[Bigmant773]

Does this sound normal to everyone? The reason I ask, is because over the last three weeks while my disco was sitting as I waited for my parts to arrive, I was borrowing the grandparents minivan.... and it has way more acceleration, power and overall get up and go then the disco has.

I’m talking like getting it up to highway speeds takes longer than a vehicle should take. When I go up a steep grade, I am lucky to maintain the same speed even with the RPMs screaming above 3000.

Does this sound normal for this old girl, or is there something I can check?

 

[sierrafery]

Can't hurt to put a new air filter and clean the MAF sensor with dedicated spray, eventually put some good brand injector cleaner in the fuel, one of these The Best Fuel Injector Cleaners For Your Car @ Top Speed

though if you have much bigger than standard tyres it's normal to have less power

 

[reverendALC]

If it makes you feel any better, my 94 RRC has the 4.4 and runs great, but is the slowest most sluggish LR I’ve ever owned

 

[Bigmant773]

If it makes you feel any better, my 94 RRC has the 4.4 and runs great, but is the slowest most sluggish LR I’ve ever owned

It makes me feel slightly better haha. But not much. It just seems absurd that these vehicles have such low power.

 

[Bigmant773]

Can't hurt to put a new air filter and clean the MAF sensor with dedicated spray, eventually put some good brand injector cleaner in the fuel, one of these The Best Fuel Injector Cleaners For Your Car @ Top Speed

though if you have much bigger than standard tyres it's normal to have less power

Standard tires, new air filter, new maf sensor, new spark plugs, new wires. The car is as cleaned up as it can be. Just wanted to make sure there wasn’t something I missed! The injector cleaner might be worth looking into though, I’ll give it a shot.

 

[sierrafery]

A well running Thor should not be so sluggish though, how sure are you about the fuel pressure regulator or even the pump? if it wasnt ever changed might worth a try to replace it with new or at least measure the pressure cos a ''tired'' regulator can open at lower pressure which can affect the engine power... is your's manual or auto ?

from the WSM:
Fuel pressure regulator
The fuel pressure regulator is located in the underside of the top cover. The regulator is sealed with two 'O' rings and retained with a clip.
The regulator is connected to the fuel feed pipe at the top of the pump housing and maintains the fuel pump delivery pressure to 3.5 bar (50 lbf.in2). When the fuel delivery pressure exceeds 3.5 bar (50 lbf.in2), the regulator opens and
relieves excess pressure back to the swirl pot via a return pipe. The regulator ensures that the fuel rails and injectors are supplied with a constant pressure.
The fuel pump delivery pressure and pressure regulator operating pressure can be checked using a Schraeder type valve located at the rear of the engine on the fuel rail. The valve allows the pump delivery pressure to be measured using a suitable gauge and an adaptor and hose which are special tools.

 

[Bigmant773]

A well running Thor should not be so sluggish though, how sure are you about the fuel pressure regulator or even the pump? if it wasnt ever changed might worth a try to replace it with new or at least measure the pressure cos a ''tired'' regulator can open at lower pressure which can affect the engine power... is your's manual or auto ?

from the WSM:
Fuel pressure regulator
The fuel pressure regulator is located in the underside of the top cover. The regulator is sealed with two 'O' rings and retained with a clip.
The regulator is connected to the fuel feed pipe at the top of the pump housing and maintains the fuel pump delivery pressure to 3.5 bar (50 lbf.in2). When the fuel delivery pressure exceeds 3.5 bar (50 lbf.in2), the regulator opens and
relieves excess pressure back to the swirl pot via a return pipe. The regulator ensures that the fuel rails and injectors are supplied with a constant pressure.
The fuel pump delivery pressure and pressure regulator operating pressure can be checked using a Schraeder type valve located at the rear of the engine on the fuel rail. The valve allows the pump delivery pressure to be measured using a suitable gauge and an adaptor and hose which are special tools.

I am not sure about the fuel pump, but I can’t imagine it’s ever been done. Would a bad fuel pump cause these low power issues?? The truck is an auto btw.

