Rover 3.9i Running Rich troubleshooting

**FisherX** · 30th January 2017, 12:04 PM

Wooh, no need to go crazy,

Just start with a filter and oil change of the gearbox if its condition is unknown. I might sort it out, it has for me in the past.

I use the Nulon multi vehicle synthetic ATF. It's a bit expensive but it works for me and goes in anything. But a decent DexIII will be just fine and a heap cheaper.

Also check the kick down cable is set correctly.

Filter Kit to service Land Rover Defender/Discovery/Range Rover auto gearbox

**101RRS** · 30th January 2017, 04:30 PM

Originally Posted by bee utey

No oxygen sensors on a 3.9 in Australia.

Oh ok - just that a friends 101 has a 3.9 running a 4CUIX and it has O2 sensors - obviously not original.

Maybe if the D1 had O2 sensors it would not be running rich then

garry

**drover81** · 30th January 2017, 06:01 PM

Originally Posted by FisherX

Wooh, no need to go crazy,

Just start with a filter and oil change of the gearbox if its condition is unknown. I might sort it out, it has for me in the past.

I use the Nulon multi vehicle synthetic ATF. It's a bit expensive but it works for me and goes in anything. But a decent DexIII will be just fine and a heap cheaper.

Also check the kick down cable is set correctly.

Filter Kit to service Land Rover Defender/Discovery/Range Rover auto gearbox

Phew! I thought the Amazon kit was a bit over the top!

I plan on doing the filter soon - just need to find the time and a willing offsider. Have the filter and penrite Dex III waiting for me in the garage.

Kickdown seems to work fine judging by the response compared to the light/medium/heavy throttle vs load as detailed in the workshop manual.

**drover81** · 1st February 2017, 03:04 PM

Originally Posted by drover81

Thanks guys - hope all had a good Aus day.

Since the last post I've got rovergauge working (finally - lesson learnt - get the genuine FTDI device (i.e. not cheapo chinese knockoff)). No fault codes in the ECU.

Swapped the thermostat - Also spent a fortune on coolant as I didn't clean the surfaces on the thermostat housing as well as I should have...!!!
Now runs at a steady 90/91degC & idles at approx 690/700rpm (which I believe is high - should be closer to 600).

New NGK plugs all round.

Cleaned the MAF with appropriate cleaner - no idea if it was dirty to begin with - regardless, it should be as clean as it can be.

Still to do:
1. Check/tweak the MAF resistance as per aRRon's advice.
2. Check the temperature sensor - although I think this may be redundant if the ECU is reading the correct temperature.

Cheers

So, I filled it up (took 40L for 110km!!!).
Then tweaked the MAF resistance from 480ohms to 80ohms, and drove the car 100km (combination of 30 hwy/70 city).

I have noticed a few things since tweaking the MAF:
1. It seems like the engine is more responsive, and the auto seems to take a bit longer to change through the gears (i.e. car revs higher compared to the same road speed). Not sure what's happening here as I have no experience with auto boxes.
2. The idle when warm settles down to close on 600rpm when in D. Drifts up to 700rpm when in N or park.

And then!
I then filled it up 91ulp... 35 litres for 100km! This is just madness!

I'm driving with a light foot and can't understand what's the deal. It doesn't help that I think everything is going fine until the fuel gauge jumps between 3/4 full and half full and back again after the first 1/8-1/4 of the tank is used.

I still have to check the compression (missed that comment before).

**Mercguy** · 6th February 2017, 11:43 AM

Have you checked the valve timing? i.e. turned over the engine, checked the rockers are opening at the correct angle? Quite a common issue - worn camshaft, crook lifter (usually get a pretty average tick noise in the valley) and worn rockers. You won't need a degree wheel, but if you have one, it can help. (print one out on your computer and stick it to some cardboard /metal/plastic if you can't buy one) Basic engine 101 stuff. Make sure your timing is set correctly, make sure your camshaft has correct lift. (forget about rocker ratio factors and other crap, you just want to make sure it's opening and closing at exactly the correct moment. any obvious wear on the crest of a cam lobe will be evident at max lift when using a dial gauge on the rocker shaft (pushrod side).

