Page 1 of 5 12345 LastLast
Results 1 to 10 of 44

Thread: Embarrassing lack of torque

  1. #1
    Join Date
    Mar 2013
    Location
    Canberra
    Posts
    285

    Embarrassing lack of torque

    Hi all,

    I've had my Rodeo (4JB1 2.8L turbo) for about 20 months now and can honestly say of the 15 or so cars I've ever owned, it is hands-down the most gutless of them all. I was on the Hume Highway just south of Sydney the other day and was nearly down to 3rd gear and 75 km/h on Catherine Hill and had a semi rapidly gaining on me in the slow vehicle lane! Pantecs regularly burn me off at the lights! It won't even spin the wheels in loose gravel……..

    It has always been a bit slow, but I think it is getting worse. I only put one tank of dino through it when I bought it, then straight to B100 and its been there ever since, so not a lot to compare fuel-wise, through I do recall it having more power and torque on dino. The lack of grunt is most notable on very hot days and I assumed it was just heat soak through the turbo and manifold as it has no intercooler, but I'm starting to wonder if it is something else. Cold weather is noticeably better power-wise, as it is for most turbo vehicles, but torque is still pretty bad. It is like the thing has a built-in hill detection unit…the slightest grade will shave the speed off and I regularly have to drop it down a cog or two on hills. It will easily do 130 - 140 km/h on the flat, but get a grade involved and I struggle to maintain 100. Some things I've already checked / considered:

    • Air filter is clean;
    • Fuel filter is new;
    • Doesn't blow much smoke except at idle on startup;
    • Uses no oil between 5,000 km changes, although I wonder if I am burning some and getting some dilution by fuel at the same rate?
    • It has 225,000km and the previous owner (from basically new) was a meticulous diesel mechanic who had full service history for it;
    • Injector pump was replaced about 12 months before I bought it;
    • I disconnected the crankcase vent running into the pre-turbo intake pipe and let it vent to air to save the turbo (pipework was surprisingly clean, though);
    • It has no EGR;
    • It has a full 2.5" exhaust from the turbo back, installed by the previous owner (I'd hate to see how it would go with the stock exhaust!);
    • It is running 11 PSI of boost stock from its tiny little turbo, but suffers from terrible lag below 2,500 RPM and runs out of revs by about 3,750 RPM - redline is about 4,100. You can get about 12 PSI out of it disconnecting the wastegate. Horespower feels like it doubles when it is on boost, but it doesn't have the torque to hold it in the right rev range when you hit any sort of a hill, even when you hit it in the maximum torque sweet-spot.
    • Fuel consumption was about 9.5L/100km on that first tank of dino and has been about 12L/100 km on B100 since.


    Any thoughts?

    3DB
    3DB
    1995 Holden (Isuzu) Rodeo 2.8TD 4X4 - B100 since April 2013
    1976 Mercedes 300D Turbo 'The Coal Grenade' - B100 since May 2016 - SOLD
    1994 Peugeot 405 SRDT 1.9L intercooled turbo diesel (Shitbox Rally car.) - B100 since August 2019 - SOLD
    @thirddegreeburns on Instagram
    @thirddegreeburns2019 on Facebook

  2. #2
    Join Date
    Sep 2005
    Location
    WA
    Posts
    4,372

    Re: Embarrassing lack of torque

    You state that the fuel filter is new.
    Is there only one fuel filter?
    No tank strainer or filter in the IP?
    Does it seem like fuel starvation?
    Any air in fuel lines when under load? (yes it would be hard to find out but can simulate this when stationary)
    Any starting difficulties?

    I hope we can help you.

    Tony
    Life is a journey, with problems to solve, lessons to learn, but most of all, experiences to enjoy.

    Current Vehicles in stable:
    '06 Musso Sports 4X4 Manual Crew Cab tray back.
    '04 Rexton 4X4 Automatic SUV
    '2014 Toyota Prius (on ULP) - Wife's car

    Previous Vehicles:
    '90 Mazda Capella. (2000 - 2003) My first Fatmobile. Converted to fun on veggie oil with a 2 tank setup.
    '80 Mercedes 300D. 2 tank conversion [Sold]
    '84 Mercedes 300D. 1 tank, no conversion. Replaced engine with rebuilt OM617A turbodiesel engine. Finally had good power. Engine donor for W123 coupe. (body parted out and carcass sold for scrap.)
    '85 Mercedes Benz W123 300CD Turbodiesel
    '99 Mercedes W202 C250 Turbodiesel (my darling Wife's car)[sold]
    '98 Mercedes W202 C250 Turbodiesel (my car)[sold]
    '06 Musso Sports Crew Cab well body. [Head gasket blew!]
    '04 Rexton SUV 2.9L Turbodiesel same as Musso - Our Family car.
    '06 Musso sports Crew Cab Trayback - My hack (no air cond, no heater).

