Hi there wondering if anyone can help me , my partners 899cc seicento has failed its mot on emissions (have uploaded a copy of results). I had it plugged into a diagnostic and said the injector was reading a fault so replaced the complete throttle body and gave car service (oil,air filter , spark plugs and oil) .

When taking old one off you could see light around the edges of the valve that opens and closes , on the new one you can't . This helped the cars idel to be quieter but hasn't actually helped emmisions. Have been told it's not the cat that's cause the fail , also had the lambada sensor replaced about 2 years ago.

Does anyone have any ideas as what's causing this emmisions to fail so bad ?

hi sorry about your fail. Don't know what would cause high emissions on your car but have heard of very good results from something called cataclean which you put in your fuel tank. It claims to reduce emissions by up to 60% so it might be worth a go
Stephen

I would only try something like Cataclean as a desperate last measure. A friend of mine tried some for his emissions and it changed nothing, a waste of about £16.
Can't help otherwise sorry as you seem to have done the more obvious things already.

Ian.

Bear in mind that the engine needs to be quite hot for the CAT to actually do anything on these cars as it's so far away from the engine, take it for a fast thrash about before the test and try to get them to test the emissions ASAP to ensure that the CAT is hot enough.

As said give the car a good thrashing before it's goes back for its retest I can't stress this enough, the amount of cars I've seen fail at work just because it's been drove straight to the mot station cold is unreal if it fails again then could mean new cat time but I have seen something simple like a coolant temp sensor to play up causing the car to run rich throwing the emmisions out

Do you have any leaks on the exhaust system

I'd hook it up to diagnostics to check if lambda works at all. The lambda readings tell me it's not, or they tested it on a drastically cold engine (had idiots at my local garage try to do it to me once ).

Forgot to mention that the garage originally thought it might have been coolant sensor so that has been replaced to.
I don't believe ther to be any holes in exhaust will double check to see if it blowing anywhere tomorrow.
I read on another thread saying to give the car a 40min run to relearn not to over fuel as mainly used for short trips would that actually help reset ecu or anything?

Holes in the exhaust usually cause lean lambda readings, not rich.

Your problem might as well be lambda not functioning (or simply disconnected / badly connected). Taking guesses by mechanics like "it might be a coolant temp. sensor" without checking with diagnostics is just plain ripping off clients.

You may try getting it to adapt, but I am 95% sure that rich running means something wrong with engine control. A correctly functioning lambda does not let the engine run rich, adapted or not.

When plugged into diagnostic it was a fault with the injector that came up that's why we changed throttle body . Which on sound of the car sounded like it had fixed but when checked emmisions it was still a fail.

The coolant temp did help one of the readings but not as much as they hoped for.

Eklipze3k said:

Bear in mind that the engine needs to be quite hot for the CAT to actually do anything on these cars as it's so far away from the engine, take it for a fast thrash about before the test and try to get them to test the emissions ASAP to ensure that the CAT is hot enough.

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Yep.
As the Cat is a long way from the engine it takes a long time to get hot and cools quite quickly.
Mine needs holding at high revs for quite a long time to get the Cat to light up and start working. Once in that window the emissions quickly drop and pass, but it takes an understanding MOT tester to do that, many wont bother and will just fail it...

The Lambda reading in the emissions test is a calculated reading in the machine, based on the gas analysis, so is showing that the exhaust is showing an engine running rich, or with insufficient air.

As suggested above, the oxygen (lambda) sensor may be not working properly. Being only two years old may not be relevant. Any replacement needs to be a good brand name with the correct plug already fitted. Avoid one you have to solder, as it is easy to get a poor soldered joint and interfere with the small voltage change readings it produces. Ideally it needs a diagnostic reading of the oxy sensor to check its functionality.

Rich running is either excess fuel, or insufficient air.
Simplest first. Does it need a new air filter?
Different throttle body. New, or used. Is it just different rather than better? Make sure it is clean.
Coolant temp sensor is important. Are there two? Not sure of this engine, but with many engines there are two sensors, one for the temp gauge, another for the engine management.
A diagnostic check should show the readings of all the sensors and these can be compared with what is expected. Does the intake air temp sensor reading match the current air temp? Is the coolant temp reading appropriate for the time the engine has been running? A sticky thermostat can cause it to run cooler than it should.

