The other day, I took an hour ride and coming home got stopped at a couple red lights. When I went to go, the trans felt like it never went back to first (lever in Drive), so it felt mushy accelerating. It started going for a second or two, then kind of stuttered and almost sounded like a small backfire/misfire, and finally the trans went down to first. Today it seemed fine and normal. I have not looked yet to see if there may be any codes. Anyone ever experience this before? Car is a 2008 4.6, no tune, no CAI, and had a full tune up a couple months ago to include plugs, coils and fuel filter. The fact it seemed normal today is kinda confusing.

 

Automagic's solenoids are probably not happy, as a first guess. Valve bodies second. 5R55X issues. That's what it sounds like to me, from waaaaay over here... That it's intermittent is part of my thought process on that. It can go right back to normal for a bit because electronics. Just like a throttle body did to me. Wrench light, restart, works ok for quite the while... then again... again, but shorter... new throttle body later fixed.

Hope that helps, even if it's not the right guess.

 

Only way to find out for certain, is connect a hand-held scanning device for error codes, otherwise, your just guessing.. Once you locate the error codes, you'll be able to narrow down/troubleshoot as to what is causing your acceleration/stuttering issues.

 

Hooked up a code reader, only thing there was a thing that said General Error 21000. So I guess I'll have to wait and see if it does it again, or bad enough to throw a readable code

 

If the code reader doesn't throw a readable code? then I would recommend having a reputable auto tuning/repair center connect your vehicle's OBDII port to one of their more advanced diagnostic scanners in order to locate readable codes

 

That code is not an ECU code. It's a code to indicate the scanner can't connect to the car's computer(s). Either the wiring is shot in some way, or the scanner's broken... or the computer(s) are fried/incorrectly configured/programmed. One hopes it's not 'fried'. Also, in case this matters, not all code readers read other modules, just the ECU (engine computer), so they won't help you diagnose anything (EDIT)not(EDIT) engine stuff. So if it's a transmission (or what do I know, maybe it's the ABS system) you won't get the info you need... but I don't know what code reader you connected.

Your best bet is what m05 says and take it somewhere that can do the work/diagnosis. That said, there is the free FORSCAN software and whatever dongle cable they recommend, plus a Windows(?) laptop with a USB connection, and you can use that to do just about anything you want to the car, including programming keys and modules (for a fee, they don't include that in free.) I've got that setup... and not yet done anything with it, but it's a thought. Think the cable's something like 30 bucks on that forest-y site. Supposedly it does it all, tests and everything. Maybe it's worth a look for you.

 

I also hope for the OP's sake that neither the wiring is shot in the scanner nor broken and especially hope the computer's ECU isn't fried nor programmed incorrectly. I suppose until the OP is able to have his car diagnosed by a reputable tuning/repair center, he might consider taking his car to either Auto Zone or Pep Boys who can connect one of their hand-held scanners to find out if any codes come up..
If their scanners are able to read his vehicle's ECU? then the OP will at least know for certain something is wrong with the scanning tool device he used that wasn't able to connect to his car's computer

 

I had recently purchased a used SCT X4 tuner and used that to try and read the trouble codes. I have another reader that I have used before, so I'll try that one. I don't think the wiring or ecu are an issue, I ran a few errands this morn with the car, ran fine. Ok, got a good link, no codes stored. Guess we shall see what happens.