| Author | Message | ||
     Will Cupp (W_cupp) Senior Member Username: W_cupp Post Number: 404 Registered: 07-2003 |
Disco with the 4.0L... Runs fine, drives fine, no raw gas smell from exhaust, shifts fine, new fuel filter, new plugs and wires, no check engine light, no stored codes... Only getting about 125 miles to a TANK of gas (92-93 oct) What could be wrong with this guys truck? | ||
| Will Cupp (W_cupp) Senior Member Username: W_cupp Post Number: 405 Registered: 07-2003 |
And no noticeable gas leaks... | ||
| Tom Fioretti (Tom_in_md) Member Username: Tom_in_md Post Number: 158 Registered: 02-2003 |
Maybe dumb question: Is he sure it's filling up completely when he re-fuels ? How many gallons are going in ? 125 miles per tank is insane. | ||
| Chris Browne (Chris_browne) Senior Member Username: Chris_browne Post Number: 700 Registered: 02-2003 |
125 miles would be good if he was in low range. How many miles? Any damage to cats? | ||
| Will Cupp (W_cupp) Senior Member Username: W_cupp Post Number: 406 Registered: 07-2003 |
Nothing noticable on the outside of the cats, but not sure in the inside. It seems if they were cloged the power would be slugish?? The truck has a little over 100,000 miles. | ||
| zane pukajlo (Zane) New Member Username: Zane Post Number: 39 Registered: 03-2003 |
Have you tried swapping in some new O2 sensors just to see if that is the problem? | ||
| Shaun Power (Shaunp) Senior Member Username: Shaunp Post Number: 266 Registered: 05-2003 |
It must be rich as to use that much fuel, I'd check the lambdas and the temp sensor. | ||
| Will Cupp (W_cupp) Senior Member Username: W_cupp Post Number: 407 Registered: 07-2003 |
have not tryed O2 sensors, but would that throw a code if they were bad? What is the lambdas and temp sensor? Is that like a bumper belt or muffler bearing? | ||
| Jeff Mclaird (Granitedisco) Senior Member Username: Granitedisco Post Number: 288 Registered: 08-2003 |
Yep - I'd be looking at the O2 sensors. I just did nearly 280 miles on $20 of gas (fuel low light came on coming into the driveway) - just over 10 1/2 gallons in NH. regards Jeff | ||
| Jack Leitch (Liveattheedge) Member Username: Liveattheedge Post Number: 230 Registered: 12-2003 |
Wow, i'm lucky to get 10mpg. I checked my engine oil today and it smelled faintly of gas. Could i be loosing fuel somewhere in the engine? Cheers Jack | ||
| Jack Leitch (Liveattheedge) Member Username: Liveattheedge Post Number: 231 Registered: 12-2003 |
seems to be running rich also, i always clean the exhaust pipe when i wash it, (about a month ago was the last time), and now it has a quarter inch of black buildup on the outside of the pipe. Anyone know how to adjust the fuel mixture, without loosing power, i need that more than mpg. Cheers Jack | ||
| Shaun Power (Shaunp) Senior Member Username: Shaunp Post Number: 269 Registered: 05-2003 |
Lambda sensors = O2 sensors, Engine temp sensor will make them run rich if faulty as well, and doesn't often give fault code, the ECU just thinks the engine is cold and runs cold start fuel map ie rich. | ||
| Will Cupp (W_cupp) Senior Member Username: W_cupp Post Number: 409 Registered: 07-2003 |
Where would the engine temp sensor be located? Is it the same one that runs the gauge inside the truck? | ||
| Billy Deakins (Discodog) New Member Username: Discodog Post Number: 38 Registered: 11-2003 |
Damn Jeff, I'm lucky to get 280 out of $50 of gas! You better hold on to that Rover! | ||
| Toddrover (Toddrover) Member Username: Toddrover Post Number: 127 Registered: 04-2003 |
Jeff - How is it possible to be getting upwards of 28 mpg on this engine ??!!?? I'm pretty close to what Bill is getting and Front O2 sensors are fairly new ...if I was getting 18 or 19 mpg I'd be thrilled... | ||
| Chris Browne (Chris_browne) Senior Member Username: Chris_browne Post Number: 707 Registered: 02-2003 |
