Remember where you started

Jan. 1, 2020
Let’s start off this month with a few general tips before diving into a case study involving a 2007 Ford F150 VCT (Variable Cam Timing) problem.

In between attending events around the country and my continued work educating techs in the U.S. and Canada, the first months of 2013 has been a whirlwind of travel with little time to breathe in between. And of all the duties I carry, writing this column for all the Motor Age readers is one of my most enjoyable.

Let’s start off this month with a few general tips before diving into a case study involving a 2007 Ford F150 VCT (Variable Cam Timing) problem I hope you’ll find both entertaining and informative.

Anyone who has ever tackled this job knows it isn’t the easiest to perform. Read over the OE service procedure anytime  you’re taking on something new to you.

Adding AIR Creates A Rich Mix?
The purpose of the Air Injection Reaction (AIR) system is to reduce hydrocarbon (HC) and carbon monoxide (CO) emissions left after the combustion process. AIR system failures often involve pumps damaged by moisture, vacuum hoses damaged by heat or check valves sticking open or closed from carbon buildup. Faulty AIR systems tend to make engines run rich. This will occur if the air from the pump enters the exhaust manifold before the upstream O2 sensor or does not switch to underhood when the engine is warm.

Atmospheric air is injected under pressure into the exhaust manifold upstream by the air pump. Air pumped directly into the exhaust helps to further oxidize exhaust gases before they enter the catalyst.

Some older vehicles switch air injection between the exhaust and the catalyst itself. Air is sent upstream right after the engine is started cold, but switches downstream when the catalyst warms up and starts to work. It is important to remember to disable air injection when you evaluate exhaust gas O2 levels, since air injection can elevate O2 levels and lead you to false conclusions.

Disabling air injection does not mean clamping off any air injection hoses and tubes. This might lead to permanent damage of hoses and valves. Instead, before taking tailpipe exhaust samples, follow the recommended OEM service procedure to disable the air pump electrically or to divert air injection to the vent port.

Keeping Your Balance
When you need to confirm and zone in on a fuel injector problem, the best test to perform without a bunch of expensive tools is a fuel injector balance test. Follow these steps to perform this simple test on most engines without breaking your tool budget.

All of this expense caused by the use of the wrong oil.

With the ignition off, remove the injector plug/wire connectors of the injector to be tested. Next, install an accurate fuel pressure gauge and fuel injector tester. The fuel injector tester is a special tool that allows you to operate the injector independently of the Engine Control Module (ECM). If you have a scan tool capable of performing this task, this step is not necessary.

Turn the ignition on off as needed to get the maximum reading on your fuel pressure gauge. Write that number down. If you are using a manual tester, select the “1 Pulse/500ms” option and press the “Activate Injector” button once. Record the reading on the fuel pressure gauge. The difference between what you started with and what you ended up with is the amount of pressure drop. Do this twice for each injector.  Be sure to start the engine up between tests on each cylinder to prevent hydrostatic lock, and to start each new test with the same peak pressure reading.

Once you’ve completed your testing on all injectors and have figured out the pressure drop for each, it’s time to compare. Determine the average pressure drop by adding them all up and then dividing by the number of cylinders tested. Suspect a problem with any injector whose drop exceeds the average by +/- 1.5 psi. An injector with a lower drop is probably restricted and passing less fuel while one with a larger drop is probably worn or sticking and passing too much fuel.

The F150 had misfire codes stored for cylinders No. 1 and No. 6.

Confirm your diagnosis and repair by using fuel trim. Fuel trim is information that is sent to the ECM and stored in memory as Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT) values. 

2007 Ford F150 5.4L VCT (Variable Cam Timing) Problem
This Ford came in with the MIL illuminated and a poor performance problem. A common problem on these engines is due to a problem with the VCT (Variable Cam Timing) system. So the first thing we checked was the oil, noticing it was new and filled. Our next step was connecting our EScan, checking for DTCs (Diagnostic Trouble Codes). We found the following DTCs stored in the computer; P0300 (random misfire detected), P0301 (cylinder No. 1 misfire detected) and P0306 (cylinder No. 6 misfire detected). These misfires DTCs can be caused by ignition, fuel or mechanical problems. We ruled out both ignition and fuel, leaving us with most likely a mechanical problem. To confirm the mechanical problem, we performed a relative compression test using the OTC Genisys EVOÒ scan tool. The results of the test confirmed that we had a mechanical problem that was causing the misfires.

Because this was the first time that we had seen this vehicle and customer, we had to ask what maintenance had been performed. The owner informed us that he was having the vehicle serviced at a local tire shop that offered a $19.95 oil and filter change. The oil that the tire shop used was 10W30 along with a cheap import oil filter. Because the proper oil and filter are critical to proper operation of the VCT system, we suspected that the system was damaged along with other problems. Ford requires 5W20 synthetic blend oil along with a Motorcraft (or service equivalent) oil filter every 5000 miles or 3000 miles if the vehicle is used in severe conditions, load and driving. The owner of this vehicle was in the construction business using the vehicle to haul a bunch of heavy supplies and a trailer. Remember that when using other than the recommended oil and filter, engine damage can occur prematurely. The correct oil is critical in this and every other variable timing system.

This OTC tool is used to manually fire the injectors in order to perform an injector balance test. Some makes support scan tool bi-directional control to do the same thing.

When we took the valve cover off we noticed that the phaser and solenoid was gummed up with burned oil. It’s always a good idea to know how a system works before tearing anything apart. A quick overview of the system is that the VCT is connected to the camshaft, controlled by the PCM via the oil control solenoid. The solenoid, by allowing or restricting oil flow (applying or releasing the cam phaser) controls the VCT system. The VCT phaser has four modes: idle, part throttle, wide open throttle and default mode. Adjustments are based on airflow, engine and coolant temperature, part and wide-open throttle, RPM, load, and throttle position. The purpose of the VCT system is to help reduce emissions, increase engine output, improve idle quality and of course increase fuel mileage.

Because of the improper maintenance, the fix for this 5.4L was pretty involved. With the customer’s approval, we had to replace the phasers, timing chains, and solenoids. We also had to clean the oil passages, remove the oil pan to access and clean the oil screen and pump. At least now this engine was once again able to pull the load and run smoothly.

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