I have a 2003 Disco 4.6 with 95k with SAI. I have read every post concerning SAI, and codes that there are to read but I have a problem that I hope I can get some help on that eludes those prior posts. For months the SAI pump has become louder and louder. Having owned five other LR (Discos and RR) and have never had a SAI model so this noise was foreign and since I had issue with my blower on the HVAC a couple of years ago, I chalked it up to preparing to replace the blower. But, after much reading here and other sources, I now know I have a blockage in my SAI system or at least something wrong within. I removed cleaned and replaced both SAI solenoid valves and the Idle Air Control just for good measure. I even ran the engine with the pipes removed from the valves. The passenger side had a slight vacuum and the drivers side seemed to have a positive flow, if only slightly.

with the vacuum lines attached to the control valves, the engine idles with a definate whum, whum, whum, whum and with those control lines off the sound disappears and purrs like it should. So I did an induction cleaning with SeaFoam, which was quite exciting, just as promised, cleared the codes with my reader and took it for a drive. The 14XX codes went away but the 0302 cylinder misfire kept showing back up when the throttle position open more than about 50% load. If I drove like I had an egg under my foot, I could easily reach highway speeds with no SEL, but if I initiated the throttle more than 50% or any variation of quick accelerating, the SEL flashes and codes out to always 0302 but often another random cylinder will show up.

So, having educated myself of the SAI, I am convinced that I need at least one control solenoid and a control valve, but my question is why the constant misfire on that number two and the other randoms while under a load? The second question would be about the "whum, whum, whum" with the vacuum lines connected but I think they will be solved by the new valve and solenoid.

Recent Maintainence:
Oil change 3,000 miles ago Mobil 1
Replaced both coil packs, plugs and wires 15,000 miles ago 7mm (I know 8mm would have been better)
SeaFoam induction cleaning (after the issues started)
Throttle body cleaning (after the issues started)
Replace air cleaner with new paper filter (after the issues started)
Cleaned and replaced SAI pump, solenoids, and IAC

I was getting 1412, 1415 and 0302 consistently prior to any work with the SEL going from off to flashing when the troubles began.

Thanks for everything and I promised once it is sorted, I will post the solution whether it come by info here or my mechanic. Thanks in advance. DnD

 

Did you replace the SAI pump filter?
What brand plug wires did you use?
What spark plugs?

 

The pump filter was actually very clean, but I did blow it out. Not sure of the brand of spark plug wires and the spark plugs were direct replacement OEM Champion. I pulled the number 2 spark plug to look at it following the misfires and it looked no different than the number 4 or 6. Thanks for the reply, DnD