This month's tech tip focuses on using the PDA 5 Gas Emission Analyzer and the PDA PC-Link to diagnose an emission failure or a driveability vehicle. No codes present but has a history code of Lean Exhaust.
HC = 400PPM
CO2 = 10.5%
CO = 1.5%
O2 = 3.5%
This vehicle is not equipped with an AIR Pump. EGR is functioning properly. PCM is able to go into closed loop operation. This is a normal scenario often in today's repair shop business.
Let us now review the results of the tailpipe readings and start with the basic testing. Assuming that Fuel Pressure and Volume has been confirmed to be at specs, we now perform a Power Check test using the Engine Test feature of PDA PC-Link. The results of the Power Check test are shown in Figure. 1.
If you have 2 COM ports on your PC you can run the PDA 5 Gas at the same time as the PDA PC-Link. One of the advantages of doing this is to perform both tests at the same time. While performing the Power Check test with PDA PC-Link, the PDA 5 Gas software can record the gas readings during the test. The recorded gas file is shown below in Figure 2. Any cylinder that shows an abnormal reading compared to others will give us an indication if the vehicle is having a fuel delivery problem or if it is an ignition problem. Note the use of the cursor to measure the HC peaks during the Power Check test.
User Tip |
While shorting cylinders during the engine test observe the HC readings, if they are low for any given cylinder suspect that cylinder's injector to be dirty or defective. If the HC's are low all across the range check for restricted fuel filter or a defective fuel pump. Also, be sure to check fuel volume. Use the MilliAmp probe to check the waveform of the fuel pump, which will indicate the performance of the pump. Use the Browse Waveform Feature to identify a good and a bad fuel pump waveform. |
