Excellent advise as always chaps

I didn't think about corrosion and dry joints. I will probe about with the multimeter and see if I can get the lid off of the ecu and check it out inside.

I've resoldered a few rover 800 fuseboxes, but I'm guessing this would require a lot more precision.

I also assumed that the ECU would be like a modern IC based jobbie!

Anthony

Ok, I had the ECU apart and there's no corrosion to the main connector, not inside. I couldn't see any dodgy looking solder joints, nor any blackened components.

I also found a handy pin-out in the Haynes manual so I can test continuity and voltage. I haven't done that yet because I had a bad headache and peering at wires upside down in the passenger footwell was making me go cross-eyed

The distributer was taken apart. The pick-up wheel was rather corroded and one of the weights for the mechanical advance was rather sticky. The two springs for the weights were also different sizes and one looked stretched. I'm not sure if this is correct (it may well be) but we're going to try and get some more from Rimmers, along with a circlip that broke on removal.

Anthony

Greetz...

I couldn't find any spare parts for V8 distrbutors. I hoped a big landrover/rangerover mail order place would have such a thing, but sadly not.

A replacement for the broken circlip was obtain from a local bearing/gear supplier.

I've got a secondhand distributor on the way and will hopefully get another soon for comparison and spare parts.

I did a continuity test from the ecu connector to the airflow meter, coolant temp sensor and the throttle position sensor. All proved to be good at .001-.002 ohms.

Supply voltage to the ECU was 11.35v with the engine off. This is 1.5v less than battery voltage. I see in the Haynes that the ECU is feed through a "line resistor", which is shown to be seperate to the fuel pump ballast resistor. What voltage should the ECU get? I also couldn't see an earth pin in the haynes diagram.

The timing was set to 5* BTDC and the same problem still exists. Reverting the mixture screw on the AFM from 2.5 turns to 4.5 turns (as the car originally was), lowered the idle speed, but made no difference to the problem.

Viewed with the timing strobe the mechanical advance works and when the vac advance is connected it makes the response faster.

Continuity from ignition amplifier to coil is 100%

I'm starting to lean back towards this being an ignition problem...

I have to say though, that when the dissy was initially refitted the timming was very far advanced (about 30* BTDC) and the car started much quicker than normal.

Thanks Ramon. I've now confirmed voltage feed to ECU (pin 10 from memory) is 0v with ignition off, and 12v with ignition on. Pin 1 is 0v ignition off, but 2.7v with ignition on and engine not running.

I don't know if this is normal. I'd guess the sensor/pickup works like an ABS sensor with a variable voltage caused by the peaks on the wheel in the dissy?

I've also refitted the ballast resistor to the fuel pump which made no change.

I've refitted the original coil, although I had to guesstimate at the LT connections as my wiring diagram helpfully didn't specify. I'm hoping it doesn't matter. No idea which side the little condensor attaches to either. That produced no change anyway.

I've checked the resistance of the coolant sensors at the sensor and then at the ECU multiplug, the results were only a few ohms different (at 1000 ohm reading). I found a 270 ohm resistor that I'm going to swap for the sensor and see if it makes any difference. At this point the battery gave out so I didn't get to see the result.

A different rotor arm has also been tried, along with cleaning the distributor cap, which made no difference. I'll get another cap and another set of leads to try. I've got a landrover ECU and airflow meter on the way to try.

I may also reduce the plug gap from 0.8mm to 0.7mm (Is 0.8mm correct for the EFI? Haynes only specifies for the carb engines).

I'd just like to evoke some kind of change so I can know if this problem is fuel or ignition related!

On starting the car there is a slight miss at idle that can be felt as an engine vibration and heard at the exhaust. The engine revs up fine in idle and the it no longer chokes when the accelerator is opened suddenly (I hate this car).

