My low end torque sucks!!

[Cris_rrc]

Hey guys I got the 95 disco with the 3.9L auto , got the truck a month ago and been fixing some starting issues , at the beginning it had a running bad problem got fix with new cap ,rotor ,spark plugs and 8mm cables , idle got fix by cleaning the stepper motor , I ran Lucas complete fuel system in a full tank of super gasoline , but now the only problem that I still notice is low end torque very slow to get up speed ,I loose power on a long up hill (tractor trailers are passing me) and today I tried to got up a pile of dirt not a big deal and it would rev up but it didnt make ....has 76000 miles no check engine codes.
Any ideas ?? Im thinking checking the fuel injectors or maybe the cats are plug ?? but with 76000 miles I dont know

 

[Roving Beetle]

Throttle position sensor possibly. Or MAF sensor - or both.

Clogged cats would be more likely noticed at higher RPM's and speeds.

Low fuel pressure could be an issue too. Easy to test.

 

[Roving Beetle]

Oh - and are you sure it's the motor and not trans slipping or torque converter slip?

 

[Cris_rrc]

Oh - and are you sure it's the motor and not trans slipping or torque converter slip?

I dont feel nothing slipping everything feels fine other than low torque one you pass like 40 to 50 mph is all good will cruise at 75mph all day just dont loose any speed

 

[crown14]

Well test the backpressure before and after the cats to see if they are clogged... OR disconnect them from the engine and see if you notice it running better. Just dont catch your truck on fire.

 

[singingcamel]

Timing, i'd play with the timing ,try retarding it and see what happens.

 

[Cris_rrc]

Timing, i'd play with the timing ,try retarding it and see what happens.

Yeah that was one of my suspects , or fuel pressure / clog fuel injectors I dont think cats because while at idle if I rev it up I dont feel any problems

 

[jims95]

Check the vacuum advance unit on the outside of the distributor.

It is easy to check with the engine running, using a timing light and vacuum pump (Miti-vac).

 

[jims95]

Also, check the mechanical advance mechanism inside the distributor

With the distributor cap off, twist the rotor, and see if it springs back.

If not, the advance mechanism could be frozen and/or the advance weight springs fell off.

 

[pdxrovermech]

did you leave a rag sitting around the air box? seen it enough times to throw it out there.

 

[riceybean]

Or a pack rat that filled your airbox with seeds, happened to me.

 

[singingcamel]

If your running big tires , lift and a rack get use to it.

 

[Cris_rrc]

Well nothing clogging the air filter , I cleaned the MAF and throttle position sensor and nothing no change , also found that nipple in the distributor vaccum unit uncap , I remember that on another 3.9 I had that thing had a rubber cap so I just tape over it and nothing no change , been busy at work so doing stuff very slowly next is checking fuel pressure I do smell a little raw fuel smell coming from the tail pipe , after that I'll mess with timing but I dont have a timing light so I guess I'll find the TDC and play it by ear , will also check injectors in the pass I had good pressure but injectors were clog while talking about injectors had read about using mustang injectors are they really better ?? Ohhh Im running 255/70/16 MTRs with a rack but this is my 8th rover and never had an engine this low on power , I also have a D2 and it feels like a sports car compare to this D1

 

[singingcamel]

mY D1 has 140k,2" lift ,275 75 16 and its a dog uphill, I feel your pain on the long hills ,but you'd think with that mileage it ought to run right up.
lets us know what you find.
I'm thinking about doing a compression check on my 95.

 

[riceybean]

Sounds like my 95 when the advance on the dist went out. I was at 5000ft as well and could really tell there was something wrong when it went.

 

[cupgt]

My D1 is on 33s, RTE bumper, SD rack, and 2" lift. Its pretty bad on hills but on flat ground its not terrible. Have you compression tested it?

 

[cosmic88]

.... also found that nipple in the distributor vaccum unit uncap , I remember that on another 3.9 I had that thing had a rubber cap so I just tape over it and nothing no change.....

On many models (most I think) of vac advance module, there are two vacuum line ports. One on each side of the diaphram housing. you only want one of the ports to be covered with a plug and the other one needs to have a vacuum line leading back up to the intake plenum. Not that the unused port really needs to be plugged for running purposes, but it is good to keep airborne shit out of the diaphram housing. The port farthest away from the distrubutor cap is the one you need to have connected to the plenum... with higher plenum depression it "pulls" the diaphram linkage...



On your truck is there a vac line leading forward and away from the plenum or is that nipple capped off too? Without that line you have no advance of timing...



...

 

[Cris_rrc]

Thank you guys for all the help well this is what I did , got the #1 cylinder spark plug out got a screw driver in and I turned the engine by hand until TDC after that set the distributor to #1 started the truck and it felt the same , so I moved the degrees clockwise and truck feels like is going to stall , counter clockwise and feels like more power by revs go up so adjusted the idle went for a test drive and is like night and day really goes up hills no problem , the only wrong thing I notice is a ticking sounds valve tapping kind of noise , how ever the next day drove the truck on the highway 14 miles out of the house and my engine temp goes right up , pulled over my coolent is boiling white smoke from the coolent touching the hot engine and exhaust manifold , let it cool down and got it towed home , refill and found the leak coming from the intake manifold gasket , got the gasket today and planning in doing the job this wekend

 

[Jimmy]

Buy or borrow a timing light and get the timing right.

 

[Cris_rrc]

Final report , the timing was wrong and making the truck run like crap ,plus I was the new black distributor cap for the used Lucas blue one and just ran all day so much better ,thanks to all for the advise and help