Vehicle: 2005 F150 5.4L, 2wd, 155k; Plugs and phasers at 105k, regularly serviced

Issue: From a stop or slow rolling stop when throttle applied I get marginal/minimal acceleration. However, I see the rpm rev like there is no load, then will get a loud thud/slam and she will then take off. I also get an occasional thud when coming to a stop; also get odd RPMs when coasting and off throttle. Most likely unrelated, but I have the common shutter in rear end during slow turns, so I know i need to flush and replace diff fluid and add friction modifier.

Question/Concerns: Do I have a transmission/torque convertor issue? Or is this a simple grease of the slip yoke? Off chance, but could it be engine or transmission mount issue?


Thanks for all the help guys.

Ryan

 

Yes, your transmission is taking a dump. A mount or slip yoke can't allow slip/rpm issues. They can cause a "thud" under certain conditions but not the lack of acceleration with throttle application.

 

Have you checked your tranny fluid level?

 

^^^, and, if you have never changed it, you might consider running a can of BG44 in it for 50 miles or so the change filter/fluid in it and TQ converter.

 

dont ever run bg44 in trans u crazy? 44k is a fuel additive

 

Thanks for catching my lapse in correctness. You are correct. BG Products actually has a cleaner labeled specifically for transmissions.
https://www.bgprod.com/catalog/trans.../#bg-product-2


BG44 has acquired market status equal to that of soft drinks as a "Coke". Most likely the counter sales person has saved my hide and sold me the right stuff, but I've ran a //BG something// cleaner through my transmission for a few miles each of the 4 fluid changes in its 220,000 mile life. Each time, I believe I can feel a difference in the way it engages and shifts - even if it was 44k. They may all be formulated the same and touted as a cure all for everything like most additives are. But I do like BG products.

 

i also love bg products i work at a dealership and we only use bg

 

yeah tranny is on the way out. Checked fluids last night, color, smell and level were good. Today I got the transmission malfunction light went on and O/D off light started flashing. RPM and shifting went haywire.


Anyone know a good transmission shop in Northern Virginia?

 

My '02 F150 with 105K has developed an occasional problem ... when shifted into Drive, there will be a brief delay before it engages. I'm aware that Motorcraft offers some additives for transmissions and differentials. Some are labeled as Friction Modifiers. Any suggestions about which I should try or if I should do something else? Thanks

 

Have a transmission shop check it out, have many miles on trans service?