MOT after Engine Swap - Emissions rules
Discussion
I'm on my third try at an MOT after two failures due to emissions. My car is a BMW Z4 E85, 2.0 (originally) that I've modified with a Chevy 6.2L LS3, plus gearbox, etc. My problem is that each MOT station seems to have a different approach. What I've heard to date:
1) You can't use anything other than the engine on the logbook
2) You have to use the emissions for the year of the car regardless of engine
3) You base the emissions on the engine alone provided you can prove its age
My favourite is 3) but I'm getting told 1) and 2) a lot.
Obviously, if they use 2007 2.0L BMW emissions values they're somewhat less than a 2012 Chevy SS 6.2L (which is the equivalent car/ year for the drivetrain), hence the problem.
Anyone know the actual rules and if there is something online from the DVLA I can quote? I've looked but so far drawn a blank.
1) You can't use anything other than the engine on the logbook
2) You have to use the emissions for the year of the car regardless of engine
3) You base the emissions on the engine alone provided you can prove its age
My favourite is 3) but I'm getting told 1) and 2) a lot.
Obviously, if they use 2007 2.0L BMW emissions values they're somewhat less than a 2012 Chevy SS 6.2L (which is the equivalent car/ year for the drivetrain), hence the problem.
Anyone know the actual rules and if there is something online from the DVLA I can quote? I've looked but so far drawn a blank.
lifted straight from the mot manual.
Vehicles fitted with a different engine
If a vehicle first used before 1 September 2002 is fitted with an engine that’s older than the vehicle, you must test it to the standards applicable for the engine. The vehicle presenter must have proof of the age of the engine.
If a vehicle first used on or after 1 September 2002 is fitted with a different engine, you must test it to the emissions standards for the age of the vehicle.
looks like its option 2 then.
https://www.gov.uk/guidance/mot-inspection-manual-...
Vehicles fitted with a different engine
If a vehicle first used before 1 September 2002 is fitted with an engine that’s older than the vehicle, you must test it to the standards applicable for the engine. The vehicle presenter must have proof of the age of the engine.
If a vehicle first used on or after 1 September 2002 is fitted with a different engine, you must test it to the emissions standards for the age of the vehicle.
looks like its option 2 then.
https://www.gov.uk/guidance/mot-inspection-manual-...
sassanach0 said:
lifted straight from the mot manual.
Vehicles fitted with a different engine
If a vehicle first used before 1 September 2002 is fitted with an engine that’s older than the vehicle, you must test it to the standards applicable for the engine. The vehicle presenter must have proof of the age of the engine.
If a vehicle first used on or after 1 September 2002 is fitted with a different engine, you must test it to the emissions standards for the age of the vehicle.
looks like its option 2 then.
https://www.gov.uk/guidance/mot-inspection-manual-...
Yeah but it's not clear on if it's a different make of engine. For example, the garage tried to find a 6.2l BMW engine for the emissions info. One garage said it needed to be the date of the manufacture of the engine, in my case 2012.Vehicles fitted with a different engine
If a vehicle first used before 1 September 2002 is fitted with an engine that’s older than the vehicle, you must test it to the standards applicable for the engine. The vehicle presenter must have proof of the age of the engine.
If a vehicle first used on or after 1 September 2002 is fitted with a different engine, you must test it to the emissions standards for the age of the vehicle.
looks like its option 2 then.
https://www.gov.uk/guidance/mot-inspection-manual-...
fatbutt said:
sassanach0 said:
lifted straight from the mot manual.
Vehicles fitted with a different engine
If a vehicle first used before 1 September 2002 is fitted with an engine that’s older than the vehicle, you must test it to the standards applicable for the engine. The vehicle presenter must have proof of the age of the engine.
If a vehicle first used on or after 1 September 2002 is fitted with a different engine, you must test it to the emissions standards for the age of the vehicle.
looks like its option 2 then.
https://www.gov.uk/guidance/mot-inspection-manual-...