    Searching the Biofuels Forum using Google
    Adding images and/or documents to your posts


  3. #3
    Join Date
    Apr 2007
    Location
    numurkah
    Posts
    579

    Re: Embarrassing lack of torque

    things to check.
    *Blocked exhaust-disconnect and drive.
    * air leak into fuel line-put a clear tube on the return line and watch for bubbles,
    *fuel line blockage,
    *valve clearances,
    *cam timing,
    *vacuum hose on the injector pump diaphragm,
    *throttle cable- does it get full throttle?
    *Do you get smoke when under full throttle up a hill? If no and you have checked everything else wind the smoke stop screw in a 1/2 turn.

  4. #4
    Join Date
    Mar 2013
    Location
    Canberra
    Posts
    285

    Re: Embarrassing lack of torque

    Thanks for the leads - I will follow up in order of least difficulty!
    Tony - no problems starting - basically instantaneous, other than single-digit winter days where I need to glow a few times before cranking. Can be a bit lumpy on these days, but goes away when the returning fuel warms up a bit. Adding 5% ULP helped here.

    I'm pretty sure it doesn't have a second filter, but likely has a screen on the IP. I will check.

    I don't know a lot about fuel starvation, but would it still be able to maintain 120km/h highway speeds on the flat if it couldn't get enough fuel? It will happily sit at 3500 rpm in 5th gear all day as long as there is no gradient. Any other obvious symptoms of fuel starvation?

    I will disconnect the vacuum hose on the IP diaphragm and see if that makes any difference - nice easy one.

    I need to get someone else to drive it so I can follow and watch the smoke levels - basically undetectable smoke when I'm driving.

    I know one thing - I'm wearing a hole in the floor pan from holding the righthand pedal flat to the floor everywhere! On any sort of hill below 2500 rpm (when turbo starts making boost), it seems to make no difference if I hold it flat or halfway….RPMs slowly climb until 2500, then rapidly until it runs out of revs at about 4000 (if the air filter is clean) or 3500 if the filter is dirty. It will happily sit there and pull at 3500 - 4000 RPM in the right gear though. My strategy on the highway is:

    1. see a hill ahead
    2. foot flat to the floor in 5th, gain as much speed as possible before the hill
    3. downshift to 4th and maintain 3500 - 4000 RPM if possible when I hit the hill
    4. watch speed wash off and revs drop to 3000
    5. grab 3rd as quick as possible to avoid dropping below 2500
    6. Repeat on down the gears as necessary until I have to stop and select low range (hasn't happened…yet )


    Thanks a gain for the tips!
    3DB
    1995 Holden (Isuzu) Rodeo 2.8TD 4X4 - B100 since April 2013
    1976 Mercedes 300D Turbo 'The Coal Grenade' - B100 since May 2016 - SOLD
    1994 Peugeot 405 SRDT 1.9L intercooled turbo diesel (Shitbox Rally car.) - B100 since August 2019 - SOLD
    @thirddegreeburns on Instagram
    @thirddegreeburns2019 on Facebook

  5. #5
    Join Date
    Dec 2007
    Location
    South Australia
    Posts
    1,243

    Re: Embarrassing lack of torque

    Quote Originally Posted by smithw View Post
    things to check.
    *Blocked exhaust-disconnect and drive.
    * air leak into fuel line-put a clear tube on the return line and watch for bubbles,
    *fuel line blockage,
    *valve clearances,
    *cam timing,
    *vacuum hose on the injector pump diaphragm,
    *throttle cable- does it get full throttle?
    *Do you get smoke when under full throttle up a hill? If no and you have checked everything else wind the smoke stop screw in a 1/2 turn.
    Click image for larger version. 

Name:	8700728195_02ae80af59_z.jpg 
Views:	206 
Size:	127.8 KB 
ID:	2173
    All good ideas except the “vacuum hose” to the IP is actually a boost pressure hose which causes the IP to deliver more fuel once the turbo delivers boost. If it is leaking or not connected then power will be down. Where the hose enters is a plate held on by 4 screws, below this is a plunger which can stick, another power loss.
    My guess is the 2 O rings on the IP pressure regulating valve (photo) have softened or rotted and are leaking fuel back to the inlet side. This reduces primary pump pressure resulting in lower injection pressure hence lower fuel delivery – less power. Replace the O rings with Viton ones and if power is not restored get a diesel shop to check the pump pressure.
    Johnnojack
    4WD Isuzu Jackaroo 3.1 200000km on WVO,(2020) 2 tank home built system 6 solenoids FPHE, heated filter fuel line and tank pickup for thicker oil. Mk. 9 version now and no changes planned as trouble free.
    Mercedes W201 190D 1986 model: 2 tank system, bigger fuel line from tank, no heat exchanger, electric pump for diesel 22000km so far

  6. #6
    Join Date
    Mar 2013
    Location
    Canberra
    Posts
    285

    Re: Embarrassing lack of torque

    Thanks, Johnno.

