I have a new to me 1997 Disco 1 that did this on my way to work this morning. This weekend I had removed the front driveshaft to do replacement u joints and last nights test drive was uneventful. I let the car warm up this morning and drove it about a 1/4 mile when the revs dropped out and it wouldn't go above 1100 rpm. I could get a little bit of throttle response if I pumped the gas but not much. I was able to limp it home. It would rev in neutral or park, but with hesitation. IE, I would open throttle and it would be a split second before it would rev up. It would also idle and not die - it was just out of power. There was no loud noises or such when it cut power - it just dipped and never came back. The weather in my area has been cold the last few days and it snowed on Saturday.

Things I have replaced since purchasing the vehicle (that aren't u-joints lol):
plugs, wires, 1 upstream o2 sensor on the driver side.
Things I'm (mostly) sure previous owner replaced:
injectors
Codes:
0307 (misfire on 7 - I am thinking it might be coil related? I have some new coils on the way) Possibly head gasket? But plug is not steam cleaned. No indicators of head gasket in oil or coolant. prior to o2, plugs and wires replacement I had codes on 1, 3, and 7. 1 and 3 went away after the plug change.
1316 and 0300. There was one also for bad cat which I assume could also be bad trail o2 sensor. I was planning on a new y pipe soon anyways as I had to jb-weld the new upstream o2 sensor I just replaced as the bung was wallowed out. The passenger side cat looks to have been replaced at some point but the driver side is the round style and no indicators that its been replaced.

Reading on the forums it looks like it could be a few things. I was hoping for wisdom as to more/most likely culprit(s).
1. TSS sensor. I do have speedometer as far as I can tell tho - it was reading 10mph as I limped it back.
2. Cam or Crankshaft position sensor. I thought tho if these go bad the car wouldn't run at all.
3. Bad gas or ice/water in gas? This is what it felt like - lots of popping and stumbling on the limp home. But the times Ive had bad gas i usually cant keep the car running.
4. Head gasket. But again no clear indicators of bad gasket either from plug or fluids or exterior of engine. I haven't pulled the plugs to see after this latest incident.
5. plugged cat? could it happen that quickly or would there be a gradual buildup of poor performance?
6. timing chain/cam issue. I am not sure if this is a possibility but I would also think this would prevent engine from running.

I appreciate you all taking the time to read all that. Thanks for the input!

 

I would probably start with an IACV. Not too expensive and easy to replace.


https://landroverforums.com/forum/di...pensive-81775/

Get an OBD dongle and app to help understand what the engine ECU is seeing, and what may be whacky or missing.

 

Thanks! I have a cheapy that just reads codes. I'll have to get a better one soon.

Update to earlier: upon arriving home I tried starting the rig. It would not start.

 

I would have said VSS but VSS is just drop of power vs stumbling/popping.
Could be ice+vss but still.
Watch your VSS via ODB and see if it reads way too fast and then dives

 

You're losing fuel pressure. Replace the fuel sending unit. In the cargo area, under the carpet, remove the access panel and then open the fuel tank. Pull out the old sending unit, and insert a new one. It is possible to replace just the motor, but replacing the hoses can be tricky if you don't have the clamps and tool. They're ear clamps if I recall.

 

Fuel pressure is easy to measure, there is a port on the fuel rail where a gauge can be connected (just like my '96). Of all the replies above, low fuel pressure makes the most sense. Could simply be a clogged fuel filter. My truck runs 20 psi (key on, engine off), 33 psi (engine on), 40 psi (engine on, vacuum tube removed from fuel pressure regulator). Maybe borrow a gauge from a parts store, and be extra careful about gas spills or sprays.

These are not symptoms of a bad IACV. The IACV controls engine speed at idle only. If it idles fine, it is not the IACV.

 

Nice - I already have a fuel filter on hand. I'll pick up a fuel gauge and check the pressure.

 

Just a small update as I haven't had a chance to wrench on it yet. It had some issues starting this morning but it would fire off immediately, run fine for 30 seconds then sputter out. I got it idling and once it warmed up there was the big and sputter again. Seems like that is definitely fuel related. Or a sensor somewhere in the engine compartment that doesn't like being warm.

 

Will it hold idle if you flutter the pedal or does it die regardless?

 

I like the fuel delivery angle. Try to get a fuel pressure gauge. I grabbed one from Harbor Freight some time back, this one IIRC. Works good enough. A lot easier to check pressure at the fuel rail than yanking the fuel pump/sender unit. Not saying that is hard, kinda easy actually. Unless all the phillip head screws are rusty.