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MOT Fail Help

5.3K views 47 replies 12 participants last post by  tommo86  
#1 ·
Hi

I have eventually had the time to finish the MGF project up to mot standard that I started early in the year.

So the car went in the other day and has failed on emissions.

The garage did two fast idle test, first one as follows

CO Level 0.51%
HC Level 99ppm
Lambda 1.03

Now the pass rate for the CO level 0.30%

Second fast idle test results

CO Level 0.36%
HC Level 110ppm
Lambda 1.02

The natural idle test CO Level is 0.48%

So from the looks of things as the car has got hotter/ran more, the emissions did come down a good 0.15%.

The car has had a new head on and replacement piston / sleeve and a complete full service , Russel did the head and piston work so there wont be anything wrong with that. I've put some red ex in half a tank of petrol.

Any other ideas??

Many thanks

Tom
 
#2 ·
As you said the longer the car was ran for the lower the emmisions. I have heard of people over in the 200/25/ZR/Streetwise section taking their car for a spirited drive right before they take the car in to be tested and it has got the emmisions down so that the car can pass.

I think this might be all you need to do but I'm sure someone else will be allong in a while with another suggestion that you could try aswell.
 
#12 ·
Ok results are two faults

02 sensor 1 circuit logged sensor output voltage too high

Inler air temp sensor circuit active fault sensor output voltage


The reading on the 02 sensor was at 4v when running!! , the bloke said it should always be under 1v and changing.

So where about's is the 02 sensor, where can I get a new one from and how hard to fit?

Many thanks

Tom
 
#13 ·
Ok results are two faults

02 sensor 1 circuit logged sensor output voltage too high

Inler air temp sensor circuit active fault sensor output voltage


The reading on the 02 sensor was at 4v when running!! , the bloke said it should always be under 1v and changing.

So where about's is the 02 sensor, where can I get a new one from and how hard to fit?

Many thanks

Tom
Isn't the O2 sensor the Lamda sensor?
 
#15 ·
That's nowhere near an epic fail! http://forums.mg-rover.org/showthread.php?t=432606 is an epic fail ;)

The inlet air temp sensor is easy to remove (once the engine hatch is off) and reasonably easy to test - it looks like this: http://i230.photobucket.com/albums/ee204/macleodaj/MG/P1020878.jpg

There's a thread about it here http://forums.mg-rover.org/showthread.php?t=363423 which gives the resistance at 24 degC to be 1.95 KOhms.

I gave mine a clean with servisol, no idea what's best or if that's harmful but a new sensor is cheap enough and there should be loads of them in scrapyards as the same sensor was quite widely used I believe.

Picture of it in situ here; http://www.mgfcar.de/sensor/air_inlet_temp_sc02208.jpg

By the sounds of it your lambda sensor is probably the bigger problem though...
 
#22 ·
Ok so after struggling with removing the manifold and the o2 sensor I have no managed to change it over and re test tomorrow now for the emissions.

In the proccess of removing the manifold I managed to drop a spanner which wedged itself between the alternator and the subframe, sparks smoke and one very hot spanner . Stupid me forgot to take the battery off :doh:

Now when the car is running the batter light is on, Have I fubared my alternator??


Many thanks

Tom
 
#23 · (Edited)
Ok so after struggling with removing the manifold and the o2 sensor I have no managed to change it over and re test tomorrow now for the emissions.

In the proccess of removing the manifold I managed to drop a spanner which wedged itself between the alternator and the subframe, sparks smoke and one very hot spanner . Stupid me forgot to take the battery off :doh:

Now when the car is running the batter light is on, Have I fubared my alternator??


Many thanks

Tom
I think there's a large fuse somewhere on the engine bulkhead,may be worth trying to see if that has blown..it's shown as the Hypalon fusible cable in this link to Deiter's site http://www.mgfcar.de/schedules/sb12.jpg
 
#32 ·
Ok ,

I've had an emissions specialist come out this morning, his verdict is my ECU is fubared , something about telling the car that its too cold which is making in run to rich??

Anyway is this likely?? And where can I get a working ecu from that doesn't cost ÂŁ600 lol

Cheers

Tom
 
#33 ·
Ok ,

I've had an emissions specialist come out this morning, his verdict is my ECU is fubared , something about telling the car that its too cold which is making in run to rich??

Anyway is this likely?? And where can I get a working ecu from that doesn't cost ÂŁ600 lol

Cheers

Tom
Could be a sensor....does your radiator fan ever come on...if the ecu water temp sensor never gives a "warm" reading then the ecu will think that the engine is still cold....if the rad fan never comes on then this may be a symptom of the sensor failing..I'm sure someone will have a better idea but until then...
 
#34 ·
Did you check the IAT sensor I mentioned earlier in this thread? It's easy to remove and easy to test so worth starting with. Also triple check the vacuum hose that goes from the inlet manifold round the engine/boot bulkhead to the ECU (if your car has it?) for any cracks / chafes / leaks. One leak there was enough to send our car's emissions through the roof, running hugely rich.

I wouldn't start with the ECU myself, start with the cheapest possibilities and work your way up!
 
#42 ·
Ok people still no idea on what to do with this emission problem, I think ill get the car running and do a vid so you can here the slight miss fire and go from there. Need to get this on the road as I need transport asap.

Also turns out I need new pipes underneath, nice little leak and the speedo cable has snapped that goes from the clocks to the bonnet :doh:

Anyway help please!! lol

Cheers
 
#43 ·
Right long overdue update of this car.

Fitted a new Cat and a Back bock I bought from Bobert .

My step dad took it for an mot (its his car anyway) somewhere different to where I took it last. The emissions passed!!! Yeah!!!

But fail on other things. :(

The car now needs passenger side sill and a few other bits of welding. My step dad now has lost interest in the car as it needs a bit of body work tidying up and a new wing as it is bubbly.

So my questions is shall I break it up, re shell it or sell it as it is.

Work done to the car and hasnt done any miles since work done

New brake pads and discs at front
New track rod ends
New Lower Ball Joints
Recon Hubs
A russel worked 1.8 VVC engine (New head, Head Gasket , Bolts, Therm, Waterpump, Cambelt Kit.
New Rear Screen.

Its not a bad looking car and I would be tempted to buy it off him but I have too many cars.

What do you guys think>

Many thanks

Tom
 
#46 ·
Ok so I have bitten the bullet and spent some time on the car.

Have welded the sill and sealed it and is now solid.

Have wire brushed the chassis ,rust proofed and sealed and looks as new, i had a mechanic have a look while it was over the pit and he says there are no holes in it( so not sure what the last mot tester was going on about) so that should be ok.

Sorted out a few other items like clutch bleeding and started on some cosmetics issues so the car is now ready for a re test but.......

Went to start the car up and it started and died :dunno: , it does restart but dies all the time

Sounds like its running out of fuel but the gauge shows 1/4 full and i drove it in there 5 weeks ago.

Any ideas?


Cheers

Tom