Even though hydraulic lifters are designed to eliminate repetitive valve lash setting, they will not compensate for a worn camshaft. A worn cam means less lift at the valve, which equates to inefficient induction - or basically asthma for an engine. i.e. it might be breathing, but it's not getting the oxygen (and fuel) that it needs. So while the ECU is shoving the fuel down it's throat, there's not enough air to complete the efficient combustion, which basically means it's running rich. Too rich. and because it's not making power effieicntly, you sink the boot in to make it move, which just drops more fuel in.

Check your plugs. are they fouled? sooty? even wet? that's another sign.

fuel pressure regulator can also be stuffed. That's something that you'd troubleshoot after you checked your EFI basics (i.e. timing, spark, then air/fuel)

Make sure you have a good well lubed and CLEAN dizzy as well. I don't mean new cap and lucas rotor, I mean check under the cover that the hall sensor and trigger are clean and you have the correct clearances. Check the vac advance is working. Make sure the advance weights aren't stuck or sticking... Ensure the static advance is set to around 12deg btdc. No other vacuum leaks etc.

If you haven't seen the bee-utey distributor module relocation thread, I heartily suggest you also undertake this, simply as part of basic rover v8 maintenance - then you can cross ignition issues off your 'list' of things to check.

It's not really a complicated setup. Just treat the engine as if it were 3 separate systems. inspect and diagnose them separately - A mechanical air pump, a fuel system and an ignition system. if you can be sure everything is functioning within spec, then you'll solve the problem. The trouble is, you will not know until you check and verify each individual system.

These things will actually 'run' with a lot of lattitude / tolerance for wear and even obvious fault. What many people don't actually realize, is that just because an engine idles smoothly, or 'makes power' or even 'tows good' does not mean it's actually functioning within spec.

The efi thing isnt meant to confuse. In reality it is simply a fuel metering device, which is 'timed' instead of being constant. When the sensors are tested (follow the test procedure) and found to be within specification, you move to the next component and test it. When everything is found to be within spec, then you place the system 'under load' and take some sample values from the sensors / components whilst under load and compare those to the specification. If they fall outside the spec, replace them.

In the 14CUX system, the obvious areas to look at are the MAF sensor (clean and correct resistance values), the temp sensor (correct values over range of operation - i.e. cold, warm, hot) and the resistance of the two injector loom banks (4-4.5Ω each side). Then the idle air bypass / idle speed controller (back of plenum) is clean and functioning. That's not everything, but it's a good place to start your checks.

for the fuel system, fuel pressure, fuel filters and fuel pump, as well as the hoses (kinks/rot/blocked etc) will have an effect. If you want to test for leaking injectors, ign on, have the fuel rail and injectors removed from the manifold, and observe for leaks. they should not leak at all, but there is a 'limit' in the manual which says maximum of 2 drops per minute from any injector. I'd suggest that if you see any leaks within 5 minutes, count them and then have the injectors cleaned ultrasonically / reconditioned / replaced (depending on your budget).

Ignition system is simple. new plugs in the correct heat range. a GOOD set of leads (magnecor is quite possibly the best set you can lay your hands on, or genuine bosch - not anything PRC made) and then pay attention to the distributor module and it's wiring (clean terminals, good wire) and the mechanical function of the distributor itself (rebuilding one is not a difficult job, but mechanical sympathy helps). Again, Bee-utey's thread is worth reading, and setting your static ignition timing to approx 12deg btdc will make a difference.

Lastly.... despite what people say to the contrary, avoid the use of ethanol-additive fuels. All this will do is serve to prematurely rot the fuel system, gum up the injectors, absorb moisture and cause internal rust and because of the octane rating and the fact the engine was never designed to burn it, a noticeable increase in fuel consumption. So stick to 95 as a minium and where possible run 98, to ensure your fuel system is clean and free of crud. 98 also allows you to dial in more advance if you want.... but watch your temps!

Over on the british v8 org site there was a reference to the rover 14cux efi system, but there are also heaps of other sources, including RAVE, and plenty of experienced mechanically minded members here who can help.

good luck with resolving your issues, I often find breaking things down into the simplest segregated form helps to troubleshoot, and often leads to a straightforward diagnosis.

**drover81** · 10th February 2017, 01:03 PM