Scan Tool and BG Services

Determining the vehicle needs.

The first step is to determine the vehicle needs by using the appropriate scan tool to access OBD readings. Carefully document all readings that can be accessed.

Once all data is documented you’ll review the readings to determine the readings that are out of a normal range for that vehicle. 

Use the readings to determine the type of service needed. The results will determine if an injection service(2910K), induction service(2902) or a combination of the two(2901/2914K) are needed to get the vehicle back into the normal range.

Verify the improvement by checking and documenting scan tool readings again when finished with the service and road test. Go over with the service advisors explaining why the results changed the way they did so it can be accurately relayed back to the customer/client. More info on deposits and DTCs.

Fuel Injection Service (2910K/2901/2914K)

Needle Valve- Deposits can build up in the needle valve leading to a poor and inconsistent spray pattern. The deposits can also restrict flow. A poor spray pattern can result in incomplete combustion and a rich condition from poor fuel atomization or even a lean condition depending on rate of fuel burn.

Injector Pulse Width- Is the number of mili-seconds the injector is open and spraying fuel. Standard varies but a good rule of thumb would be a 2.0-4.0 ms range.

Ignition Timing- Is the timing of the spark in relation to the crankshaft position. This is a value controlled by the ECM/ECU and the Knock sensor. The higher this value the better the vehicle is running. As deposits build up on the tops of the pistons the compression ratio goes up. With the higher compression ration the vehicle can run into pre-ignition issues. The knock sensor detects the pre-ignition and will retard the timing until there is no longer a knock concern. This happens very gradually and the vehicle never noticeable loses power. You’ll see values in the 10-2 degrees before tdc range and post road test you should see the value in the 13-14 range. This is service is best taken care of with the injection service.

Induction/Air Intake Service (2901/2902/2914K)

Throttle Position- The throttle position is the measured opening percentage of the throttle plate. As intake manifold deposits build up the throttle plate will need to open more to overcome the restriction of the built up deposits. This is a value that you can see as high as 7-8% without throwing a check engine light. After an induction service you should see it at 0.8-1.8%. This is something that can be monitored actively during service and usually remedied with the first can of 206.

Temperature Sensor- When looking at the temp sensor with the scan tool you’ll need to verify that the sensor is located in the intake manifold and not in the mass air flow sensor or the air intake tube. If it is located in  the intake manifold it is susceptible to the same intake deposits that the throttle actuator is effected by. The sensor operates by reading the change in resistance across a thin wire at different temperatures. As the deposits build on the wire it becomes insulated to the changes in temperature. This leads to a incorrect fuel mixture which will hurt efficiency and economy.

Calculated engine load- Determined by a combination of different sensors. Mostly Mass air flow readings in regards to current air volume compared to maximum air flow. Throttle position, Intake manifold pressure, Air intake temps sensor and coolant temp all factor in to the reading. This reading you can see as high as 30% in some vehicles but is usually lowered substantially utilizing a BG service. Also once the injection and induction services have been completed you can do a mass air flow sensor cleaning and  possibly lower it the percentage more. This can be greatly effected by a vacuum leak so make sure the reading is taken before and after an induction service with the S-tool. The small vacuum leak between the boot and S-tool will effect this number.