I have a 2003 Disco with 157k. It will start and idle, but if I give it any gas it acts like it is starving for fuel. I can rev it up normally if I give it starting fluid. It acted similarly when the MAF went out, and needed to be replaced, but it ran great if I unplugged the MAF(was replaced about 4 years ago). Now if I unplug the MAF, it just dies, and is difficult to get to restart. I thought fuel pump, so I replaced it. No improvement whatsoever. I thought fuel pump relay, so it pulled it, and tested it, it clicks, and was getting 11.8v through it with my multimeter when closed with a battery measuring 12.7v. Relay should be functioning I think? The CPS was replaced by a dealership about a year ago when my Mom was borrowing it for the summer. Also all four o2 sensors (OEM Bosch is what I bought) were replaced last year, and I probably haven't driven it 300 miles since then.

Codes in order:
P1884
P0102 (figured it threw that when I unplugged the MAF while it was running)
P0300
P0301
P0308
P0303
P0302
P0175
P0172
P1230
P0463
P0304
P0306

 

I would start by checking the fuel pressure just to be 100% certain its ok, even though you would think it ought to be with the work you've done. There's a fitting on the fuel rail you can easily use for testing. If it's low check the voltage at the fuel pump connector and see if it's getting a full 12v or not. I would clear those codes and see which ones reset. p1230 is for the fuel pump relay circuit but may have just been caused by unplugging it during your testing.

 

Previously I tested the pump, and it was getting 12v. I tested it yesterday, and was getting like .4v, which didn't make sense. I don't think that is enough to even supply fuel at an idle. Maybe I wasn't using my mulitimeter correctly? I tested the black wire with the black lead, and the other one I thought was power to the pump ( I think it was white w/ a purple stripe... the other large wire) with the red lead and got .4v. One of the other wires was green and black I think, and it tested at 5v, I think that one is for the fuel gauge.

 

Harbor Freight sells a fuel pressure gauge set for about 20 bucks, or you may be able to borrow one from an autoparts store with a loaner tool program. Honestly I would start there and see what you have, if it's low then we can go from there. Definitely an odd situation but knowledge is power when diagnosing a problem and it would be great to know just what kind of fuel pressure you've got so you can proceed accordingly. If fuel pressure is normal then no need to check any further into the fuel pump voltage etc. If not then yes we will need to test/diagnose the cause of low voltage at the pump.

 

The set I looked at for $20 said excludes Bosch. I almost bought it anyway thinking it would fit. It should fit then?

 

Hooked up a fuel pressure gauge to the rover today, and when the pump kicked on to prime it charged to 46 psi. When I started it, it ran from 56-60 psi. It seems like my pump is running correctly.

 

I would investigate the coil pack... I doubt that plugs or wires would cause you to throw that many misfire codes at one time...

Another thing to check is the crank sensor or crank sensor wiring... If insulation on a crank sensor wire is burned through and is hanging near enough to touch when the engine moves under throttle... it can ground out. Also make sure your plug wires are routed away from the crank sensor wires. Voltage leak can cancel the signal in wiring. New to Rovers... but I've seen both happen in other motors.

Wish you luck,

Clay

 

Probably will need a scan tool at this point so you can monitor MAF readings etc. And clear the codes to see which reset. Could always be something obscure like clogged injectors too I suppose although that seems unlikely. Did the problem start out of the blue one day? What's the back story on it, you mentioned it had sat around a lot since last year. I've seen rodent damage to wiring harnesses on cars that sit too.

 

Ok. Forgot to mention it before, but I was out tinkering on it today and remembered that if I quickly and repeatedly pump the gas pedal, it will rev up eventually all the way to 4500 or so, and if I keep pumping it, it seems like it would hold there. Probably doesn't help at all, but I thought I'd mention it. Scanner should be here on Mon

 

Guess 1. That your MAF is bad ... Had the exact same symptoms... It will start if you pump the gas... you can keep it running if you keep pumping... you might find a happy medium... at one point it was running without pumping the pedal...

Guess 2. Break in the plastic vacuum tube from the brake servo... (booster).. If it runs better when it revs... check the ends... a vacuum can seal itself under load. It will run like crap at idle if it can't seal itself... give it the beans and it sucks itself together.... closing the leak...

Good luck,

Clay