Many years ago I wrote an article titled “Brutality.” The article was about Toyota’s severe 2-3 shift issues with their U140/U150 series transmission. At that time the most common reason for this dilemma was a defective PCM.
Our technical help line is now experiencing a different transmission that can have a variety of severe shifts complaints. It is with Ford’s 6R60/80 transmission. We received one such call from Mr. Transmission in Louisville, Ky., with a 2007 Explorer Sport 4.6L that had 65,000 miles. It shifted fine until you went for passing gear out of 4th. The shift was so brutal that it felt like the transmission went into reverse. There were no codes present. An entirely different call was a complaint of firm shifts and during full throttle kickdowns the vehicle speed signal would drop to zero. It too did not have codes. Yet another call received, all the shifts were extremely severe and it had a variety of CAN BUS codes stored.
In other words, there is a variety of harsh shift related conditions with no codes or codes stored that do not point to the cause of these problems.
Ford 3-valve modular engines such as the 4.6L, 5.4L and 6.8L use coil-on-plug primary ignition with long-reach spark plugs. The coil packs and/or spark plugs become faulty causing these brutal shift complaints (figures 1 and 2).
It is imperative that you put this in the forefront of your thinking when diagnosing various shift-related complaints. Especially so since in most cases it will not store any codes related to the cause. In fact, in all the cases we have dealt with to date, there were no misfire codes stored in the PCM. This does not mean to say that it will not store a misfire code in all cases.
To diagnose this, it is recommended to look at misfire counter data even if no misfire codes are present. Mode $06 may also be helpful. Performing a cylinder power balance test is a very good way to find the offending coil or plug.
Of course changing long-reach spark plugs on engines 2008 and earlier is another article in itself. After 2008 long-reach plugs are not used. But with the engines that do use them, care must be taken to pull these plugs as they have a tendency to break. It is recommended to bring the engine up to operating temperature and perform a top-engine decarbonizing. Pull the coil on plug off and spray the plug with some rust inhibitor. If a plug should break in the head, there are spark-plug extractor tool kits available like the Lisle LIS65600. Be sure to put anti-seize compound on the new plugs to end the job right.