Engine Bogs Down at Highway Speeds

[ChristineX5]

Thank you for your replies fellows! They are greatly appreciated. Both replies focus on the automatic. That worries me as I know little about these complex units. All I have ever done is change fluid. The fluid change with no pan/filter combo took 7 liters of the good ZF fluid. Correctly filled while running at proper temp. No leaks, not a drop ever on garage floor.

I did not have time for a highway run today. But I did have time for a nearby "Sunday Drive." A half dozen times I took her from zero to 60, paying careful attention to all the sounds and shift points, etc. All seemed normal. Engine sounded very good, shifts crisp and normal.

If this has any value... it did catch my attention. On one acceleration with medium throttle, it had progressed nicely through all the gears, very normal and relaxed in full automatic, but when it went into 6th top gear, maybe ten seconds later it downshifted back to 5th, without any noticeable need to do so??? I remember asking myself... "why did it do that?" There was no need for further torque as my gas pedal was steady?

For those with fuel injector knowledge...

Could I have an injector/injectors that have some crud built up in them? But not enough to throw a code? Remember...we are just light on power on the highway with the 2,000 pound trailer. The wife said it feels fine now up on the highway without the trailer. I have not had a chance to drive it on the highway.


I have also added today a full bottle of Sea Foam in a full tank of gas. (Sea Foam did wonders on my 225 Johnson outboard that is 22 years old. Has not run this good in over ten years, with strong power like new! Just amazing IMHO, not at all "snake oil." All the gas cans for my small equipment (chain saw/pressure washer/lawnmower, etc., now get 4 ounces per 5 gallons. Keeps the gas good too. And everything starts up like new, time and again, and I leave the gas in over winter, year round. But be careful... --less is more.-- It's plenty strong, and work into your equipment gradually to clean everything.

Has anyone here pulled and cleaned the fuel injectors? And the results please? Thank you again. I will keep you all posted so we can all learn what this was.



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