Misfiring issue

Ok so I have a 95 rr county lwb 4.2l v8 and I'm having a recurring misfire issue. Basically to start out about 4 to 5 months ago I went out for a drive and couldn't even accelerate because it starting misfiring so bad. Come to find out the distributor cap had corrosion in one of the connections and I cleaned it off it didn't go away so I ordered a new one and problem solved. Well now about 2 weeks ago it came back I checked the distributor cap.. no corrosion so I pulled the spark plugs (which only had 700 miles) and they were black cleaned them with a wire brush and checked the gap everything was good and it fixed the issue for about 2 days then it came back worse than before. So I went and bought a new set of spark plugs and it fixed it again. Didn't come back until yesterday now it's back again but not as bad as before just slight here and there and sometimes it does it worse on cool damp mornings. I'm out of ideas. the spark plug wires only have about 2k on them.

Sounds like it could be overfuelling to me?

Wazzajnr said:

Sounds like it could be overfuelling to me?

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How would I go about testing that?

welcome t the club... see my thread on classic misfiring https://www.landyzone.co.uk/land-rover/misfiring-at-2-3000rpm.309292/

NoobieRover said:

How would I go about testing that?

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Is it carbs or FI?

Lots of possible causes. As above, it does sound like it is reappearing when the plugs foul. Maybe you could rule out lambda sensors if symptoms can occur during warm up and after the car switches to lambda control.
http://www.actproducts.co.uk/2011/l...n-system-–-installation-and-diagnostic-notes/

Can you de-coke them heads without taking them off ?

Wazzajnr said:

Is it carbs or FI?

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its fuel injection on that.. lucas hotwire

noobie rover.

I've had a similar issue as you'll see from the thread above and the steps I have taken. your system does have an early form of diagnostics, not OBD but a 3 pin that gives you rudimentary fault codes and diagnostics.. I bought a system called rover gauge its about $50..

where I am up to with it now is that the distributor has an issue.. maybe needing pulling the dizzy and rebuilding or replacing. i'm getting evenly fouled plugs across all 8 too and reading overfueling on the O2 sensors through rover gauge.

You say it's worse on cool damp mornings, does it improve any as the car warms up? If so, it could be the coolant temp sensor giving a bad reading.

Wazzajnr said:

Is it carbs or FI?

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Fi

Wazzajnr said:

You say it's worse on cool damp mornings, does it improve any as the car warms up? If so, it could be the coolant temp sensor giving a bad reading.

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Replaced the coolant temp sensor that's what I was think originally when it came back this last time.. sorry forgot to mention that

ukadamwest said:

noobie rover.

I've had a similar issue as you'll see from the thread above and the steps I have taken. your system does have an early form of diagnostics, not OBD but a 3 pin that gives you rudimentary fault codes and diagnostics.. I bought a system called rover gauge its about $50..

where I am up to with it now is that the distributor has an issue.. maybe needing pulling the dizzy and rebuilding or replacing. i'm getting evenly fouled plugs across all 8 too and reading overfueling on the O2 sensors through rover gauge.

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Where is the so called plug at? I am intrigued! I will definitely look into that what all can it read through it?

NoobieRover said:

Where is the so called plug at? I am intrigued! I will definitely look into that what all can it read through it?

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under the front seat next to the fuel ecu and fuel pump relay.. it looks like this

ukadamwest said:

under the front seat next to the fuel ecu and fuel pump relay.. it looks like this

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alright sweet can you send a link to rover gauge

NoobieRover said:

alright sweet can you send a link to rover gauge

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sure

http://home2.btconnect.com/stevesprint/remap-14cux/gadgets.html

This is what the spark plug looks like! Keep in mind this spark plug doesnt even have 50 miles on it!!!

that's over fuelling !

you're not wrong

This article may give you some pointers. I've only skimmed it but it seems well written.
http://www.britishv8.org/articles/rover-14cux-efi.htm

NoobieRover said:

How would I go about testing that?

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The EFI ECU controls the fuelling based on the various sensors, testing the workings within the ECU isn't a diy function, but as the EFI coolent/engine temperature sensor is the most common one to fail and will cause over-fueling when engine is up to temperature, this can be tested, resistance data on that and sensors can be found on the LRV8 engine sites (such as mentioned in the post above) and Forums... or replace it.

Just to add: if over-fuelling on a cold start indicated by lots of black smoke then the ECU is/ or maybe faulty, as I found out in my 3.5 days, main Dealers didn't have a replacement so I took it to Lucas and they bench tested and repaired it while I waited, those where the days when Lucas was everywhere but still cost £100 for the repair.