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ashr
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32 Posts
Discussion Starter · #1 ·
So, I refurbished some of the top end about 40k miles ago, New Head Gasket and a bunch of other items in there. About 5k miles ago I started having 3 symptoms show up approximately at the same time. Could be coincidence but thought I'd list then just for background :
1) The ODBi port intermittently doesn't power up (checked pins no voltages when this is happening) as well the dome light is not working most of the time and we have intermittent XYZ switch limp home mode kicking in . These are all on the same harness from te BCU so I think they are a related single problem
2) Low Oil Pressure comes up when engine is warm. But only when RPMs are below 7. (Mechanic hypothesized a spun can bearing. there are currently no leaks anywhere)
3) consistently getting engine hesitation under load and only under load after the engine is hot. I am sure it's not the plugs or wires, they seem fine and as I say it only happens under load. I reset the ODBi and I will get a P0300 and P0304 after it happens but not until (if I drove under 2000rpm for days there would be no stutter and no misfire codes).


I think it's a vacuum leak ! But I can't find it. Any suggestions? Could it be SAI related or MAF related?

disco ii 2004 165k
 

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'03 Disco SE
Joined
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573 Posts
1. The OBD port issue could be a bad fuse. Check [URL=http://www.landroversonly.com/forums/usertag.php?do=list&action=hash&hash=2]#2 0[/URL] in the interior fuse box and #2 on the engine fuse box. Replace even if they "look" good as a precaution. Otherwise it's probably a ground or short somewhere and you'll need to get a multimeter to start checking wires.

2. Resolve the oil pressure issue IMMEDIATELY. The warning light comes on at 7 PSI which is far too low - you're already doing damage to the bearings at that point. Very infrequently the light is caused by a faulty pressure sender, so you can replace it as a matter of course (costs $10) - but I doubt that this is the issue. Get your mechanic to hook up an oil pressure gauge (there is a port right above the oil pressure sender) to check actual numbers. You should be seeing at least 12+ psi at warm idle.

It's very likely that your oil pump gears are cracked. It's a VERY common issue and requires you to remove the timing cover to replace the pump gears inside. Not a difficult job but a little involved. Only special tool you need is a fan clutch tool to remove the cooling fan. You can get a kit to replace the gears (includes gears, gaskets, oil seal) for $120.

3. The SAI system will not cause misfire codes. Neither will the MAF. If it were a vacuum leak it would cause a rough idle that goes away under load, so it won't be that.

I'm not exactly sure how your can tell that your plugs/wires "seem fine" just by looking at them. Missing under load is a typical plug/wire issue. When was the last time they were replaced? These engines are hard on plugs and they should be replaced every 30K miles or so - even with platinum. What about the wires? If they're still the gray factory ones they NEED to be replaced - they're seriously under engineered for the application and fail often. You can get very high quality STI wires on ebay for $35.
 

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ashr
Joined
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32 Posts
Discussion Starter · #3 ·
@BosnianDiscovery - Boy what an Idiot I have been. I was in total denial about the pluggers. Probably because it's a bear of a job to replace them. But I did (and new plugs), and the hesitation and misfire went away completely! Acceleration and power have returned like new.

Also, I dug open the passenger foot well and looked at all the wire harnesses from the BCU, with a little bit of re positioning all the BCU issues seem to have disappeared. Probably will need to replace the harness down there.

So, now I just need to install an aftermarket Oil Pressure gauge and consider rebuilding the oil pump. Thanks for the advice.
 
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