The computer uses the oxygen sensor’s input to regulate the fuel mixture, which is referred to as the fuel "feedback control loop." The computer takes its cues from the O2 sensor and responds by changing the fuel mixture. This produces a corresponding change in the O2 sensor reading. This is referred to as "closed loop" operation because the computer is using the O2 sensor’s input to regulate the fuel mixture. The result is a constant flip-flop back and forth from rich to lean which allows the catalytic converter to operate at peak efficiency while keeping the average overall fuel mixture in proper balance to minimize emissions. It’s a complicated setup but it works. When no signal is received from the O2 sensor, as is the case when a cold engine is first started (or the 02 sensor fails), the computer orders a fixed (unchanging) rich fuel mixture. This is referred to as "open loop" operation because no input is used from the O2 sensor to regulate the fuel mixture. If the engine fails to go into closed loop when the O2 sensor reaches operating temperature, or drops out of closed loop because the O2 sensor’s signal is lost, the engine will run too rich causing an increase in fuel consumption and emissions. A bad coolant sensor can also prevent the system from going into closed loop because the computer also considers engine coolant temperature when deciding whether or not to go into closed loop. | ||
| Edward Cho (Echo63) New Member Username: Echo63 Post Number: 7 Registered: 02-2004 |
This thread is very interesting. Being new to this board (and new to Land Rover Discovery), I was a bit surprised at my 2001 Disco II's poor gas mileage. I live in SF bayarea where 91 Octane premiums cost anywhere from $2.35 to $3.00 per gallon, and a full tank of little over 20 gallons would only last about 250 miles on combined driving. I only recently got this car, and have not had a chance to drive long distance to check for freeway mpg. If I can bump this up to 18 to 19 miles to a gallon I would also be thrilled. My question is, how do we check whether or not the O2 sensor is working properly? I just got my car smogged, and it passed with flying colors. Wouldn't a faulty O2 sensor fail me in smog tests? Also, my temp guage is at a midpoint while I'm driving - wouldn't a bad temperature sensor overheat the car? Do I have to take my car into a shop to determine the proper functionality of these sensors? Thank you all for guiding this newbie to the intricacies of a Disco. | ||
| Jim Macklow (Macklow) New Member Username: Macklow Post Number: 40 Registered: 03-2003 |
My mpg went from 12 to 15 when I started driving conservatively... no more than 2000 rpm when accelerating and no more than 65/70 mph on the freeway. My mpg jumped from 15 to 17 when my power steering pump seized and I replaced with a rebuilt. It's been very hard psychologically to keep the revs below 2000, especially when all the type-A's are tailgating me on the onramp (since I am a semi-reformed aggressive type-A (asshole) driver). The only time I go above 65 on the freeway is when I'm on long (1000+ mile) trips, where difference between 65 and 85/90 means arriving hours and hours earlier. For short trips, I take it easy, and notice that the same people are tailgating and waving their arms whether they're stuck behind me or that other guy going faster (but not fast enough, it seems). Note: Acceleration is slow at 2000 rpm... but as posted in another thread, going full throttle doesn't seem to speed things up significantly. | ||
| Geoff 93 RRC (Geoff) Senior Member Username: Geoff Post Number: 313 Registered: 11-2002 |
It would be interesting to go to an emissions testing center and get the CO level read. This would really give a good idea how well the mixture is trimmed. | ||
| Jack Leitch (Liveattheedge) Member Username: Liveattheedge Post Number: 244 Registered: 12-2003 |
Can't be that bad, i may get shitty gas mileage but it passed the California Emmissions test with flying colors. | ||
| eduardo (Jmonsrvr) Member Username: Jmonsrvr Post Number: 86 Registered: 07-2003 |
interesting thread....i too have the 1/4 inch rim of soot at the end of my new nrp exhaust....well about 6 months old now.. o2 sensors are from nathan are around a year old now...could it be the aftermarket sensors? will this heavy build up eventually rot out my new cats? i always change oil religously, same with plugs, i run 8mm magnecor wires...cant figure out why there is that contstant ring.... | ||
| Melissa (Roverchic) Member Username: Roverchic Post Number: 191 Registered: 02-2004 |
This could be a stupid ?? But I had no idea that power steering effects MPG ?? I have a very minor leak----but holds fluid. Melissa | ||
| Reed Cotton (Reedcotton) Senior Member Username: Reedcotton Post Number: 336 Registered: 01-2003 |
Is your speedometer/ odometer accurate? This could make your milage look good or bad with everything else working fine. Different tire sizes can have the same effect. It might be worth having it checked. -Reed | ||
| David (98disco) New Member Username: 98disco Post Number: 4 Registered: 03-2004 |
