Power Loss

beamacvt

beamacvt

Well-known member
May 1, 2010
73
0
Virginia
Edit - 2003 Disco II - 77,000 miles

So... take my Disco offroad this past weekend...

First STEEP incline (steep enough to get front wheels hovering a little) - get halfway up and lose power... felt like the engine was just bogging down and wasn't able to pull me up... thought it could have been transmission issue at first so I tried it in reverse - made it right up... no power loss...

The more I thought about it, transmission nor transfer case made any sense for this type of problem, but what do I know...

I continued to attempt the hill with ABS unhooked thinking it was somehow braking all of my wheels (have Tru-Trac in front, Detroit in rear and CDL)... but no go. I had ample oil pressure the entire time.

I was also experiencing a popping from within the engine compartment when the gas pedal was close to the floor.

So a long shot, thought it could be blocked exhaust... Nope - first of all no codes and second had cats checked yesterday at muffler shop and they are good to go...

My last ditch effort will be to put in a new fuel pump, but I don't really have steep enough hills around here to truly check it until I get off road again.

Any thoughts out there before I start pulling the carpet?? I feel it's more of a pain in the rear to get to the valve to check the pressure than it is to just pull the pump assembly and replace the pump. I can then check the filter for debris at the same time.

It was mentioned over at LRF the possibility of the torque converter, clutch or low transmission fluid.

I will check the trans fluid and run a small torque converter test this evening to possibly eliminate those to options, but I am not experiencing any trans slip on normal road conditions.... so would the clutch be showing any other symptoms than just on extreme grades?
 
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beamacvt

beamacvt

Well-known member
May 1, 2010
73
0
Virginia
I had a full tank... it dropped to 3/4 tank by the end of the day.

Would the torque converter work in reverse and not drive?
 
Roving Beetle

Roving Beetle

Well-known member
Nov 11, 2007
4,823
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Mount Desert Island, Maine
www.desertboat.com
Did you verify the truck was going into low/1rst gear in fwd? It sounds like if it made it in reverse but not drive then it's a trans issue. Something is keeping it from going down into 1-2?

The popping may have been the engine being "lugged" down down by too high gearing and causing pre-detenation.

Did the lights on the dash indicate it goes into low gear "1" when you pull the lever all the way back? They can get out of adjustment.... but it still "should" kick into low gear if you lug it enough. ????

If it goes in reverse fine it's not the torque converter. It could be a low trans fluid issue or a fuel starvation issue (which sound VERY unlikely to me by the way)

EDIT: How does it drive out on the road from a standing start? Seem like it's holding 1-2 gears OK and takes off from a stop light fine? In other words are all the gears functioning well? Plenty of power day to day getting onto the throttle hard?
 
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beamacvt

beamacvt

Well-known member
May 1, 2010
73
0
Virginia
That's a great point... I never tried to manually put it in first gear when climbing... I always just assumed it was down shifting in to first on its own. I can't imagine it left first or at most second given the trails I was on.

I did manually put it in first several times when travelling down steep grades and it functioned the way I would expect it to.

Daily driving is great... the transmission has never given me a slip or any signs of failure. It has plenty of power and no hesitation when getting on the throttle.
 
wheelen disco

wheelen disco

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Jun 20, 2010
1,089
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rice lake Wisconsin
When the t case was in low did you press the mode button? If so it may have been in manual mode, it doesn't shift (and the M is illuminated on your dash) so if you put it in drive it just stays in 4th gear
 
beamacvt

beamacvt

Well-known member
May 1, 2010
73
0
Virginia
I didn't have the mode button pushed at least the light was not illuminated on my dash. But that makes perfect sense, and would be very fitting to my symptoms.

Is there a circumstance with the tranny would remain in 4th without the mode button? low fluid etc?
 
mbrummal

mbrummal

Well-known member
Jan 23, 2009
2,895
22
Willow Spring, NC
It will stay in the gear you selected except to keep the engine from stalling. It will down shift if you start going up a steep incline, especially at full throttle. That was probably not the problem.
 
beamacvt

beamacvt

Well-known member
May 1, 2010
73
0
Virginia
So that leads me to believe it is still possible the transmission was not down shifting properly... which seems logical to me.
 
beamacvt

beamacvt

Well-known member
May 1, 2010
73
0
Virginia
I hope you are right...

I'll let you guys know what I find tonight as far as tranny fluid level, color, smell etc are concerned.
 
beamacvt

beamacvt

Well-known member
May 1, 2010
73
0
Virginia
99% sure I found the culprit tonight...

A sizable gap in the intake hose where it meets the upper plenum (about 2-3 inches)... when car was traveling up hill it made the gap larger, but when pressure was forcing it down made the gap smaller...

The upper plenum was gulping air but starving itself of fuel. :banghead:


Hopefully that is problem solved... I'll put it to the test this weekend.

On a side note... tranny fluid level was good and looked like new.
 
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