rrdiver
New Member
- Posts
- 55
- Location
- North Wales
Like a lot of others, (including Land Rover dealers) I have changed fuel pump, O-rings, temperature sensors, return lines etc. Also taken on board that others have changed injection pump, No.4 injector, etc. etc. My problem of being lumpy when stopping at a halt sign with a hot engine, but clearing with a slight blip on the accelerator has been a nightmare to solve. It was caused by additional current draw from items such as brake lights causing a volt drop on the sequential injection system because of high resistance relay contacts (heat damage) with subsequent malfunction. Only happens when the contacts have heated up after time and disappears when cold. Blipping the throttle increases the voltage from the alternator and temporarily clears the fault.
Engine fuse box - Siemens Relays RL6, (Aux Relay 1,) RL12 (Fuel Pump), RL19 (Engine Main Control) and RL15 (Sequential Multi-Port Injection + BECM) were all found to be maginally faulty when hot. I believe RL15 was the main problem, but replaced all five for safety. RL15 (Green) is part no. YWB10031. The other 3 are YWB10012L.
Checking diagnostics using a Rovacom Lite confirms that after replacing the relays (I initially swapped their positions with others in the fuse-box) there are slight differences in most of the readings, compared to sets taken prior to changing relays, both without and with the fault present. Fuelling is slightly up from previous hot no-fault condition at around 5.5 mg/str., as is tick-over speed. Probably means slightly less enconomy, but I had been wondering why mine was so good on fuel. Previous logs of the fault condition had shown fuel quantity dropping to 0.25 mg/str. with erratic high tick-over speed.
There are other possible reasons for a lumpy tick-over, but this is a lot cheaper than replacing the other items. If the symptoms are the same as mine were, with this strange effect of blipping the throttle after stopping, this could well be the reason and I would suggest changing these relays first. My mileage is now around 98,000 but it has had this problem for approximately the last 8,000 miles.
Engine fuse box - Siemens Relays RL6, (Aux Relay 1,) RL12 (Fuel Pump), RL19 (Engine Main Control) and RL15 (Sequential Multi-Port Injection + BECM) were all found to be maginally faulty when hot. I believe RL15 was the main problem, but replaced all five for safety. RL15 (Green) is part no. YWB10031. The other 3 are YWB10012L.
Checking diagnostics using a Rovacom Lite confirms that after replacing the relays (I initially swapped their positions with others in the fuse-box) there are slight differences in most of the readings, compared to sets taken prior to changing relays, both without and with the fault present. Fuelling is slightly up from previous hot no-fault condition at around 5.5 mg/str., as is tick-over speed. Probably means slightly less enconomy, but I had been wondering why mine was so good on fuel. Previous logs of the fault condition had shown fuel quantity dropping to 0.25 mg/str. with erratic high tick-over speed.
There are other possible reasons for a lumpy tick-over, but this is a lot cheaper than replacing the other items. If the symptoms are the same as mine were, with this strange effect of blipping the throttle after stopping, this could well be the reason and I would suggest changing these relays first. My mileage is now around 98,000 but it has had this problem for approximately the last 8,000 miles.