Yeah but it's not clear on if it's a different make of engine. For example, the garage tried to find a 6.2l BMW engine for the emissions info. One garage said it needed to be the date of the manufacture of the engine, in my case 2012.Vehicles fitted with a different engine
If a vehicle first used before 1 September 2002 is fitted with an engine that’s older than the vehicle, you must test it to the standards applicable for the engine. The vehicle presenter must have proof of the age of the engine.
If a vehicle first used on or after 1 September 2002 is fitted with a different engine, you must test it to the emissions standards for the age of the vehicle.
looks like its option 2 then.
https://www.gov.uk/guidance/mot-inspection-manual-...
The emissions limits that a 2007 BMW engined car have to pass are exactly the same as those for a 2007 car with a Chevy engine.
smokey mow said:
fatbutt said:
sassanach0 said:
lifted straight from the mot manual.
Vehicles fitted with a different engine
If a vehicle first used before 1 September 2002 is fitted with an engine that’s older than the vehicle, you must test it to the standards applicable for the engine. The vehicle presenter must have proof of the age of the engine.
If a vehicle first used on or after 1 September 2002 is fitted with a different engine, you must test it to the emissions standards for the age of the vehicle.
looks like its option 2 then.
https://www.gov.uk/guidance/mot-inspection-manual-...
Yeah but it's not clear on if it's a different make of engine. For example, the garage tried to find a 6.2l BMW engine for the emissions info. One garage said it needed to be the date of the manufacture of the engine, in my case 2012.Vehicles fitted with a different engine
If a vehicle first used before 1 September 2002 is fitted with an engine that’s older than the vehicle, you must test it to the standards applicable for the engine. The vehicle presenter must have proof of the age of the engine.
If a vehicle first used on or after 1 September 2002 is fitted with a different engine, you must test it to the emissions standards for the age of the vehicle.
looks like its option 2 then.
https://www.gov.uk/guidance/mot-inspection-manual-...
The emissions limits that a 2007 BMW engined car have to pass are exactly the same as those for a 2007 car with a Chevy engine.
It might be worth finding what part of the emissions test it is failing on as there may be an issue- lambda values should be the same for a v8 or a 2.0l 4 cylinder, same with hydrocarbons, co levels could be a little different- but it still stands that if it can’t pass the BET test there may be something actually wrong
fatbutt said:
So I should be able to use the data for a 2007 ls3 6.2? I think there was a 6.2 in the 2007 corvette as the Camaro wasn't around then.
If you can prove to them the age of that engine, which would likely require a letter or something from GM linking the engine number to a manufacture date, then yes.Although are requirements for a 2012 engine really that much different to a 2007 ?
This is just a problem with swapping stuff in modern cars.
There is a label on the engine block that states the date as 03/12 and I have the receipt from Chevy saying when I bought it (it was new from them, its not from a donor). This was what Halfords recommended which I thought was sensible. The only problem was they they couldn't get the car on their ramp (exhaust too low) so I have had to progress with other MOT stations which has lead to all the different interpretations of the law.
Elliot2000 said:
It might be worth finding what part of the emissions test it is failing on as there may be an issue- lambda values should be the same for a v8 or a 2.0l 4 cylinder, same with hydrocarbons, co levels could be a little different- but it still stands that if it can’t pass the BET test there may be something actually wrong
fatbutt said:
The only problem was they they couldn't get the car on their ramp (exhaust too low)
It might be easier to solve that logistical problem than to deal with the issues the other MOT stations are raising.Any chance of helping it on to their lift with a couple of low ramps that you could provide? I'm imagining a couple of pieces of scaffolding board, or something along those lines.
smokey mow said:
As this is an engine swap I’m assuming your using an aftermarket Ecu? Are you still running on the base map or have you had the car on a rolling road prior to the MOT to correct the map and get the engine running at its optimum for your installation?
Nope, I bought the E-ROD package from Chevy so you get the engine and ECU (and harness) ready to fit to any car. I had it all previously fitted to my last project car. I scrapped that car, kept the drivetrain and put it in the Z4 
Getting the engines ECU to talk to the BMW ECU was... interesting. The engine swap took weeks, the ECU side took months.
GreenV8S said:
It might be easier to solve that logistical problem than to deal with the issues the other MOT stations are raising.
