Howdy all!
Long time lurker, first time poster. Got a 2008 Grand Prix 3.8L N/A base from my brother who passed away a few years ago. Believe it or not, it was on a lift in a tranny shop when he died, it got stuck in a parking lot and was towed to said shop the day before. I had called him that afternoon when I found out, and was supposed to hear back that night with details, but got a call from the paramedics on his phone instead. **Hug those you love often, you never know when your "last time" to see them will be**
Anywho, that shop was not very confidence-inspiring and wanted $2500 to overhaul the transmission, and with everything else to deal with, I just found a used one for I think $600 with 37K miles and had them put that one in. Car had just under 100K at the time, and that was about 50K miles ago. Other than telling me to pull over due to the tranny overheating one time (like 265 degrees!), I really haven't had any trouble out of either. About 10K miles ago, I installed an aux cooler, and after dropping the pan, changing fluid/filter and back-flushing the lines, finally got the heat to stay under 190, even on the interstate in summer. I was a happy camper!
Jump to about two weeks ago, it started slightly raising rpms like 300 or so cruising on a flat highway at about 65 MPH, then back down, then would repeat after 30 seconds or so. When I got to a slower, more curvey and hilly stretch of road, it was more pronounced, so I put the selector in 3 to keep it more steady (and disengaged cruise). Checked the fluid as soon as I got home, was at the low end of the good range, so I added about a pint and called it a night. Next day, took it for a test run, no change. Hit the internet and saw WAY too many possible 'causes' for this, figured out the quickest and easiest thing to try would be to pull the PCM fuses for an hour or so to reset. Another test drive and it was worse! Now it 'bucked' a few times, too, mostly under slight throttle up a hill around 40-45 MPH. Backing off or pushing on the throttle would stop it. Harder throttle it wouldn't do it. OK, read some more about cleaning MAF and TB, also about some saying pulling negative battery cable like overnight, so I did the latter and planned on getting cleaner the next day. No change (except for a something weird I'll bring up later), even after the cleanings. Went on another (longer) trip to town to get/try some injector cleaner, and it wasn't really bucking anymore, but I had now seemed to loose either 4th or the TC completely! Read some more on average speeds for shift changes, went on another test drive to determine if it was 4th or TCC, and now I have a DTC - P0741! All of this has occurred within 150 miles or so.
Now for the weird part. Right after I started driving it years ago, I had that headlight issue where low beams would just go out, frantic flipping switches and flashing brights would bring it back, but there's not much scarier than driving down a curvy country road at night and having your lights go out! So, I replaced the headlamp relay/module (in the fuse box) and that fixed it. Except it did it again a couple of times on me about 1 week before this shifting weirdness started. Also, after pulling the two PCM fuses for an hour, the headlights went out completely, daytime running lights and all, and no flipping of switches would bring them back. Great! Well, after I pulled the negative cable overnight (see above), they are back on, operating normally! One more electrical weirdness happened a couple of hours ago. I had read earlier about pulling the main tranny harness under the TB to remove all signals, leaving R, 2nd and 3rd with full line pressure, and thought I'd try that a little to see if I could maybe free up the TCC or PCS with the added pressure, got in the car, closed the door, put the key in the ignition, and the doors locked!! I'm not kidding! I went ahead and turned the key to ON, waited for the fuel to pressurize (like I always do), turned the crank and all dash lights just went out. Turned the key to off pretty quickly, and watched all the guage needles do their little peg dance!!! With the dash as dark as night!!! Thought "well that didn't go well", unlocked the doors and proceeded to plug that connector back in. Got back in, started right up, just as normal as you please. OK, I'm going crazy, this didn't just happen, so I pulled the connector again, tried to start, and the exact same thing happened again, plug it back in, starts right up.....
for the
, but I'm hoping someone can tell me I'm not
!!!
Where do I go from here?!? Lucas Trans Oil? Transgo Shift Kit? dealer PCM reflash? Crazy house? My brother really loved this car, and so do I, so hopefully one of you gurus can help me out!
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