 

[Bigmant773]

Does the 4.6 even have a fuel regulator though? I thought that was just a diesel thing. For the 4.6 isn’t it just a fuel pump?

 

[Bigmant773]

Does anyone think this could be an O2 sensor issue, even though I am not throwing any O2 sensor codes?

 

[sierrafery]

Run a stall test on it which will reveal if it's low engine power, unporper fuel pressure can cause that without doubt

As about the FPR, this pic is from NAS D2 WSM and the description of the regulator in my previous post was from there too but i didnt remove such pump myself to confirm, the part is available as ETC8494

 

[Bigmant773]

Run a stall test on it which will reveal if it's low engine power, unporper fuel pressure can cause that without doubt

View attachment 92651

As about the FPR, this pic is from NAS D2 WSM and the description of the regulator in my previous post was from there too but i didnt remove such pump myself to confirm, the part is available as ETC8494

View attachment 92652

Ok so I did the test once warmed up and no longer for 10 seconds as directed, and it’ll go up to 2000 rpm and hold there. So there is a loss of engine power somewhere. Useful test to say the least! I think that means we’ve narrowed it down to something engine/power related

 

[sierrafery]

I was kinda expecting that based on your first post, you'll have to investigate why and fix it then you'll see that the Thor is quite powerfull once it works well. Unfortunately i can't guess what's the reason, seems a fuelling issue to me

 

[JUKE179r]

Are you getting any fault codes? Check your fuses in the engine bay (especially F2 15A fuse)?
Sounds more like bad/clogged injectors. Throw some Berryman's B-12 or BG 44K injector cleaner in the fuel tank, run it around and see what happens.

BTW... check your throttle position sensor connector isn't loose at the throttle.

Also... remove and clean the spiral oil separator in the RH rocker cover. IMHO, I'd remove the oil separator, chuck it and the black plastic barb connector in the garbage and insert a proper metal PCV valve into the rear of the intake manifold...
Step #1 Purchase the FV308 PCV from either Rock Auto, Ebay, or your local parts store.
Step #2 Disconnect the clamp holding the breather hose onto the OEM Black Plastic Nipple (mounted on the intake).
Step #3 Remove the breather hose and then using a 14mm box end wrench remove the OEM Black Plastic Nipple.
Step #4 Thread the FV308 into place, and re-install the breather hose and breather hose clamp.
Step #5 Remove the breather hose clamp on the opposite end going to the RH valve cover and the breather hose.
Step #6 On 99-02 models spray a bit of carb spray into the hole to loosen it up, and then gently pull up and remove the OEM plastic baffle.
On 03-04 models you will actually have to remove the tube containing the OEM plastic baffle from the valve cover. I've had success with using electrical tape around the tube and then gently twisting it out. Once out remove the baffle and then drill out the hole at the end of the tube. Then re-install the tube into the valve cover. I use a 13mm socket, with a 6inch 3/8 extension to tap it back into place.
Step #7 Re-install the breather hose and hose clamp and you are done.

PCV part numbers...
Fram #FV308, Standard Motor Products #V288, #PCV308, NAPA #CRB29380, Sankei #KP111, Duralast #PCV147DL, AZ Filters #PCV1147DL, Purolator #PV1027, or Beck Arnley #045-0264

 

[Merlinbasenji]

Does this sound normal to everyone? The reason I ask, is because over the last three weeks while my disco was sitting as I waited for my parts to arrive, I was borrowing the grandparents minivan.... and it has way more acceleration, power and overall get up and go then the disco has.

All of the ideas shared are on the right path - another idea is to replace the injectors with new Bosch. This made a night and day difference in my 2000 D2. Even after many rounds of cleaner, old injectors just don’t atomize the fuel like new.

 

[Bigmant773]

I was kinda expecting that based on your first post, you'll have to investigate why and fix it then you'll see that the Thor is quite powerfull once it works well. Unfortunately i can't guess what's the reason, seems a fuelling issue to me

I agree, it seems like a fueling issue, like a weak pump or worn out injectors. I would love to replace the fuel pump, but I would hate to spend $300 on a guess. Although it would be way cheaper than the injectors haha

 

[Bigmant773]

Are you getting any fault codes? Check your fuses in the engine bay (especially F2 15A fuse)?
Sounds more like bad/clogged injectors. Throw some Berryman's B-12 or BG 44K injector cleaner in the fuel tank, run it around and see what happens.

