B
Bigcat6969
Guest
1996 D1 with 187,000 miles:
I have found the source of my intermittent miss-fire / piss-poor performance (especially when in the wet) and wanted to post what I believe to be the root cause.
First some history:
For the past year or so my D1 would run poorly at times, especially after splashing through water, as though it was 'hunting' for a spark, fuel etc. This would be accompanied by rough idle but was really noticeable at highway speeds (50-65) - just really down on power especially up hills. I lived with it for a while and suspected some sensor going bad (especially if wet) or perhaps even the ecu itself (4.0 GEMS system).
Trying to find a solution:
In any event after checking all the obvious stuff (vacuum leaks, battery connections, fuel pressure, grounds, O2 sensors, IAC valve, TPS etc) I happened upon a few threads here for similar problems and all mentioned CRANKSHAFT POSITION SENSOR. I read up a little on this and RAVE calls this 'THE MOST IMPORTANT SENSOR ON THE VEHICLE', yet then goes on to say that there is no 'limp home' mode if this sensor goes bad - vehicle will just quit running. However, the threads I read here mentioned cracked / worn wiring going into the sensor itself via the plug connector.
Homing in on the root cause:
My DI had never actually quit though and always started first time and generally ran well unless very wet outside (unavoidable puddles etc). So I was still a little sceptical of the Crankshaft sensor thing but decided to take a look anyhow.
Removing and inspecting the sensor:
The Crankshaft sensor is located on the lower right of the engine when viewed from the front just above where the Y pipe connects to the exhaust manifold on that side. It is tricky to reach but not impossible and can be removed without dropping the exhaust. It is held in place by two 7mm cap screws that also attach a heat / protective shield around it. Once the screws are loose it pops out easily and will then dangle free hanging on by the wiring harness section that drops down from just under the coil pack on top of the rear of the engine. By pulling out the cap screws the shield can be removed and the sensor unplugged from the wiring harness. The wiring harness can then be pulled up from the top of the engine for easy inspection.
Condition of the sensor:
The sensor plug connector and shield were covered in oily mud and sludge from years of accumulation. I cleaned the sensor & its plug connector, and the shield, with carb and electrical cleaner. All looked in decent condition.
Condition of the wiring harness and its plug:
This was a different story. As soon as I looked at the wires running into the connector I could see the problem as plain as day. BOTH WIRES were devoid of any insulation for about one inch before they sent into the connector. One is meant to have green insulation and the other brown - these had neither, it had all flaked / broken off exposing bear copper. See the PICTURE ATTACHED of the connector and where the wires run in from the harness.
The fix:
The connector and its wiring were in such poor condition the whole thing needed to be replaced. I spliced in a new connector and refitted the sensor and its shield. I placed some heat reflective tape around the shield as it would seem that heat from the exhaust had been the culprit in causing the sensor wire insulation to crack and flake off in the first place.
The result:
I can now play in the water and mud again to my heart's content. Drove through some deep puddles at speed and slowly and absolutely no problems at all.
Conclusion:
If your Disco is showing any signs of poor performance, rough idle, or just wont start and the cause is not related to anything obvious and it is starting to drive you bonkers, then crawl underneath and check the condition of that CRANKSHAFT SENSOR and its associated WIRING - it might just be the cause as it was in my case.
Best of luck,
Rob.
I have found the source of my intermittent miss-fire / piss-poor performance (especially when in the wet) and wanted to post what I believe to be the root cause.
First some history:
For the past year or so my D1 would run poorly at times, especially after splashing through water, as though it was 'hunting' for a spark, fuel etc. This would be accompanied by rough idle but was really noticeable at highway speeds (50-65) - just really down on power especially up hills. I lived with it for a while and suspected some sensor going bad (especially if wet) or perhaps even the ecu itself (4.0 GEMS system).
Trying to find a solution:
In any event after checking all the obvious stuff (vacuum leaks, battery connections, fuel pressure, grounds, O2 sensors, IAC valve, TPS etc) I happened upon a few threads here for similar problems and all mentioned CRANKSHAFT POSITION SENSOR. I read up a little on this and RAVE calls this 'THE MOST IMPORTANT SENSOR ON THE VEHICLE', yet then goes on to say that there is no 'limp home' mode if this sensor goes bad - vehicle will just quit running. However, the threads I read here mentioned cracked / worn wiring going into the sensor itself via the plug connector.
Homing in on the root cause:
My DI had never actually quit though and always started first time and generally ran well unless very wet outside (unavoidable puddles etc). So I was still a little sceptical of the Crankshaft sensor thing but decided to take a look anyhow.
Removing and inspecting the sensor:
The Crankshaft sensor is located on the lower right of the engine when viewed from the front just above where the Y pipe connects to the exhaust manifold on that side. It is tricky to reach but not impossible and can be removed without dropping the exhaust. It is held in place by two 7mm cap screws that also attach a heat / protective shield around it. Once the screws are loose it pops out easily and will then dangle free hanging on by the wiring harness section that drops down from just under the coil pack on top of the rear of the engine. By pulling out the cap screws the shield can be removed and the sensor unplugged from the wiring harness. The wiring harness can then be pulled up from the top of the engine for easy inspection.
Condition of the sensor:
The sensor plug connector and shield were covered in oily mud and sludge from years of accumulation. I cleaned the sensor & its plug connector, and the shield, with carb and electrical cleaner. All looked in decent condition.
Condition of the wiring harness and its plug:
This was a different story. As soon as I looked at the wires running into the connector I could see the problem as plain as day. BOTH WIRES were devoid of any insulation for about one inch before they sent into the connector. One is meant to have green insulation and the other brown - these had neither, it had all flaked / broken off exposing bear copper. See the PICTURE ATTACHED of the connector and where the wires run in from the harness.
The fix:
The connector and its wiring were in such poor condition the whole thing needed to be replaced. I spliced in a new connector and refitted the sensor and its shield. I placed some heat reflective tape around the shield as it would seem that heat from the exhaust had been the culprit in causing the sensor wire insulation to crack and flake off in the first place.
The result:
I can now play in the water and mud again to my heart's content. Drove through some deep puddles at speed and slowly and absolutely no problems at all.
Conclusion:
If your Disco is showing any signs of poor performance, rough idle, or just wont start and the cause is not related to anything obvious and it is starting to drive you bonkers, then crawl underneath and check the condition of that CRANKSHAFT SENSOR and its associated WIRING - it might just be the cause as it was in my case.
Best of luck,
Rob.