    If I'm going to the effort of inspecting those o-rings, I probably should just replace them irrespective in anticipation of future failure, right? Can you recommend a good place to get Viton o-rings? Are they something you can pick up at Repco?

    Also, is the valve also located below the 4-bolt cover? Looks a bit like jet from a carby...

    Thanks,

    3DB
    3DB
    1995 Holden (Isuzu) Rodeo 2.8TD 4X4 - B100 since April 2013
    1976 Mercedes 300D Turbo 'The Coal Grenade' - B100 since May 2016 - SOLD
    1994 Peugeot 405 SRDT 1.9L intercooled turbo diesel (Shitbox Rally car.) - B100 since August 2019 - SOLD
    @thirddegreeburns on Instagram
    @thirddegreeburns2019 on Facebook

  7. #7
    Join Date
    Sep 2009
    Location
    Brisbane (North Side)
    Posts
    810

    Re: Embarrassing lack of torque

    3db,

    Your description is almost an exact replica of issues I had on my 1HZ years ago. on really hot days down south at christmas I was lucky to make it off the lights at all, let alone at pedestrian speeds.

    I had a long journey chasing the problems, but I can say without a doubt the best thing I did for performance was to install a pusher pump just infront of the fuel tank selector valve. got rid of all leaks and assisted with fuel flow through filters. immediate and improved difference. I can generally keep up with who ever I want now, and dont have a need to turbo at all. Based on my own experiences, I would put money on the fact you have air leaks as an issue. Thats not to say that Johnno is also correct. The clear hose trick is very good indicator. you can move it around the system to diagnose all connections. It will behave differently under load as well, so its not always as easy to diagnose using just the hose on its own.

    Walbro make a good reliable unit, but there are plenty of cheaper facet pumps available. It also makes for changing filters an absolute breeze. Just turn the key and the empty filter primes itself. Mine is wired through the 'On' position of the ignition circuit, so if the key is 'on' the fuel line is pressurised. some will say this is not a good situation if you have a bad car crash, but its good enough for me at the moment. I should by rights look at a 'flip/flop' switch or relay so if the oil light comes on, the power to the facet pump is turned off.

    Always an opportunity to improve I guess?

    good luck with the diagnosis

  8. #8
    Join Date
    Dec 2007
    Location
    South Australia
    Posts
    1,243

    Re: Embarrassing lack of torque

    Quote Originally Posted by 3DB View Post
    Thanks, Johnno.

    If I'm going to the effort of inspecting those o-rings, I probably should just replace them irrespective in anticipation of future failure, right? Can you recommend a good place to get Viton o-rings? Are they something you can pick up at Repco?

    Also, is the valve also located below the 4-bolt cover? Looks a bit like jet from a carby...

    Thanks,

    3DB
    It's much larger than a carby jet, you will find it near or behind the throttle shaft. (not under 4 bolt cover)You will need a special tool or modified socket to remove it.
    Johnnojack
    4WD Isuzu Jackaroo 3.1 200000km on WVO,(2020) 2 tank home built system 6 solenoids FPHE, heated filter fuel line and tank pickup for thicker oil. Mk. 9 version now and no changes planned as trouble free.
    Mercedes W201 190D 1986 model: 2 tank system, bigger fuel line from tank, no heat exchanger, electric pump for diesel 22000km so far

  9. #9
    Join Date
    Mar 2013
    Location
    Canberra
    Posts
    285

    Re: Embarrassing lack of torque

    Thanks, Cade & Johnno. Will get onto it and let you know how it goes.

    3DB
    3DB
    1995 Holden (Isuzu) Rodeo 2.8TD 4X4 - B100 since April 2013
    1976 Mercedes 300D Turbo 'The Coal Grenade' - B100 since May 2016 - SOLD
    1994 Peugeot 405 SRDT 1.9L intercooled turbo diesel (Shitbox Rally car.) - B100 since August 2019 - SOLD
    @thirddegreeburns on Instagram
    @thirddegreeburns2019 on Facebook

  10. #10
    Join Date
    Jan 2008
    Location
    Sydney
    Posts
    833

    Re: Embarrassing lack of torque

    Your Fuel consumption sounds wrong for that size engine - i have a 6.5L in a 3.5T car and do not get much worse than that - this may just be a symptom of the problems but go with what the other boys have suggested first.

    I would definitely +1 on the pusher pump

    Craig
    Last edited by craigcurtin; 2nd February 2015 at 08:30 AM.
    Holden Suburban K2500 1998 6.5L Turbo GM engine
    210,000KMs (90,000 on new crate motor)

    Currently 2 tanks in and working - 90 litre BIO tank and main tank of 160L WVO

    30 plate FPHE in Engine bay and Helton Dual coil in rear
    Walbro FRB-5 pusher pumps x 2

    50,000KM on Veg and 10,000Km on B100

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •