I bought an 02 WJ 4.7 4x4 limited with a bad engine. After 2 months of searching, I bought a complete 01 WJ 4.7 2wd Monday of this week. It had been T-boned in the side, and I got it cheap. The damage was minimal enough that I was able to drive it 1.5hrs home. The thing was a beast... had TONS of power and ran great.

Pulled the motor from the wrecked one, and installed it into mine today. Here comes the problems....

it runs great when you crank it. But when you put it in gear it will take off and then fall on its face, like its starving for fuel. It has thrown 2 codes, P0171 (system too lean, bank 1) and P0174 (system too lean, bank 2). Sometimes it will start puttering, and lose rpms until it dies. Took 10mins to get it to crank back up earlier.

The fuel pump has less than 10 miles on it. I did not change any sensors during the engine swap except the MAP sensor, due to the harness plug being different. I know that the gas was bad, but I have added a bottle of "heet" and a bottle of lucas octane boost along with a premium fillup.

I dont understand what could have caused the great running engine to all of a sudden have issues... any ideas???

I bought an 02 WJ 4.7 4x4 limited with a bad engine. After 2 months of searching, I bought a complete 01 WJ 4.7 2wd Monday of this week. It had been T-boned in the side, and I got it cheap. The damage was minimal enough that I was able to drive it 1.5hrs home. The thing was a beast... had TONS of power and ran great.

Pulled the motor from the wrecked one, and installed it into mine today. Here comes the problems....

it runs great when you crank it. But when you put it in gear it will take off and then fall on its face, like its starving for fuel. It has thrown 2 codes, P0171 (system too lean, bank 1) and P0174 (system too lean, bank 2). Sometimes it will start puttering, and lose rpms until it dies. Took 10mins to get it to crank back up earlier.

The fuel pump has less than 10 miles on it. I did not change any sensors during the engine swap except the MAP sensor, due to the harness plug being different. I know that the gas was bad, but I have added a bottle of "heet" and a bottle of lucas octane boost along with a premium fillup.

I dont understand what could have caused the great running engine to all of a sudden have issues... any ideas???

Fuel Pump has less than 10 miles on it?
Did you replace the fuel pump with a new one?
Do a fuel pressure check at the fuel rail to make sure that a line didn't get pinched or something plugged during the swap.
Then at least you will know that it has good fuel pressure to the injectors and you can look elsewhere.
Were the problems there before you added the Heet & Octane boost or after?

You hit it right on the head... Hooked a fuel pressure gauge to the rail yesterday, and sure enough, when it started acting up the fuel psi went from 54 to 14. I installed the pump the day I bought the jeep, only to find out the engine knocked. Swapped in a new pump, now it runs like a champ! Thanks for the reply man!

You hit it right on the head... Hooked a fuel pressure gauge to the rail yesterday, and sure enough, when it started acting up the fuel psi went from 54 to 14. I installed the pump the day I bought the jeep, only to find out the engine knocked. Swapped in a new pump, now it runs like a champ! Thanks for the reply man!

You mean I got one right?
Even a blind squirrel finds a nut once in a while. :-)

You mean I got one right?
Even a blind squirrel finds a nut once in a while. :-)
Nice!