Any chance of helping it on to their lift with a couple of low ramps that you could provide? I'm imagining a couple of pieces of scaffolding board, or something along those lines.
Halfords, as surprisingly good to me as they were, did actually try hard to get it on there but couldn't. I'd have got in there with scaffolding poles as levers if they'd let me but its a new garage and tied by their rules.Any chance of helping it on to their lift with a couple of low ramps that you could provide? I'm imagining a couple of pieces of scaffolding board, or something along those lines.
Looks like I may have an agreement with the garage! We all agree that trying to match the engine with anything BMW is a non starter so we're treating it more like the kit car rules and following 3). They've given me the printout of the emissions and I'm now going to check them against what an LS3 6.2L car of 2012 is supposed to get. If they match they might/ should say the CO side is ok.
The lambda side is very likely my crap welding on the exhaust with pin holes a-go-go so the garage are going to try to improve all my joints.
If this gets it passed I'll put up the final solution. If not I'll share the woe.
The lambda side is very likely my crap welding on the exhaust with pin holes a-go-go so the garage are going to try to improve all my joints.
If this gets it passed I'll put up the final solution. If not I'll share the woe.
Yep, it's got cats and everything; should be EURO 5 compliant.
I've just spent the last few hours trying to make sense of the emissions results I have. Doesn't help that the emissions info I have is in mg/km but the MOT results are in %.
I was of the impression that the CO value was linked to the engine size but I've just found some thread where they published the results and their limits were the same i.e. 0.2 for fast idle. So, does anyone know if the CO max limit is 0.2 for all engines at fast idle or should it go up for my larger capacity?
Worth noting, the thread had a 2.0L BMW just like the Z4 original engine! So this might be an indication that the garage, even though it says 6200cc at the top of the sheet might be using 2.0L max limits.
For info:
Engine temp: 84 Deg C
1st fast idle: CO result 0.61%, max limit 0.20% FAIL
2nd fast idle: CO result 0.51%, max limit 0.20% FAIL
Natural idle: CO result 0.19%, max limit 0.30% PASS
Editted to add:
https://assets.publishing.service.gov.uk/governmen...
Page 6 states that CO limits are 0.2% at fast idle, 0.3% at normal. So, CO max values are not influenced by the engine size so that point is moot. Its a problem with the car...
I've just spent the last few hours trying to make sense of the emissions results I have. Doesn't help that the emissions info I have is in mg/km but the MOT results are in %.
I was of the impression that the CO value was linked to the engine size but I've just found some thread where they published the results and their limits were the same i.e. 0.2 for fast idle. So, does anyone know if the CO max limit is 0.2 for all engines at fast idle or should it go up for my larger capacity?
Worth noting, the thread had a 2.0L BMW just like the Z4 original engine! So this might be an indication that the garage, even though it says 6200cc at the top of the sheet might be using 2.0L max limits.
For info:
Engine temp: 84 Deg C
1st fast idle: CO result 0.61%, max limit 0.20% FAIL
2nd fast idle: CO result 0.51%, max limit 0.20% FAIL
Natural idle: CO result 0.19%, max limit 0.30% PASS
Editted to add:
https://assets.publishing.service.gov.uk/governmen...
Page 6 states that CO limits are 0.2% at fast idle, 0.3% at normal. So, CO max values are not influenced by the engine size so that point is moot. Its a problem with the car...
Edited by anonymous-user on Saturday 1st February 20:12
Might be an important point: the cats are new. I've not really driven the car and not 'broken them in', which is something I've just learned should really be done for them to work well. Given the results where the 2nd run had a lower CO value than the first, maybe I need to break the cats in and rev it for a while?
As far as I understand it, the cat "break-in" is mainly to give the substrate a gentle heat-cycle to improve its mechanical durability. I wouldn't expect it to affect the ability to convert gases.
Do you have the rest of the gas readings? The CO figures suggest it's running rich. Are you in a position to see what the ECU thinks is going on at idle?
Do you have the rest of the gas readings? The CO figures suggest it's running rich. Are you in a position to see what the ECU thinks is going on at idle?
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