It drives ok for about 1/2 mile until the temp gauge reaches 80-100*C then it will just miss badly as soon as any load is put on the engine (like climbing a slightly hill). Progress is limited to about 5mph in 1st gear as you find somewhere to turn around. Pulling away is then only possible by dipping the clutch, revving to 4-5k (which it does ok) then gently feeding in the clutch. You can then limp/coast home. Although the engine may cut out while missing, but will restart readily.

Anthony, I would ignore the pin 1 reading as its not a valid test with ign on and ign not running.

If you are guessing at the ign wiring then anything could be wrong here, but what else might be incorrectly wired?

for coolant temp sensor test go here, paragraph 22

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or in more detail this.

Readings should be approximately as follows
TEMP---- OHMS
-10°C -- 9100 to 9300
0°C-- 5700 to 5900
20°C-- 2400 to 2600
40°C-- 1100 to 1300
60°C-- 500 to 700
80°C-- 300 to 400
100°C-- 150 to 200

If the readings are incorrect its prolly faulty.

Your symptoms at hot engine temp suggest a rich mixture so the sensor may be telling the ECU the engine is cold when it is actually hot.

What are the plug conditions like when that happens? Sooty?

Ramon

Punx0r wrote:

Thanks Ramon. I've now confirmed voltage feed to ECU (pin 10 from memory) is 0v with ignition off, and 12v with ignition on. Pin 1 is 0v ignition off, but 2.7v with ignition on and engine not running. I don't know if this is normal. I'd guess the sensor/pickup works like an ABS sensor with a variable voltage caused by the peaks on the wheel in the dissy? I've also refitted the ballast resistor to the fuel pump which made no change. I've refitted the original coil, although I had to guesstimate at the LT connections as my wiring diagram helpfully didn't specify. I'm hoping it doesn't matter. No idea which side the little condensor attaches to either. That produced no change anyway. I've checked the resistance of the coolant sensors at the sensor and then at the ECU multiplug, the results were only a few ohms different (at 1000 ohm reading). I found a 270 ohm resistor that I'm going to swap for the sensor and see if it makes any difference. At this point the battery gave out so I didn't get to see the result. A different rotor arm has also been tried, along with cleaning the distributor cap, which made no difference. I'll get another cap and another set of leads to try. I've got a landrover ECU and airflow meter on the way to try. I may also reduce the plug gap from 0.8mm to 0.7mm (Is 0.8mm correct for the EFI? Haynes only specifies for the carb engines). I'd just like to evoke some kind of change so I can know if this problem is fuel or ignition related! On starting the car there is a slight miss at idle that can be felt as an engine vibration and heard at the exhaust. The engine revs up fine in idle and the it no longer chokes when the accelerator is opened suddenly (I hate this car). It drives ok for about 1/2 mile until the temp gauge reaches 80-100*C then it will just miss badly as soon as any load is put on the engine (like climbing a slightly hill). Progress is limited to about 5mph in 1st gear as you find somewhere to turn around. Pulling away is then only possible by dipping the clutch, revving to 4-5k (which it does ok) then gently feeding in the clutch. You can then limp/coast home. Although the engine may cut out while missing, but will restart readily.

My Vandenplas has developed the same problem just now.I'll follow this thread and see can i resolve it.

Thanks for the figures Ramon. I had a good look at all the plugs - they look completely fine. Tan coloured electrode with the threaded section black, but not all fouled up. I regapped all the plugs (some were a little off) and retightened the little threaded aluminium caps (some were slightly loose), checked the plug lead order and routing, rechecked the timing and took the car for a run.

It was already warm from the timing when I took it out, but had stood for about 20 mins. I got about a mile of going round the block before it started missing and headed back home in first gear at 2000rpm.

As I pulled up to a stop to reverse into the small car park the car was missing heavily at idle but I noticed the rev counter was jumping from 1000rpm (idle speed) to 0rpm about once a second. As I reversed the car into its space it stalled, just died as though the ignition had been switched off. I restarted it and the rev counter went straight to 1000 then to 0 and the engine died just as before, jabbing the throttle had no effect. I tried this twice more with the same affect, gave up and pushed the car myself. The car has not been this bad before.