Melissa - Don't worry the leak you described shouldn't be a problem. Actually fairly common for the Rovers. If your power steering pump was seizing up (bad bearings) the pulley would be hard to turn ... and since the PS pulley is powered by the engine crankshaft there would be an effect on the engine performance. Basically it would be dragging down the engine a little bit. It's like the difference between jogging a mile vs. jogging a mile with a 50 lb. pack on your back. Anyway, in the case of the power steering the situation won't normally last long because something's gotta give (break) - usually the drive belt if the bearings seize. Just keep your eye on the fluid level and you'll be ok. PS - check your PS fittings. They may need to be tightened. | ||
| David (98disco) New Member Username: 98disco Post Number: 5 Registered: 03-2004 |
Will - Is this Disco stock in configuration, or does it have some mods? Larger tires or lower gears can make quite a difference - especially if the gears have been changed to the 4.7's. What tire pressure is being run? Big tires at 20 psi will make a difference too. You usually get codes stored if you have bad O2 sensors, so it's probably not that - but could possibly be (see Chris Browne's message above). As Chris said it could be the coolant temp sensor and that would be my guess before the O2 sensors. Also, you said the spark plugs were changed - have you checked for proper gap? One other thing could be valves not seating properly - but this should throw a code. Even a dirty air filter has some effect on gas mileage. Could be a combination of a lot of small things plus driving habits. There's not a RV in tow is there?  | ||
| Brian O'Connor (Hooky) Member Username: Hooky Post Number: 92 Registered: 09-2003 |
I will team up with Jim’s story above, easy on the accelerator can make a significant difference with MPG around town, especially at highway speed, keep it steady – use cruise when possible – trying to maintain a steady pace by foot isn’t as smooth. Also keeping at or below 65 will get you the best mileage, your tach should read under 2500 rpm. I used to watch the tach like a hawk not the speedo, there was a time when I was broke beyond belief due to a failed marriage, the Disco was new, and I was upside-down in it and it was better for me to gut it out and keep it. I was a penny-pinching fool then – only the cheapest gas would do, and I checked my tire pressure weekly. If Mileage is your number one concern add 5 psi to what your supposed to have in your tires. I got 85,000 miles out of those BFGs and the tire guy was wondering why I was replacing them – so the slight addition will not cause premature wear, but it will help squeeze an extra mpg out. BTW have you checked your air filter lately? | ||
| Melissa (Roverchic) Member Username: Roverchic Post Number: 192 Registered: 02-2004 |
David: Very interesting about the power steering pump. The only time that I have a problem with the steering is when I first start the car in the morning. Hard to turn---really tight. But loosens up once the rover is driven for about 5 minutes(once she is warmed up). Humh.. Will exam the pump again tonight. The factory crimp style clamps are what appears to be leaking. Thanks! Melissa | ||
| David (98disco) New Member Username: 98disco Post Number: 7 Registered: 03-2004 |
Melissa - There's not much you can do about the crimped-on hose fittings outside of buying new hoses (still a common leak). I was referring to the threaded fittings that screw into the steering gear box. I've had those get so loose you could turn them with your fingers. Yes, the steering will normally get easier after the engine is run and the PS fluid warms up a bit - especially if you live in a colder climate. It all sounds good/normal to me. Good luck. PS - don't overfill the PS reservoir that's hard on the pump. | ||
| Melissa (Roverchic) Member Username: Roverchic Post Number: 193 Registered: 02-2004 |
David: Thanks! It was overfilled (could be part of the reason why it was leaking to begin with). I removed some of the fluid with a straw and will see how we go from there. Best,Melissa | ||
| David (98disco) New Member Username: 98disco Post Number: 8 Registered: 03-2004 |
Melissa - That certainly can make it leak. PS is a hydraulic system that heats up and expands, so over filling is a no-no. It's possible the extra fluid was making it harder to steer too. Careful with the straw, and no cigarettes - that fluid is flammable. But, it doesn't taste as bad as battery acid feels in the eye! ouch! |
