BBWF - MOT type emissions test
Discussion
All,
If anyone is interesed - I'm going to be bringing my portable 4 gas analyser to the BBWF.
The MOT regulations are :
Car manufactured 1/8/75 and 31/7/86 - meter test CO <=4.5%, HC<=1200ppm.
Car manufactured 1/8/86 and 31/7/92 - meter test CO<=3.5%, HC<=1200ppm.
So - if anyone wants to know what it puts out .. we can test it and maybe a few experts like wedgie can suggest ways to improve the figures..
Like below :
Basic fault finding for advanced emission test failures:
1. If a vehicle fails for high CO at idle and /or fast idle then.... if Lambda is too low, the mixture is too rich. This can be caused either by a misfire or by a faulty Lambda sensor. If it's running very rich, the 02 and HC will be higher than normal.
2. if it has a high Lambda and high 02 (0.5 to 1.5%), the "CAT" could be faulty. Before condemning it make sure its hot enough to work, the Lambda and other sensors are working OK and the exhaust downpipe hasn't got any leaks.
3.if the vehicle fails for high HC then ...if the CO passes, the vehicle is probably misfiring. Or if the CO fails and the Lambda reading is too low, the mixture is probably too rich and it may also be misfiring.
4. if the CO fails, the Lambda reading is high and the O2 reading is high (0.5 to 1.5%) the "CAT" could be faulty. Again check out the simple measures above before condemning it.
5.if the Lambda fails then...if its too high the Lambda sensor may be faulty, the mixture may be too weak or there may be a hole in the exhaust downpipe. If Lambda is too low the sensor may be faulty, the mixture may be rich or the vehicle may be misfiring.
If anyone is interesed - I'm going to be bringing my portable 4 gas analyser to the BBWF.
The MOT regulations are :
Car manufactured 1/8/75 and 31/7/86 - meter test CO <=4.5%, HC<=1200ppm.
Car manufactured 1/8/86 and 31/7/92 - meter test CO<=3.5%, HC<=1200ppm.
So - if anyone wants to know what it puts out .. we can test it and maybe a few experts like wedgie can suggest ways to improve the figures..
Like below :
Basic fault finding for advanced emission test failures:
1. If a vehicle fails for high CO at idle and /or fast idle then.... if Lambda is too low, the mixture is too rich. This can be caused either by a misfire or by a faulty Lambda sensor. If it's running very rich, the 02 and HC will be higher than normal.
2. if it has a high Lambda and high 02 (0.5 to 1.5%), the "CAT" could be faulty. Before condemning it make sure its hot enough to work, the Lambda and other sensors are working OK and the exhaust downpipe hasn't got any leaks.
3.if the vehicle fails for high HC then ...if the CO passes, the vehicle is probably misfiring. Or if the CO fails and the Lambda reading is too low, the mixture is probably too rich and it may also be misfiring.
4. if the CO fails, the Lambda reading is high and the O2 reading is high (0.5 to 1.5%) the "CAT" could be faulty. Again check out the simple measures above before condemning it.
5.if the Lambda fails then...if its too high the Lambda sensor may be faulty, the mixture may be too weak or there may be a hole in the exhaust downpipe. If Lambda is too low the sensor may be faulty, the mixture may be rich or the vehicle may be misfiring.
Here are some MOT testers notes / guidelines .. as an fyi :
A. All vehicles
1. Raise the engine speed to around 2500 rpm or half the maximum engine speed if this is lower.
Hold this speed steady for 20 seconds to ensure that the inlet and exhaust system is properly purged. Allow the engine to return to idle and the emissions to stabilise.
a. assess the engine idle speed.
b. assess the smoke emitted from the tailpipe at idle,
c. rapidly increase the engine speed to around 2500rpm or half maximum . engine speed if this is lower and assess the smoke emitted from the tailpipe. Allow the engine to return to idle.
_________________________________________
The test should be conducted with the engine warm. Testing a cold engine could lead to an unjustified failure.
It is important to ensure that any enrichment device is not operating.
The engine should be idling normally during the test and should not be subject to significant electrical loading such as heated seats or heated rear windows.
