Odd selectshift / transmission issue

rudy3285

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I've got a weird issue with the selectshift in my '02 LSE V8. I posted in an old thread with a similar issue (the only mention I could find of this issue on the internet), but there were no responses (http://www.lincolnvscadillac.com/forum/showthread.php?94091-Trans-Shift-Problems), so I'm starting my own thread.

When I put the car in selectshift mode, pressing the throttle more than 60% should cause the transmission to downshift to 1st gear, which the car starts to do, as the number on the dash goes from 2 to 1, but then the car makes a jolting stop, the RPMs drop and the tires bark. The car starts driving backwards (in reverse), but it is a harsh engagement--very jerky. I didn't feel comfortable keeping my foot in the throttle to see what would happen long-term, but it felt like the car was fighting between finding reverse and a forward gear. If I slide the shifter back to D5, the problem goes away. Additionally, in D5, the car will downshift from 2 to 1 and accelerate normally, with no reverse engagement.

A perhaps related symptom: Sometimes when the car is first started up and driven, when driving out of my apartment's parking lot in D5, the car will have the same sudden stop and dropping of the RPMs, but the tires do not bark. I just let off of the throttle, and the car 'finds' a forward gear and I continue on my way. It doesn't happen every day, but when it does, it is generally only when the car is cold and being driven for the first time during the day. I am not sure if it is the same problem as with the selectshift (as listed above) since it isn't downshifting from 1st (not giving it more than 60% throttle, just easing it out of the parking lot to get to the street). I'm not really sure what's going on in this case, if it is trying to find reverse, or if it is an entirely unrelated problem.

Any ideas? I suppose I could take it to the ford dealership and demonstrate the selectshift problem to see what they think...

I like the car a lot, have 109K on the clock. I've had most of the regular issues: replaced all the coils, valve cover gaskets, done a few window regulators, had the driver's interior door handle break, had DCCV issues, now I suppose it's my turn to get the weird transmission issues, too.
 
I've done some more reading, could this be my PCM failing? From another thread, it was stated that failing coils could cause RF interference, damaging the PCM. Well, I've had a coil fail completely, causing the car to run on 7 cylinders for a very short time (all 8 coils were replaced at about 80K). The PCM failing seems to make the most sense to me since the transmission behaves normally when in D5, but not in selectshift mode. It was stated that PCMs can be tested by sending them to http://www.siaelec.com/ which is probably the route I would take.

Anybody think I'm on the right track? Thanks.
 
Could be. It's a helluva lot easier to pull the PCM to send off for repairs than to get into the transmission on these cars. The trans tunnel is TIGHT, and the trans was really designed for Ford's SUVs with a huge trans tunnels so some of the stuff is not quite as accessible as it could be. I had to cut a hole in the firewall in order to get at the bolt on top of the solenoid pack wiring harness because I couldn't fit my hand in and couldn't find a tool locally that would work (wasn't going to buy the specialized tool for a one time job). Since you had a coil failure, and the damage is progressive, you'd probably benefit from having it looked over anyway. If they don't find a problem I think it was a 50 dollar charge, with the max charge being 160ish bucks.

Incidentally, when you did the coils I hope you did the plugs as well. They are a team, and they fail as a team so if you didn't replace both it's likely you've damaged the new coils. When I did my PCM I went ahead and did new COPs and plugs at the same time just to make sure there wasn't going to be an issue.
 
Incidentally, when you did the coils I hope you did the plugs as well. They are a team, and they fail as a team so if you didn't replace both it's likely you've damaged the new coils. When I did my PCM I went ahead and did new COPs and plugs at the same time just to make sure there wasn't going to be an issue.
I installed new plugs when I did all the coils, yes. I have put 30k miles on since then without any trouble (beyond the weird transmission behavior, but that started before I replaced the coils/plugs).

I will start with sending the PCM off for diagnostic testing when I have some time to tear the LS apart. Thankfully I have another car and can have the LS in pieces as long as need be. Thanks for your input.
 

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