No Power past 2500/3000 RPMs

[kman1231]

I have a 99 ford explorer that has no power past 2500 Rpms. It stumbles and pops and just doesnt go. Good luck trying to climb any kinda of a hill. It drives fine under and shifts like it should and it will get to freeway speeds slowly. I have tryed to fix it my self but have not had any success. So far i have replaced, Upper o2's left and right, MAF, Intake gaskets and fuel rail gaskets, EGR Valve, Spark plugs,wires, Fuel pressure regulator, Fuel filters. i am sure i did more i just cant think right now. i have about 65 pounds of fuel pressure at the rail. My spark advance is at 18 at idle and 30-35 at 2-3k rpms. I don't know where else to look. Please help.

 

[swshawaii]

Trouble codes? :scratch:

 

[kman1231]

no codes
It had a P0174 but no more

 

[2000StreetRod]

which engine?

There are three different engines possible in 1999.
Have you performed any modifications?
The fuel pressure is fine. Have you measured compression?

 

[kman1231]

Srry Its the 4.0 Ohv and the compression is normal. The motor is all stock.

 

[2000StreetRod]

PIDs

Have you checked the inlet filter and main intake tube for mouse nests and packed snow?

Are you using some type of scan tool to read the spark advance?

If so, what are your long and short term fuel trims at cruise?

Does your TPS read normal from idle to WOT? See Ford Explorer - Ranger TPS Test Procedure
You can also read the PID "TP throttle position" with your scanner.

Have you checked for an exhaust flow restriction (i.e. potato jammed in tailpipe, bent tailpipe, failed cat, etc.)?

Will the vehicle accelerate rapidly from stop up to 2500 rpm with the accelerator at mid-range?

 

[alohamonte]

Find a buddy for 5 minutes. Take off the intake snorkle so you can see the throttle body. you dont need to even start the car for this. have your buddy sit in the drivers seat and push the pedal to the metal. look inside the throttle body. see if the fly is opening all the way. it should be completely horizontal. if it's not, then you have too much slack in throttle cable. you can remove that slack by adjusting the cable at the pedal. for me, I had a ton of slack, made the adjustment, and it feel like I had a new engine.

 

[koda2000]

I had this happen once with a Chrysler V6 min-van. In my case, it turned out to be a plate had come loose inside the muffler and was blocking the outlet. It ran fine at idle, would move under it's own power, but if you tried to give it the gas it just had no power. It would barely climb my driveway, which was about 25-30 degrees incline. Cheap-ass Midas muffler.

 

[bill06447]

Plugged cat.

Bill

 

[kman1231]

i will have to check the tps readings tomorrow as well as seeing if the throttle body is fully opeing. i did remove the back cat off the y pipe. it was sure loud but no power gain. There is 2 more further up but thats were the o2 sensors are and its impossible to get to . How can i test them?