Can't get it up...over hills

2003 Taurus, 66K. Between 35-45, very difficult getting over any kind of hill. Engine lugs, but doesn’t quite cut out. Have replaced crankcase vent hoses,upper intake gasket, PCV valve,hose, crankshaft pos. sensor. Have done all the service & maint. previous owner never did. No CEL, no codes. No one can figure out the cause.

Time to check for exhaust restrictions, or plugged catalytic converter.

I would also check fuel filter and fuel pump’ also spark plugs.

From what you say, this car must have been completely neglected by the previous owner.

Why doesn’t it downshift into a lower gear?

New fuel pump & filter installed 2/10. Iridium plugs installed 10/09. I’ve only put 10K on the car in the year I’ve had it. You’re correct, previous owner didn’t do anything except safety check and oil changes. I’ve done 6 yrs of maintenance in the past year !

Don’t know why! Tranny is good, fluids are good. Other than this problem on hills, it runs great.

New fuel pump & filter or not have the fuel pressure checked, especially under load. If you have to, then get a gauge rigged up while you drive. (A recent poster with a similar kind of problem kept ignoring advice to check the pressure on the basis that pump & filter had been replaced. He chased his tail and spent a lot of $$ for a couple of weeks and finally found his new fuel filter to be plugged. Its a simple thing to check so there’s no reason not to).

You should also get a vacuum gauge on it to check for exhaust restriction as Docnick originally mentioned.

I’d also drop the fancy plugs and just get standard OEM plugs in there.

You mean on a hill, you push the gas all the way down to the floor and the trans does not downshift? If yes is the answer you have a transmission problem.

On hills the motor needs to have some rpm’s to go up the hill. A downshift should put the rpm’s in the 3,000 range and give you plenty of power. If pushing down on the gas petal doesn’t force a downshift you can move the shifter from “D” to “3” and see what happens. Don’t be afraid to push down on the gas. Your motor can “roar” and make lots of noise and it won’t hurt it. It can handle rpm’s of 5,500 to 6,000 rpm if necessary to deal with loads and hills.

Could also be a problem with the torque converter lockup.

The only way I can describe it is that it lugs. Once I’m up to 40-45, it’s fine.
Next time this happens I’ll keep tabs on the RPMs to see what it’s doing. Found a possible good mechanic locally and will have him check it out.

The auto transmission should downshift before the motor “lugs”. You have a problem with the transmission most likely. Having it looked at by your mechanic is your best move now.

Found the problem ! Coil pack was cracked in 3 places. Have started taking the car to a local mechanic recommended here on Car Talk. He found it and fixed it for a very reasonable price ! She runs like a brand new car now and we can get up over hills !

Many thanks to all of you for your input and advice!