If an engine will not idle, an assistant may apply light throttle pedal pressure.
To assess that these conditions are met, MOT Testers can either
. Use their own judgement, or
. Refer to manufacturer's or other reliable data
______________________________________________
A holed exhaust can allow air to be sucked in, causing artificially low readings.
Where a vehicle has an exhaust holed to the extent that MOT failure is warranted, the emissions should be rechecked when the exhaust is repaired even if the vehicle does not leave the testing station in the meantime. Owners should be made aware that any emission readings taken with a leaking exhaust might be incorrect.
Holes not justifying MOT failures do not normally have a significant effect on the exhaust gases at the tailpipe and can be ignored.
___________________________________________
A. All vehicles
1. Raise the engine speed to around 2500 rpm or half the maximum engine speed if this is lower.
Hold this speed steady for 20 seconds to ensure that the inlet and exhaust system is properly purged. Allow the engine to return to idle and the emissions to stabilise.
a. assess the engine idle speed.
b. assess the smoke emitted from the tailpipe at idle,
c. rapidly increase the engine speed to around 2500rpm or half maximum . engine speed if this is lower and assess the smoke emitted from the tailpipe. Allow the engine to return to idle.
_________________________________________
The test should be conducted with the engine warm. Testing a cold engine could lead to an unjustified failure.
It is important to ensure that any enrichment device is not operating.
The engine should be idling normally during the test and should not be subject to significant electrical loading such as heated seats or heated rear windows.
If an engine will not idle, an assistant may apply light throttle pedal pressure.
To assess that these conditions are met, MOT Testers can either
. Use their own judgement, or
. Refer to manufacturer's or other reliable data
______________________________________________
A holed exhaust can allow air to be sucked in, causing artificially low readings.
Where a vehicle has an exhaust holed to the extent that MOT failure is warranted, the emissions should be rechecked when the exhaust is repaired even if the vehicle does not leave the testing station in the meantime. Owners should be made aware that any emission readings taken with a leaking exhaust might be incorrect.
Holes not justifying MOT failures do not normally have a significant effect on the exhaust gases at the tailpipe and can be ignored.
___________________________________________
honourablepickle said:
i'm too frightened to get a probe up my pipe
we had to set a "fast idle" (about 2500rpm ) to get my car through MOT the other week !
hp
I had the same problem with my 400. The garage did so much messing to get through the hydracarbon test it took me ages to get the car drivable again.we had to set a "fast idle" (about 2500rpm ) to get my car through MOT the other week !
hp
Bloody MOT's
Ok thank you.
I think you posted that 1-2% is best setting.
I know to get full performance your need it mapped, just wondered if they was a optimum setting that was not within the MOT range, as I know the MOT guy and he will set it to what ever I want after the MOT. and just adjust every time for me to get it to pass. (nice bloke to know
I think you posted that 1-2% is best setting.
I know to get full performance your need it mapped, just wondered if they was a optimum setting that was not within the MOT range, as I know the MOT guy and he will set it to what ever I want after the MOT. and just adjust every time for me to get it to pass. (nice bloke to know
TVRleigh said:
Ok thank you.
I think you posted that 1-2% is best setting.
I know to get full performance your need it mapped, just wondered if they was a optimum setting that was not within the MOT range, as I know the MOT guy and he will set it to what ever I want after the MOT. and just adjust every time for me to get it to pass. (nice bloke to know
1 to 2 % will be just fine..I think you posted that 1-2% is best setting.
I know to get full performance your need it mapped, just wondered if they was a optimum setting that was not within the MOT range, as I know the MOT guy and he will set it to what ever I want after the MOT. and just adjust every time for me to get it to pass. (nice bloke to know
Getting a power run on a good rolling road that also lists the AFR will tell you if re-mapping is needed.
Seems that standard RV8 EFI engines (and mine is 350i standard) produce most power with about 4,0% CO stationary, but 3,5% will probably be fine for power and mine is now setup like that. Think that lower CO is for economics and perhaps the engine can run lean if you then push it.
All if memory serves me right....
Rob
All if memory serves me right....
Rob
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