jwill213 Posted January 14, 2012 Report Share Posted January 14, 2012 Question about my '98 Lumina LTZ with a 3800. Several times in the last month, the car has absolutely bombed out on the interstate, typically in the same general pattern; after a few minutes of normal cruising at ~70 mph, it noticeably jumps/lurches/shudders (feels about like you're hitting a dip in the road), then begins to lose speed and rev through the roof simultaneously. The tach swings wildly between the "normal" ~2200 rpm@70 mph, up through the mid 3500s, briefly touches redline, and sometimes drops down as low as 1000 rpm; sometimes it will also jump in increments of a few hundred rpm randomly for a few minutes afterwards. The car seems unable to shift between gears whenever this happens (I can almost totally floor the accelerator with no response). I typically dive off at the nearest exit, turn the car off, wait for a few minutes, and can then go for hundreds of miles without issue. What could be happening? All fluid levels are perfectly fine, dash temp gauge is well below the midpoint, etc. A little background on the car: Purchased a year ago right at 100,000 miles, 136,000 miles currently on the clock, plugs and wires were replaced at 90k, fuel filter replaced at 90k. Dealer flushed the old coolant and changed the tranny fluid/filter at 120k. I assume there are underlying transmission issues, since even mildly hard acceleration from a dead stop results in awful shudder/wheel hop for several seconds before any movement happens. Quote Link to comment Share on other sites More sharing options...
jman093 Posted January 14, 2012 Report Share Posted January 14, 2012 Get the check engine light scanned and see what codes it has. Quote Link to comment Share on other sites More sharing options...
95 vert Posted January 14, 2012 Report Share Posted January 14, 2012 Trans is definitely going. Shutting it off and restarting makes the problem go away? I'd suspect it would have to be electrical. Quote Link to comment Share on other sites More sharing options...
jwill213 Posted January 14, 2012 Author Report Share Posted January 14, 2012 It actually doesn't throw a CEL or a code. I've had it scanned twice, once at O'reilly and once at a dealer. Quote Link to comment Share on other sites More sharing options...
Jssuper Posted January 15, 2012 Report Share Posted January 15, 2012 When they serviced the transmission last, did they use the correct fluid? Thats definitely odd behavior and I would restrict the miles on the car until the cause can be determined. I would consult a reputable transmission shop, also check your receipts to determine the fluid type used on the last service. Some of the new transmission fluid is not correct for Dexron III applications. If this car were mine I would do another pan drop, filter replacement and use DEX VI fluid to be sure. If problem persists I would consult a trans shop. The problem is finding a reputable one. The last one I talked to wanted to use synthetic DEX VI in a Jeep.... which is always a reminder why I do things like this myself. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted January 15, 2012 Report Share Posted January 15, 2012 (edited) It actually doesn't throw a CEL or a code. I've had it scanned twice, once at O'reilly and once at a dealer. There is an ENORMOUS difference between getting the codes read, and getting the computer scanned. Code reading is the first five percent of a proper scan. There's a reason that code-reading is a free service at some parts stores--there's no brainwork involved; and very little time commitment. "I" would take the car to a transmission specialty shop, and ask them for a diagnosis based on the info you've provided. I'd expect them to connect a scan tool and then test-drive the vehicle. It'd be really wonderful if it'd act up during the drive, but there's no guarantee that'll happen since it's so irregular. First Guess: Shift solenoid problems--one or more is overheating/sticking/taking orders from Martians. Second Guess: Computer or wiring problems leading to erratic solenoid behavior. For whatever it's worth, my '92 Lumina with 4L60E has a history of false-neutral behavior when run HARD for a long time. This has been several years ago, and the details are kind of fuzzy, but I would lose OD and go into "neutral" with lots of RPM and no propulsion. Seems to me it would also do it in 2nd gear--false neutral, lots of RPM, car coasts--but not in first or third. Maybe it was OK in first and second, but troublesome in third and fourth. I forget. Once the trans cooled off with normal driving, it didn't do it again. Trans shop couldn't find a problem, and I quit beating the hell out of the gas pedal. Edited January 15, 2012 by Schurkey Quote Link to comment Share on other sites More sharing options...
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