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Mot Test - Exhaust Emissions


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#1 Kevin Wadsworth

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Posted 27 February 2013 - 05:41 PM

For those of you in the UK, I thought you might be interested to know what the current rules are relating to Seras. 

 

My latest Sera is a 1995 model, and I'm wanting to put the stainless steel exhaust from my last Sera on it. Trouble is, my last Sera was a 1991 (no catalyst). 

 

Having read all the rules, it looked to me, like I would be ok, but my local testing station disagreed, saying all post 1992 cars have to have a CAT, and anyway, if I removed the CAT which was fitted as standard, it counts as a modification which isn't allowed.

 

I rang my local VOSA centre to get the definitive answer, and they went through all the small print with me. Happily, I was right, and here's why....

 

All Seras (with or without a CAT), will go through the main emissions test, which all cars have to go through. If the emissions are low enough, you pass. Simples.

 

If you fail, they have to go to their rule book, which says that if their database doesn't have an EXACT match for the vehicle (which it doesn't), then they have to put it through the non CAT test (CO2 threshold 3.5%), which any Sera should walk through.

 

Win, win



#2 Tobias

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Posted 28 February 2013 - 11:56 AM

My latest Sera is a 1995 model, and I'm wanting to put the stainless steel exhaust from my last Sera on it. Trouble is, my last Sera was a 1991 (no catalyst).

 

According to ToyoDIY all Seras ('90-'95) had a catalyst (part no. 18450-16240).



#3 AndrewC

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Posted 28 February 2013 - 12:02 PM

All Seras were made with a catalyst, but different countries have different regulations concerning emissions and several people have removed theirs - perfectly legal to do so.

 

Some people have just taken the old catalyst out and bashed out the catalyst, but have reported this has a detrimental effect on the performance, restored when a piece of straight through tube is placed inside.    Others have made a custom downpipe or have fitted a cat bypass pipe.  

 

However, the MoT test men are often not fully aware of the rules, so need to be told to refer to the test handbook.


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#4 Kevin Wadsworth

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Posted 28 February 2013 - 03:45 PM

Yeah, sorry, I should have said that I hzd the cat removed from my previous Sera when I had the stainless system fitted. No problems with that, as it was a 91 car.

#5 Adam Evans

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Posted 28 February 2013 - 05:09 PM

Why don't you get the stainless exhaust off your old car and put it on your new one.

That's if andrew still has it

As I parked in the disabled bay the other day someone shouted over

 

"Hey, what's your disability ?"

 

I shouted back, "tourettes now F**K OFF !!"


#6 AndrewC

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Posted 28 February 2013 - 06:04 PM

Thats the plan, but Kevin wanted to make sure his 1995 car would be legal...


1992 Toyota Sera ph3 ï1977 Lancia Montecarlo ï 1999 TVR Chimaera ï 2005 Fiat Ducato Motorhome ï Norwich Photo Motorsport Photography ï Racing Exposure ï Facebook ï Twitter ï Instagram


#7 Adam Evans

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Posted 28 February 2013 - 06:07 PM

it will be close enough :P

 

 

just remember to tell the insurance (not telling is illegal) haha


As I parked in the disabled bay the other day someone shouted over

 

"Hey, what's your disability ?"

 

I shouted back, "tourettes now F**K OFF !!"


#8 Adam Evans

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Posted 28 February 2013 - 06:54 PM

P.S Kev it is the CO test that is the problem not the CO2 and anyway no sera will ever be over 3.5%

 

seriously even mine when it had a goosed lambda sensor was still under 2%

 

I did manage to tune it outwards on the gas system to about 9% but the car quickly brought it back into line

 

all seras when given a blast up the road will read under 0.2% but then leave it ticking over for a long period of time and it will fluctuate between 1-2%

 

here is why (boring bit just flick through if not interested)

 

the lambda sensor on a sera is a 1 wire sensor which means it does not have a heater circuit in it.

the heater circuit in a lambda sensor is there to keep the sensor smoking hot at all times, therefore more efficient.

if you blast your car down the road and then watch the lamdba it will fluctuate brilliantly. come to a stop and it wont - it is all over the place

this is because the exhaust is cooled down by then and it is running inefficiently

 

a way to combat this is by fitting a 3 or 4 wire sensor with the heater circuit built in.

this is not "really" recommended - but neither is de-catting your car

what a 4 wire sensor does is makes the car "think" it is up to temp before it actually is therefore from about 5 seconds after you turn the key the car comes out of "electronic" choke

it is still in physical choke and holds onto the gears but it doest it more accurately as the lambda sensor is warmed up almost instantly and knows exactly how much fuel to give the car 100% of the time rather than just dumping in some fuel and hoping for the best

way to wire it in is to take an ignition live to a relay to operate a full 30a heater circuit from the battery

don't worry it is a permanent live you use but it is relayed with an ignition live signal - very simple

 

I have done this to my car and it increased the efficiency ever so slightly but I have noticed that it got rid of the "hunting" at traffic lights when the car is in D with the foot on the brake.

 

 

 

either way if you read that or not just remember that if your car has a 1 wire sensor then kick the overdrive off and smoke it over for an MOT while it is still warm as it has more chance of passing (if there is any doubt)


As I parked in the disabled bay the other day someone shouted over

 

"Hey, what's your disability ?"

 

I shouted back, "tourettes now F**K OFF !!"


#9 Souliere

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Posted 11 November 2017 - 01:51 PM

Thanks for the insights. I had no idea about all the details.





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