engine misses above 3000rpm when downshifting

118K miles 2003 Taurus 3.0 12V engine

At 100K had dealer replace plugs, wires, fuel filter, transfluid, coolant. Car drives fine. From standstill normal acceleration car runs great to 3000rpm and shifts to 2nd, then great to 3000rpm shifts to third, usually stop between 2000rpm and 2200rpm which is about 60 to 65 mph and car will cruise fine at that speed. If I attempt to pass and push accelerator to floor, car is smooth to 3000rpm, as tach needle goes over 3000, car starts to jerk and jump, needle bounces from 3100 to 3500, trans seems to go back and forth between O/D and 3rd gear? If I pick up my foot everything smooths out once engine speed is below 3000rpm. Even had a loud backfire once and saw a cloud of black smoke in my mirror. Was driving on cruise control the other day at 60 mph, the road became a steep uphill, and when the cruise control tried to keep speed and downshift the same problems occurred.
Any ideas on where to start looking. No check engine light came on. Transfluid appears to be in the normal range. Just came back from a vacation trip, 1200 miles in the last week. No other problems except for this one.

Welcome to the forum!

It sounds like you have a misfire occuring at high rpm. I suspect that your 2003 Taurus has coil packs and distributorless ignition. Since the wires are relatively new along with the plugs, I'd suggest you start by making sure the plug wires are seated securely on the spark plugs. If that's fine, you may want to add a bottle of fuel injector cleaner to the fuel tank and see if after 100 miles or so there's any improvement. If not, then you may have a coil that is causing a misfire.

If you have access to a scan tool with a datastream mode you could monitor the oxygen sensor voltages on both cylinder banks to see if one goes lean or rich when the misfire occurs. That could help you determine if the problem is fuel or spark related. You could also check the long term and short term fuel trim readings.

-Rod

I've tried the fuel injector cleaner and actually had the fuel filter replaced again at 116K miles when I brought it back to the dealer for a 4-wheel alignment and 4 new tires ( only Wal-mart could beat the dealers prices on tires, and that included checking Tire-Rack and using a local installer, and all the "name" brand shops).
Tonight I will try to sneak the car up to 90 mph. I'm pretty sure that I can smoothly accelerate through the gears. Once I'm in OD I'm pretty sure I can raise rpms to over 3500 will no issues. So I would tend to rule out ignition, coil, wire issues. Of course I'm a scientist not a mechanic so I could be wrong. The problem I have is when the transmission "kicks down" a gear to accelerate. It's almost like it jumps from O/D to 2nd causing the rpms to go from 2100 to 3500 at which it like a rev limiter cuts the ignition, so now theres no load on the trans so it switches back to O/D revs drop to 3000, then trans kicks back down to 2nd and the process just keeps repeating itself until I lift off the gas. Of course the process I just described happens repeatably in the course of seconds, so the car jerks and jumps as the tranny gets loaded up in a low gear to high rpms. If I had to guess I would think that this is somehow related to a sensor ( mechanical or electronic ) that controls the transmission. but I'm just a backyard mechanic who fights to keep my 89 Bronco running. I'll take the Taurus to Autozone tonight and see if they can run the codes for me. Maybe some were set even though the check engine light never came on. I'll post more info tomorrow. Thanks for your reply. I should head over to the Bronco forum, I could probably help someone over there since I've kept mine running for close to 160K miles. Heck I just changed the original water pump at 159K miles, that might just be a record.:tongue: I'm not bringing it to dealer because if it is going to be a major repair, I'll probably just trade it in a Fusion.

You could have something as simple as a shaft speed sensor acting up in the transmission if it is really shifting and you're not experiencing a misfire. The PCM monitors the input and output shaft speed sensors to determine if the transmission is in the correct gear ratio for the other engine and load conditions. If one of these sensors is bad, it may not trip an powertrain code which the Autozone code readers read. Instead it would probably trigger a transmission code which requires a professional scan tool to read.

-Rod

So it may require a trip to the dealer after all if it is these shaft speed sensors.

On the ride home I slowly eased the rpm's higher. Got a stumble at 3500rpm, then another stumble, then smooth from 3600 to 3800rpm where it held steady, funny thing was cars were still passing me and I was near 85 mph.

I read in a different thread about the speedo and radio not working when the engine seems to stumble/misefire. Didn't have any speedo issues, and when listening to FM stations no radio problems. I slowed down and repeated the process tuned to an AM station and right at 3500rpm when the stumble/hesitation occurs there was a load "electronic noise" picked up by the radio, the noise occurred anytime the engine stumbled.

So maybe the issue is in the ignition, and the transmission responds to the misses so erratically shifting gears as the engine misses. I didn't make it to autozone last night will try to get there tonight to see if any codes were generated.