Troubleshooting high emissions, where to next?

[Geminidawn]

I have a 99 Freelander 1.8 Petrol that keeps failing the NCT (same as MOT) on emissions. The Hydrocarbon readings and fuel consumption is through the roof and it sets off the carbon monoxide alarm as soon as it drives into the test centre. It seem to be overfueling all the time.

Here what has been done so far:

New Catalytic Converter

New Lambada Sensor

New Cooling Temperature Sensor

Ner Fuel Temperature Sender

New Sparkplugs

Twice tested at Landrover diagnostics center no faults show.

Yet it still fails to pass. Has anyone any ideas because I'm all out and I'd hate to scrap an otherwise perfectly good vehicle because of it.

[marty1a]

Leaky injectors? pressure valve on the fuel pump? - is the compression good on the engine?

[FridgeFreezer]

Check/change the intake air temperature sensor (green one on manifold).

Check for vacuum leaks in the small pipe from the ECU to the manifold, and on the manifold & other vacuum pipes too. This vacuum reading + air/coolant sensors is how the ECU calculates the fuelling.

It's worth checking the voltage coming from the lambda sensor signal wire, if they are fouled up (eg with very excessive over-fuelling) they read low (<0.5v) which fools the ECU into putting even more fuel in. You can often clean them by removing them and heating till the tip glows red with a blowlamp.

[Ally V8]

Where did the replacement Cat come from ? The Cat on a 1.8 K series does alot of work,the cheap aftermarket ones often dont work well enough - even when brand new.If there are no misfires and the black output wire on the Oxygen sensor is cycling between 0 and 0.8v then the cat is almost certainly at fault.(With the engine hot and running at a constant speed.)

[Geminidawn]

Many thanks to all it gives me a few more options to try before I give it the death sentence. I have to admit the Cat that was put in was not top of the range but it did come with a two year "guarantee". Choices for parts are limited for a vehicle of that age over here, I was lucky to find a Cat that would fit as most places stopped stocking them.

I can't see how the Cat would be responsible for the high ammounts of hydrocarbons and unburnt fuel coming out the exhaust though?

[Ally V8]

Hydrocarbons are unburnt fuel,on a K series the Cat has alot of work to do - to save me typing loads of guff do a search on Wikipedia to see how a Cat works.I think its the fairly large valve overlap on these engines that allows quite alot of unburnt fuel to go straight out the exhaust port before the engine has a chance to use it.Unlike a duffy old Rover v8 which hardly needs its Cat if its well set up.

You could always get the garage to test the emissions before the cat by disconnecting it and shoving the probe into the downpipe - this is what I did to prove the rubbish cheapo part was not working.This was when I realised how much work the cat does on a freebie.

[tim_roberts]

The original post said that his fuel consumption was through the roof. that doesn't sound like a cat problem to me, something much more fundamental that LR diagnostics ought to be able to pick up.

[FridgeFreezer]

I'm with Tim - eye-wateringly rich emissions would not be saved by a better cat, I ran my 1800 without a cat and it never smelt bad or strongly of unburnt fuel.

[Ally V8]

We really need to know what the actual emission readings are and what the Oxy sensor is saying, without those we are all just guessing.

[marty1a]

Compression test the engine,

injector leak test

Something is wrong with the engine not the cat.

If you need injectors pm me i no where there is a freelander being broke up in the north and the guy is great to deal with

[JonT]

Try looking on the MGRover.org forum, under MGF/TF - it's the same engine, and if you do a search I would be surprised if you did not find something relative to your problem - it is a very busy forum, and the regulars are also very helpful !!

[marty1a]

Is the exhuast smokey?

[FridgeFreezer]

We really need to know what the actual emission readings are and what the Oxy sensor is saying, without those we are all just guessing.

If it's managing to hose that much fuel down the exhaust we can take a pretty good guess that the O2 sensor is either railed at 1v or drowned at 0v.

Even with a disintegrated cat, the emissions aren't *that* high if everything else is working as it should be.

[Ally V8]

Yes,all good stuff - but the op has just stated that the emissions are too high - but in what amount ? Is the Co at 0.6 or 6% - makes a big difference as to where you look for the cause.Is the Oxy sensor telling the ecu its as rich as hell or is it dead in the water at zero? Till we know what the actual readouts were all this banter is a bloody waste of time.

[FridgeFreezer]

<cough>

The Hydrocarbon readings and fuel consumption is through the roof and it sets off the carbon monoxide alarm as soon as it drives into the test centre.

[Ally V8]

Yes - but what were the failure readings ? Through the roof can mean anything - Look at the original post,the car has had the parts shotgun fired at it,with some of the usual suspects,with no result.Twice checked on LR diagnostics with nothing found.So whats going on ? If the Co and HC are at a really high figure - say 10% and 5000 ppm then A,it would stink and B it would log at the least an Oxygen sensor fault.Neither have been mentioned.So did the LR centre get it wrong or is the situation not as described ?

High fuel consumption - yes,but are the brakes sticking on,seen plenty of those this winter,the farm next door has been running around a TD4 with both front calipers siezed for the last two months,just as an immediate example.Setting the alarm off as soon as it goes into the garage - if it has such an alarm,none of the 50 odd garages I work for here in the UK have such a thing,(Sounds like a good idea tho)then you have to wonder what the tech who did the original dignostic checks was up to.

Another thought,early Mems ecu's are not the most reliable,I've seen them ignore Map readings and both under and over fuel - its another possibility.

I thought these forums were supposed to be helpful,but some of Fridges comments recently have been far from it.

I'll say it again,without more info about the actual emissions from the test its difficult to be specific.

[Ally V8]

Suggesting the Cat may be at fault was just that - a suggestion.You see the thing is we still dont have any proper data to work from,

[FridgeFreezer]

IMHO chasing around removing the cat & measuring emissions is going to be a waste of the OP's time & money,

when there are more basic things further up the chain to check that can be done for free by eye or using nothing more advanced than a multimeter.

Edited February 11, 2011 by western

[Ally V8]

.All we have for now is that it has failed its emission test,(But no actual test results)the fuel consumption has gone up,(But no figures)a list of shotgun parts wasted on it and that its come through two diagnostic tests with a clean bill of health.

Was it a main dealer or a respected indy that did the work ?

Were leads,cap and rotor tested ?

Fuel pressure tested ?

Does it run on 4 ?

Is the timing correct and belt correctly tensioned ?

Has anyone even looked at the oxy sensor output ?

These are just few

Edited February 11, 2011 by western

[Hybrid_From_Hell]

[admin Hat On]

ENOUGH

You have been warned, keep it civil squabbling is Banned here

Like it or lump it, ENOUGH

[/admin hat off]

[western]

Thread amended to remove the slanging match, which isn't required.

Stay on topic or further action will result. keep it friendly.

[western]

one thing nobody has suggested is the test centre emission testing kit working correctly ??

[Ally V8]

one thing nobody has suggested is the test centre emission testing kit working correctly ??

I guess the increased fuel consumption means something is going on,but seeing as the op hasnt responded to any further suggestions its not going to help.Thank you for editing my posts.