I believe the problem is with either the ignition amplifer, or the pickup sensor inside the distributor. Without a proper signal the coil won't fire, hence no spark. I also think that brief loss of signal is possibly interrupting the fuelling. I suppose that extended loss of signal leads the ecu to believe that the engine has stopped and cuts the fuel completely. This explains the engine dying so gracefully (key out), and why the plugs don't show fuel starvation or fouling as the engine is being deprived off both.

I'd also bet that the rev counter is powered by the coil pulse, I can't see any other place it could get an engine speed signal.

The problem seems very much like crank sensor failure on a MEMS controlled rover.

I'm now looking for a replacement complete distributor, and hopefully will post when I find out if it's cured the problem! I'd like to think so, this missfire is something that I can now see has gotten progressively worse.

Kerosene it would be interesting to see if your rev counter also becomes erratic whilst the missfire occurs?

Anthony

Time for an update

I bought a landrover lucas 35DLM8 distributor and swapped the ignition amplifer onto the current dissy - missfire cured! Hooray!

This unfortuantely led to the rediscover of an older running problem that was noticed when the car went for it's MOT's (including one run where the problem dissapeared and the car ran perfectly). A refusual to rev over a certain engine speed (varying between 2k-4k), or hesitation/no power at moderate throttle openings. Occasionally resulting in backfire, occasinally stalling, but then working ok after a restart.

I tried:

Switching between fuel pump ballast resistor and bypass fuse - no change

Checked fuel delivery at engine bay - seems good, filled a saucepan in 20 sec and pressure good if I put my finger over the end of the pipe (sprayed everywhere).

Swapping coolant temp sensor for a 200 ohm resistor, and checked resistance at the ECU multiplug - no change

Swapped ECU for a landrover item - no change

Swapped whole distributor for landrover item* and reset timing - no change

Clamped hose feeding air rail - no change

Added two more gallons of petrol to the tank (car won't make it to the nearest petrol station!) - no change.

Blew threw filter (clean), fuel rail and return hose to tank with compressed air - possible, small improvement

Swapped airflow meter for landrover item - small improvement

Refitted original airflow meter and increase CO screw to 4.5 turns - very small improvement.

Connected pressure gauge to cold start injector hose, results showed normal at idle. However, observing the gauge whilst driving has given the game away. The fuel pressure is correct under sedate driving, but at moderate-heavy throttle the pressure reading falls. It should be ~36psi on full throttle, but I found it fell to 18-20psi and started missfiring. I got it down to 15psi at one point... It once fell to 10psi at idle and stalled.

So I think I have found the final problem...

First suspect is a blockage at the tank. So the tank is going to be drained, removed, cleaned and blown through the air, along with the feed line to the engine bay. This might also explain the noisy fuel pump. I'll also look for collapsed/kinked pipes.

Then the pump itself, or it's power supply (may connect it to a seperate battery).

Lastly the fuel pressure regulator.

Fingers crossed

Anthony

Hi Ramon, yes I measured it at idle and it was ok, 26-28psi at idle and flicking up to 36-38psi with the throttle fully open (just for a second).

I wouldn't say I was any kind of expert, I muddle through with the help of people like yourself who know considerably more about the systems.

The problems I’ve had have been: air leaks, ignition related misfire, and fuel related misfire. All mixed into one big, frustrating pot… The car does start and idle nicely now though and warms up as it should. The throttle pot does still need looking at though.

My dad got a start on the car yesterday afternoon and removed the tank. He drained most of it using the fuel pump to the engine bay, and said that the output was rather weak. The final two gallons poured from the tank were a bit yellow, and there was some grit, but not huge amounts. The tank outlet pipe wasn’t restricted to lung pressure and I blew compressed air through the connections, no blockages. The tank will be rinsed out and prepared for refitting.

Next stop is the fuel pump and pipes, I will be annoyed if the car needs another fuel pump!

I do appreciate the help from this forum, it’s been great