Howdy,

My 2002 Ford Explorer XLT 4.6L V8 has no power after an engine and transmisson rebuild. Is it the Engine or Transmission????

OPERATION:
The explorer seems normal but has no power. I have to feather the accelerator around 2Krpm so the automatic transmission can shift into different gears. the RPMs jump up to 3-4Krpm as soon as it shifts. It will only get up to 65-70mph then it bogs down and hesitates like the old UHAUL trucks that had governors on them for 55mph.

TESTS/RESULTS:
Idles good enough@~800rpm, never stalls.
Compression is ~125psi in each cylinder.
Fuel pressure normal at idle and holds at least 30 minutes after shutdown.
New fuel filter, checked regulator.
Timing between the crank and cam(s) has been physically verified.
Cams and Valves look OK (with covers off).
Vacuum at the throttle body brake port is normal at 22hg.
Back pressure is OK at less than 2.5psi @ 2.5Krpm (tested @EGR pipe).
Sensors MAF, IAC, EGR, throttle pot all test normal.
PCV valve replaced and most vacuum hose parts.
Brake booster check valve is good.
all gauges read normal (nothing hot)
It even passed a smog test with normal readings.

CODES:
Occasionally three codes show up; 0305. 0306, & 0171 (cylinder 5 & 6 misfire & lean right cylinder bank) I have replaced those coils, later I swapped several coils around but it still comes on infrequently after 20 minutes on the freeway. I can slooowly get my speed up to ~65mph but it is just inertia---I can't pass anyone or go faster then 65mph. It seems to work reasonably well from 0-20mph but I have to feather it for the tranny to shift out of first. Hills and overpasses are a steady crawl unless I've built up some speed.

ENGINE REBUILD HISTORY:
I used a local machine shop to rebuild my 4.6L V8 engine (timing guides/chain went at 86K). I have been fixing/replacing everything from a loose bolt on the harmonic balancer to recycled gaskets that this bozo did incorrectly. I pulled the Timing cover and checked the timing, it was correct, however I did notice that he had put the Reluctor gear in backwards once then put it in correctly. There is a distinct pattern etched into the timing cover which could only come from the back of the reluctor wheel. The wheel is a thin pressed gear with the word "Front" on the teeth side. The crank gear looks correct for this thin reluctor wheel. The loose harmonic balancer/crank pulley caused the reluctor wheel to wobble and it is now slightly scored from the right timing chain, it still looked functional so I left it in. The right timing chain is very tight but the left chain has some slack as it comes off the bottom of the crank gear and also onto the Cam gear- I retightened the guides but there is still a little slack in the left chain.

The only item left is to pull the pan and maybe I can see if he used the wrong engine parts to rebuild with. The 2002 explorer (02/2002)supposedly has different/heavier parts than other years.

I also had the transmission rebuilt the week after the engine.
Are there any transmission sensors or feedback issues to the computers (PCM) that might cause a lack of power in the engine???? Torque converter issues??

Thanks any advice

Mike

 

125 PSI sounds very low to me. Was the throttle wide open during the test? My Ranger's 23 year old 2.9 V6 still has 160 PSI on all 6 cylinders, and its a fairly low compression engine that has never been rebuilt.

Those loud metallic clicking noises sounds like pinging/knocking to me. Your lean codes also support that theory.

I'd start by checking the MAF, throttle position sensor and the coolant temperature sensor. You may also want to try replacing the O2 sensors. If that still doesn't solve your problem, you may want to have your fuel injectors cleaned/flow tested and the fuel pump tested as well.

If you can figure out some way you can still close the hood but route a fuel pressure gauge outside, like taped to the windshield it may be worth it to see if under load your fuel pressure is dropping off.

 

Agreed the problem sounds like pinging. Check that the injectors are wired correctly, the injector connectors are numbered but it's easy to reverse a pair if not paying attention.

 

Thanks for the response, As you can see my post I have already checked the MAF,TPS, O2, & fuel pressure. I put a pressure gauge on the fuel rail and the pressure remains constant during operation.

The injector wiring on the PCM cable (on the 2002 explorer) is fixed/wrapped in position, there is no way to mix up the connections.

Considering possible engine rebuild issues. 125psi in all 8 cylinders seems reasonable to me, my Bronco II had the same compression in it's V6 cylinders when it was brand new (and for many years). Any mechanics out there who have dealt with a lot of the 4.6L V8 engines?? Should it be higher??

Any suggestions?? I am now leaning towards transmission rebuild issues as a cause. The Transmission seems to shift only at 2Krpm, any higher RPM and the engine whines out, then kind of bogs down with a machine gun type rattle. The rpms jump up past 3Krpm immediately once the trannsmission shifts gears. It will not go faster then 65-70 mph and it starts to "hesitate" at that speed like the old Uhaul trucks that had governers on them for 55mph.

Thanks again for the suggestions--

 

The rattle sounds like knocking to me. You have a fueling problem, that is apparent enough with the lean codes. When an engine is lean it will knock and bog as you describe. It seems to me that at higher RPMs your computer is either de-fueling or your fuel pressure is dropping off.

The transmission doesn't control shifting, a computer does. I'm not sure if your model year has a separate transmission control computer, or if its all integrated into one unit with the engine computer.

A video would be helpful too I think.