Excess fuel can be a dribbling injector, or fuel pressure too high.

Any more thoughts anyone?

Have checked over the car can't see any leeks in exhaust .
I took it out for a drive along some country roads to warm it up and on my returning trip the car felt a bit jerky and hesitant to accelerate
(I know it's not got lots of power but you could definitely tell it wasn't as fast as when first went out)

Would this be caused by faulty lambda ?

I checked inside air box to make sure it had opened up to allow more air which it did . I also checked both top and bottom part of radiator hoses and was both hot (so no stuck thermostat or anything)

Also I have found the receipt for the lambda it was 2012 so 3 year old not 2

DarrenClark said:

Have checked over the car can't see any leeks in exhaust.

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As said above, any leaks in the exhaust will give a lean reading, not the rich reading you have.

There are two temperature sensors on the 899 engine.
One on the thermostat for the ECU
another on the other end of the head for the gauge (or warning light in this case).

Which sensor did they replace?
Once hot, does it run better with the sensor on the stat unplugged?

Yeah thought id check condition of exhaust just to be sure whilst it was jacked up.
The sensor they replaced was the one on the head I believe .
Have had it car checked over again today an multimeter plugged in on sensor for lambda and wasn't giving correct readings so believe this to be the problem.

After taking it of noticed it was rather grubby looking , have ordered a new one should come tomorrow so see what that brings

Does the engine burn some oil?

Dirty sensor could be soot form oil burning, or from rich mixture. Could be cause or effect.

Probably duff sensor, causing rich fuelling, so depositing soot on the sensor, making it worse. Hopefully new one will sort the problem.

As teh garage seem to have replaced the temp sensor that has no effect on engine fuelling, perhaps they might like to refund that cost, or do the retest for free.

Not really known it to use a lot of oil to be honest .
Car seems to be misfiring a little so possibly causing over fuelling giving higher hydrocarbons as well.
Have checked to see what sparks are coming out and seemed to be a poor spark on number 3 (I believe) even though they brand new. Have been told to see what it's dark to see if any damage to leads .So will check when it's dark to make sure there no arcs in ht leads or anything.

A leak in the exhaust before the lambda will cause it to over correct and run rich, a leak after the lambda will just bugger up the readings they get on the machine.
I'm not familiar with euro 4 regs, I think we are on now. How much is it failing by? Loads or not much?

I would just cheat. Pull up at the test station, whip the air filter out plus that hot air feed, which does bugger all. Drive into the test station like a gran in tescos, keeping the revs at about 3000 and get them to bung the probe up straight away. Tell them you're battery isn't great and you're worried about it not starting again.

I mean what do they expect, that engine helped power the ark for gods sake. Just because you stick fuel injection and a cat on it, doesn't mean it's going to burn any cleaner.

Huwbishop said:

I'm not familiar with euro 4 regs, I think we are on now. How much is it failing by? Loads or not much?

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It doesn't need to pass current regs.

The default on the machine is for current cars, but if it can't pass that it goes to a specific test for that car with higher limits.


There is a printout of his result in the first post.

Almost have Emmisions sorted it's gone from being 200times over the limit to only 3 times , the CO2 was reading at 0.9-1.02 ish there or thereabouts (0.3 being limit) dud run the car for 30-40 min prior to test

To get this we had stripped down engine and soaked tappets over night in petrol which freed them up. Also fitted a new lambda sensor which helped .

The tester mentioned about a vacuum pipe that looked perished which could be the problem. So I looked into it and seen that it's the map sensor pipe which is looking perished. And seeing as it's going to the ecu which is controlling fuel ect I'm thinking that this could be what's caused it to still over fuel slightly . Does anyone know where to get a replacement part from ?
Iv attached some photos too .
Also can anyone tell me what the black connector is , is it a flash protector or something?