BTW... check your throttle position sensor connector isn't loose at the throttle.

Also... remove and clean the spiral oil separator in the RH rocker cover. IMHO, I'd remove the oil separator, chuck it and the black plastic barb connector in the garbage and insert a proper metal PCV valve into the rear of the intake manifold...
Step #1 Purchase the FV308 PCV from either Rock Auto, Ebay, or your local parts store.
Step #2 Disconnect the clamp holding the breather hose onto the OEM Black Plastic Nipple (mounted on the intake).
Step #3 Remove the breather hose and then using a 14mm box end wrench remove the OEM Black Plastic Nipple.
Step #4 Thread the FV308 into place, and re-install the breather hose and breather hose clamp.
Step #5 Remove the breather hose clamp on the opposite end going to the RH valve cover and the breather hose.
Step #6 On 99-02 models spray a bit of carb spray into the hole to loosen it up, and then gently pull up and remove the OEM plastic baffle.
On 03-04 models you will actually have to remove the tube containing the OEM plastic baffle from the valve cover. I've had success with using electrical tape around the tube and then gently twisting it out. Once out remove the baffle and then drill out the hole at the end of the tube. Then re-install the tube into the valve cover. I use a 13mm socket, with a 6inch 3/8 extension to tap it back into place.
Step #7 Re-install the breather hose and hose clamp and you are done.

PCV part numbers...
Fram #FV308, Standard Motor Products #V288, #PCV308, NAPA #CRB29380, Sankei #KP111, Duralast #PCV147DL, AZ Filters #PCV1147DL, Purolator #PV1027, or Beck Arnley #045-0264

Ok, checked the fuses and all are good. Threw in some injector cleaner as well, so we’ll see how that works out.

I’ll keep that mod in mind! I don’t think that would cause the power issue, but something to do in the future for sure!

 

[Bigmant773]

All of the ideas shared are on the right path - another idea is to replace the injectors with new Bosch. This made a night and day difference in my 2000 D2. Even after many rounds of cleaner, old injectors just don’t atomize the fuel like new.

I would love to do this, but man theyre expensive! Like I said above, I’d love to narrow down what’s wrong before spending that kind of money.

 

[JUKE179r]

If you have to get a set of 8 Bosch injectors, I can vouch for this set from eBay seller “yourinjectorshop” out of Florida. I bought this set back in May for $78 but now they are $124...
Best Upgrade 4 Hole Bosch Land Rover 8x Fuel Injectors for 0280155787 4.0L 4.6L | eBay
My new injector vs. old...

Or
You can call around to ask about the pricing and detailed process of reconditioning your used set of injectors to save money.

My 19 year old engine runs a lot smother and better with the new injectors, new NGK plugs, Taylor 10mm leads, additional ground cables and 2 new igniter packs that I installed.


BTW... there was a Disco 2 owner on another forum who had backfiring and low power. All he did was tighten down the intake manifold bolts and reported that helped his engine problems.

 

[masantschi]

Or
You can call around to ask about the pricing and detailed process of reconditioning your used set of injectors to save money.

My 19 year old engine runs a lot smother and better with the new injectors, new NGK plugs, Taylor 10mm leads, additional ground cables and 2 new igniter packs that I installed.

Yeah - I rebuilt mine and can recognize a big difference.

Mike - why'd you add more grounding cables and where etc?

 

[JUKE179r]

I made two beefier 10AWG cables for the rear of the engine.
The first cable I installed in place of the webbed grounding strap that goes from the LH rear of the engine to the firewall. The old webbed grounding strap was badly corroded which is why I replaced it. I've seen the same corroded strap on other Disco 2's.
I added the second cable from the coil pack mount bolt to the same bolt at the firewall for better grounding of the coil pack.