Mysterious loss of power during acceleration/uphill

[jaronpham]

So...I can't say I'm advanced in my automotive mechanical skills, but I know enough to tackle projects w the help of youtube/forums.

I just tackled the replacement of my slave cylinder, everything went swimmingly and while I was down there I took the time to replace the clutch plate and pressure plate as well. Reassembly went well, we had to remove the exhaust and transfer case in the process and those went back into place smoothly.

The clutch feels much better, we removed the master cylinder as well and did a full bleed of the whole system.

Took it for drive, everything seemed fine UNTIL I attempted to accelerate while driving up a hill. Suddenly, there was a loss of power and no to minimal acceleration.

Initially I assumed that the new clutch was slipping and I mustve done something wrong during reassembly. After further observation, I believe it's safe to rule out clutch slippage. The RPM refuses to rise, and the engine itself seems to be losing power under certain load.

I checked MAF - seems clean and working. Checked air filter, seems clean. Them I found a small gash in air intake duct that that been previously repaired but seemed to have opened back up while we were working around it. Sealed that back up and expected the problem to be fixed. Nada.

I can't figure this out!! Any ideas??

Thank you

 

[RonD]

Welcome to TRS

So the 1993 4.0l was running fine until the new clutch?

If so only thing that comes to mind is exhaust blockage or O2 sensor issue

The plugins for O2 sensors are close together on the main 4.0l wiring harness and there is a Right and Left to computer, only 1 wire color difference between the 2
But if reversed the engine would run poorly after warm up not just uphill
Check for wires between bell housing and engine, its easy to pinch a wire when reinstalling a transmission, just run your hand along the seam at the to to make sure

An engine is a self powered AIR PUMP, if air flow is restricted IN that limits RPMs, obviously the throttle plate comes to mind, lol
And if air flow is restricted OUT same thing, limited RPMs
You did remove the exhaust

You can use a Vacuum gauge to determine limited air flow on any gasoline engine

 

[rusty ol ranger]

Sounds like a plugged cat.

 

[jaronpham]

disconnected the exhaust before the cat, ran the vehicle. same issue...

 

[jaronpham]

Welcome to TRS

So the 1993 4.0l was running fine until the new clutch?

If so only thing that comes to mind is exhaust blockage or O2 sensor issue

The plugins for O2 sensors are close together on the main 4.0l wiring harness and there is a Right and Left to computer, only 1 wire color difference between the 2
But if reversed the engine would run poorly after warm up not just uphill
Check for wires between bell housing and engine, its easy to pinch a wire when reinstalling a transmission, just run your hand along the seam at the to to make sure

An engine is a self powered AIR PUMP, if air flow is restricted IN that limits RPMs, obviously the throttle plate comes to mind, lol
And if air flow is restricted OUT same thing, limited RPMs
You did remove the exhaust

You can use a Vacuum gauge to determine limited air flow on any gasoline engine

Thanks for in depth response! I will check the in flow and outflow and bellhousing and keep you posted

 

[jaronpham]

Ok. Bear with me here.

I narrowed down the problem to the Vehicle speed sensor on the transfer case. My brother was helping me and I believe he accidentally reattached the wiring harness to a connector on the transmission extension housing. I realized this, swapped the wiring harness to its correct position, reset the PCM, and voila it was working no issues.

Then...the engine still seemed louder than before, and I saw that I hadn't fastened down one of the exhaust manifolds all the way. I adjusted it, went to start the truck and it wouldnt start. It cranks but wont turn over.

I'm at a loss and some weird electrical issues are happening now. For instance, the headlights are always on now. I can't turn them off without taking the fuse out or disconnecting the battery.

Help! This is turned into a nightmare and is way beyond my paygrade

 

[Tideaz]

Any answers?

 

[Ranger850]

Make sure no wires were pinched at the exhaust manifold.

 

[jaronpham]

No wires pinched. I'm assuming that somewhere that headlamp circuit is drawing power and restricting power to fuel system? I just can't find the headlamp relay to see if its malfunctioning.

 

[RonD]

No relays for headlights in any year Ranger

High Beam Headlight's 12volts come from fuse 12 in the cab, if that's the one you pull out then issue is in the Multi-function switch(turn signal stalk)

Flash to Pass has 12volts all the time, check the stalk make sure its not pushed forward, High Beams ON

Main light switch is powered by fuse 2 in the Engine Bay fuse box
It only powers headlights when its turned on
So if you are pulling out fuse 2 to power off head lights then Main Light switch is bad

1993/4 wiring is the same