Vehicle Condition report for Norman McNeil

Inspection Number: 1129

Inspection Type: Vehicle Condition

Date: June 24, 2020

Vehicle Color: Black

VIN: WBA7E2C54JG741647

Year: 2018

Make: BMW

Model: 740i

Mileage: 34370

Engine Type: Gasoline

Engine Size: 3.0 Liter

Transmission: Automatic

Drive: Rear Wheel Drive

Customer Concern

On cold starts the engine runs rough for approximately 15-20 seconds.

Findings

Prior to starting the engine the cooling system reservoir was checked to see if exhaust gases were present in the cooling system. Two different tools were used to perform this test. One tool detects carbon dioxide and the other detects carbon monoxide. Both tools did detect traces of combustion gases before and after the engine was started. Combustion gases in the cooling system is indicative of an internal engine issue.

At start-up the engine had a rough idle for a little less than ten seconds. Once the rough idle went away the engine idled in a normal fashion for the rest of the inspection. When the engine was started (at the beginning of the inspection) it was the first start of the day.

Before the engine was started two different pressure transducers were placed at the left side exhaust outlet. In addition, a back probe was placed at one of the wires for the ignition coil for cylinder one so that a ” cylinder synch” (a reference) would be present. The two aforementioned transducers were then connected to an oscilloscope so that the exhaust pulses (positive and negative pulses) out of the exhaust) could be monitored when the engine was first started. If a reference cylinder is selected and the engine firing order is known the individual exhaust pulses can be identified and ultimately used to detect cylinder specific combustion anomalies.

When the engine was started the transducers detected misfires at cylinders three and five. The exhaust pulses for cylinder two had some irregularities as well. More specifically, the pulses for cylinder two (right after start-up) were lower and not as defined  as some of the others. Later in the waveform it was easy to see how the engine idle quality had improved.

Scan tool data (Mode Six) showed misfire activity at cylinders four and six before the engine was started and at cylinder six after the engine was near normal operating temperature. There were no stored, pending or active diagnostic trouble codes.

Addendum:

A second inspection was done on Tuesday, September 22nd at 3:15pm. At this time the cooling system was checked again for the presence of combustion gases. Three different tools were used to do the tests. Two of the tools are designed to detect carbon monoxide, while the other tool will alert to the presence of carbon dioxide. When placed over the coolant reservoir all three tools quickly detected the gases that they were designed to detect. The carbon monoxide levels were higher than the previous inspection.

The engine had a rough idle for less than 15 seconds. Afterwards the engine idle quality was normal as the engine transitioned from fast idle to natural idle.

Beginning Mileage: 34370

Ending Mileage: 34372

Inspection Time: June 24, 2020 10:15 am

Inspection Location: 2602 Tulip Poplar Circle Durham, NC 27704

Temperature at Time of Inspection: 79 degrees

Humidity at Time of Inspection: 61 %

Weather Conditions During Inspection: Mostly clear skies

Odometer
Tire placard
Left front interior
VIN
Engine compartment
EPA sticker
Engine compartment VIN
Right front 3/4 view
Front undercarriage
Left front 3/4 view
Right rear of the vehicle
Left rear of the vehicle
Checking for exhaust gases in the cooling system
Checking for exhaust gases in the cooling system
Checking for exhaust gases in the cooling system
Coolant reservoir
Checking for exhaust gases in the cooling system
Checking for exhaust gases in the cooling system
Test equipment at the exhaust outlet
Test equipment at the exhaust outlet
Data gathered via an oscilloscope
No diagnostic trouble codes
Fuel rail pressure before starting
Mode six misfire data gathered at the beginning of the inspection
Mode 6 misfire data gathered towards the end of the inspection
Monitors are complete
No permanent diagnostic trouble codes
Cylinder five misfire with piston position chart
Cylinder five misfire
Cylinder three misfire with piston position chart
Misfire at cylinder three.
Cylinder three misfire
Cylinder three misfire
Engine idling smoothly
Weak exhaust pulses at cylinders two and five
Exhaust pressure sensor
Exhaust pressure sensor
Carbon monoxide detected in the cooling system
Carbon monoxide detected in the cooling system
Carbon monoxide detected in the cooling system
Carbon monoxide detected in the cooling system
Carbon monoxide detected in the cooling system

Disclaimer

These are not safety inspections.  These reports constitute the inspector’s opinion on the condition of the vehicle at the time of inspection.  Some parts/components perform perfectly until the moment of failure. Failure may occur suddenly and without warning.

These inspection reports are intended to be used for informational purposes only and are not to be considered a recommendation against or for the purchase of the inspected vehicle. Therefore, any liability is strictly limited to the amount charged for these reports and AutoSpec is not responsible for any consequential damages or other damages beyond the fee paid for these reports.

In addition, changes in the vehicle inspected can occur and/or manifest themselves between the time a vehicle is inspected and when the vehicle is actually purchased, including, without limitation, physical and mechanical damage, wear and tear, owner modifications and/or substandard repairs. These changes may detrimentally impact the value and/or desirability of the vehicle.     

AutoSpec specifically disclaims any liability for any loss or damage arising in connection with ownership or operation of said vehicle AND further disclaims any liability of any hidden wreck, flood damage or tampered components not readily apparent.

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