Exhaust emissions hydrocarbon content is excessive

I have taken my Discovery 3.5 V8i 1990 to a garage for a MOT and have been told the 'Exhaust emissions hydrocarbon content is excessive) its 2352 (it should be below 1200). I have been told it may be the engine misfiring.

There is a story before this, the car started idling poorly then one day cut out and wouldn't restart, after a little investigation it turned out to be the fuel pump.

After about a month I finally got round replacing it and at the same time I changed the fuel filter spark plugs and leads.

The car started perfectly and seemed to run fine but after a few trips I noticed it was drinking more petrol than before, I was getting about two thirds the mpg.

There are no petrol leaks and added with the high emission I suspect it could have been something I did.

Any suggestions?

Well, if it is missing, then I would check all your leads and plugs, you should be able to check for the missing cylinder by putting a little wax on each part of the exhaust manifold if you can get at it, the one that doesnt melt off at the same time as the rest, is your culprit.

Then I would whip the plug out and check it and its lead. When the plug is out, make sure the plug is wet with fuel, I would expect it will be if its hydrocarbons emissions problems you are having.

V8i - Could also be a problem with a fuel injector(s).

Also do a dark test on the leads. Start the engine & look at the leads in the dark & see if any are tracing to earth or any are glowng i had a problem with a V8 disco with the leads & got Landys own & it sorted the missfire. Does it run ok at idol/tickover or does it rev up & down if so you need to be in the air flow meter & adjust in there. If it is i have one i can send pic's of where to adjust it. Or if any parts needed i am breaking a 3.5 v8 E,reg

CHIPPED TD5 said:

Does it run ok at idol/tickover or does it rev up & down if so you need to be in the air flow meter & adjust in there. If it is i have one i can send pic's of where to adjust it.

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When its idling the revs are erratic and has a tendency to cut out so a pic would be great.

I will take some in the morning & send you them if you could send me an e-mail address to send them to.

Have tried the wax test and the melting was pretty uniformed so I have taken all the plugs out and checked them individually.

All the plugs are fouled equally, my guess is a weak spark.

One other thing I have noticed is a large amount moisture coming from the exhaust but it only appears to be water and not petrol.

I need a few opinions.

I am convinced the problem above isn't due to a misfire and i know it isn't due to oil that leaves a few main cuprites:

1. My battery has gone flat again so that needs replacing, could that have cause a weak spark causing the fuel not to be burnt completely.

2. the injectors, I have put some injector cleaner in with my fuel and the idle seems to have stabilized. There again the idle seemed to fluctuate once the engine was warm anyway.

3. Faulty or incorrectly set air flow meter.

Any thoughts or idea's would be very much welcome.

Well you were helpful as ever!

The problem is now sorted and the V8 now has its grunt back.

The solution is as follows.

1) The air flow meter had been taken of at some point and not put back on correctly leaving a slight gap.
2) Took all the leads and plugs off, cleaned them put them back together and sprayed a little WD40 on the terminals on the leads (a little trick I learned from my scooter)
This all helped but was still a little high.
3)Took it to a garage that specializes in land rovers and 4 x 4's, he popped out a little cap on the engine to reveal a screw to adjust to air/fuel mixture (didn't even know you could do this on a EFi version) and bobs your uncle it runs perfectly, connected up the emissions tester, another quick test and 700 parts per million, not quite the 600 that means perfection but beats the minimum of 1200 to pass.

As a bonus the engine runs better and now sounds like a V8!

If you live in the West Bromwich, Smethwick, Langley or Oldbury area there is a very small garage called :
H & H Auto Service,Mallin St, Smethwick, West Midlands B66 1QZ Tel: 0121 558 4483

He really knows his Land Rovers.