engine hydrolocked
Senior User
Joined: May 2009
Posts: 105
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No not necessarily on the oil change if it has less than 4,000 to 5,000 miles since the last oil change. Gas getting into the oil should not cause any harm to the engine or the oil itself. I hope they adjusted the pulse width of the new injectors so they will spray sequentially as their suppose to, otherwise varnish can build up in them and cause them to malfunction again. The mechanics use a scan tool to adjust the pulse width of the injectors by interfacing the adjustments through the PCM (Powertrain Control Module). Hope this answers your question.
Jim
Jim
Wouldn't that be done automatically? Is the PCM programmed that way from the start? I thought that would be something you didn't have to worry about being wrong????
Elder User
Joined: Jan 2008
Posts: 605
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On Top Fuel the oil is changed when the car gets back to the pits after a pass. Once the car is serviced the engine is started so the crew can check for leaks and set the timing(ever try grabbing a 44AMP MSD Magneto to adjust timing-scary stuff). The engine is shut off and the oil is changed AGAIN(2nd time in 1/4th mile). The amount of liquid(gasoline) needed to hydraulic an engine is dependant upon how much volume there is when the piston is at TDC. If the injectors are stuck open or leaking this could happen. As far as adjusting the PW of injectors is concerned it can't be done. Injectors aren't that smart. The are either commanded open or closed. They can malfunction and leak or fail to open(defective coil or pintle), but they can't be adjusted in any way to stay open or closed (different PW). That function is done on the fly by the PCM based upon the fuel tables, TPS, MAP, MAF, IAT, ECT and feedback from the O2 sensors. The sensor values are fed to the PCM which goes to the fuel tables to ask for the correct PW in millisec. You also have to take the LTFTs into consideration. You can go to bigger injectors for more fuel if needed when the duty cycle goes over 80%, but a stock engine isn't going to require that much fuel.
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rkurkowski
1999 - 2003 7.3L Power Stroke Diesel
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May 13, 2011 11:01 PM
