TPS momentary glitch.

 

7. An engine appears to have several problems. When cruising, it wants to buck and jerk, has lots of hesitation when accelerating, and has a very uneven idle speed. It also surges at idle. But the engine doesn't miss regularly. The following data recording was taken at idle in the shop. Another clue: the exhaust emissions at idle have lots of HC and O2, even though this car doesn't have any air injection. What's wrong?

Frame		-8	-7	-6	-5	-4	-3	-2	-1	0
TPS: (v)		1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0
MAP: (v)		0.4	0.3	0.3	0.4	0.4	0.4	0.2	0.4	0.3
ECT: (v)		0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
O2: (v)		0.1	0.1	0.0	0.0	0.0	0.2	0.1	0.1	0.0
RPM:		820	800	810	800	790	810	800	800	820
INJ: (ms)		1.8	1.7	1.7	1.8	1.8	1.8	1.6	1.7	1.8
LFTRIM: (%)		+5	+5	+5	+5	+5	+6	+6	+6	+6

Spark plug wire #3 has an open circuit.
EGR valve stuck partly open.
O2 sensor doesn't work.
MAP sensor out of range.