Have a 2007 BMW Z4m Coupe which seems to be impossible to get through the Rolling Road Fuel economy test in Taiwan This is the 5th time its failed…just. Another 30,000NT bites the dust 
So close,we are only a few percent away,however we have tried most things ECU wise (hard to stop Knock sensor overide) .
My last thought is that maybe a longer final drive CWP may just help it scrape through. The Physics say it should but I am not sure?
Sulavaca…maybe you have an idea? I know M3 after 2009 is ok but earlier M3s are registered? Any help appreciated.
I assume this is for one-off “type approval” for a personal import, since AFAIK fuel economy isn’t normally tested. How do they test it?
I suppose you’ve already got the thinnest, most friction-modified, high-techest-but-not-necessarily-any-good-in-the-long-term lubricants throught, otherwise you wouldnt be contemplating changing the final drive.
Bigger wheels? Just on the verge of exploding tyre pressures?
IF they tested for emissions and fuel economy separately that’d give you quite a lot of scope for leaning since you wouldn’t need to keep the cat cooking.
Higher octane fuel, achieved by additives? (eg methanol, toluene or acetone, IF the plastics are compatible short term. There are probably more sophisticated alternatives ?) - you mention knock as a limiter.
I would presume the same thing.
There is a method and means to get this car through it’s inspection, however it will cost money and is done by professionals. This will typically cost a few tens of thousands of NT, will require a number of parts to be borrowed and then returned.
We have done this before to BMWs and Porsche imports, but I’m afraid this is one of the secrets most garages are not willing to give up.
The thing is though, that emissions tests are often pretty easy to circumvent using small adaptions to the exhaust.
Pretty much all you need to do is create a periscope shaped pipe from some small pipe and weld it into the exhaust pipe. This can be done pretty much anywhere in the system, but preferably towards the rear of the vehicle, after at least one silencer and where noise is less present and the gas pressure lower. This will be a venturi in effect, with the same effect as within a carburettor.
When fitted correctly, this periscope shaped pipe will sit fairly hidden from view, and will allow the outside air to be drawn into the rushing exhaust gasses thus diluting the gasses down to an adequate level. The periscope, or 90 degree shape in the pipe is only to help eliminate some noise which will result, and also allow the pipe to be longer than if it were straight.
I have seen one Mercedes ML fitted with several of these pipes, which have even been left in place after testing, and no excessive noise is prevalent at all.
You can experiment by yourself, but you will need an original exhaust system to play with as this will be inspected during the test. Otherwise, as I say, you can take the car to a professional workshop and have the work and the test all done for you.
DP
Perhaps it’s time to buy a more fuel efficient car?
I think it’s time that the Taiwan government stopped trying to protect local manufacturers so much from outside competition.
This doesn’t have anything to do with fuel economy per se.
[quote=“Ducked”]I assume this is for one-off “type approval” for a personal import, since AFAIK fuel economy isn’t normally tested. How do they test it?
I suppose you’ve already got the thinnest, most friction-modified, high-techest-but-not-necessarily-any-good-in-the-long-term lubricants throught, otherwise you wouldnt be contemplating changing the final drive.
Bigger wheels? Just on the verge of exploding tyre pressures?
IF they tested for emissions and fuel economy separately that’d give you quite a lot of scope for leaning since you wouldn’t need to keep the cat cooking.
Higher octane fuel, achieved by additives? (eg methanol, toluene or acetone, IF the plastics are compatible short term. There are probably more sophisticated alternatives ?) - you mention knock as a limiter.[/quote]
Many thanks,
Alas, we have to check all cars (seperately) for emms.check …easier as Sulavaca mentions…but there is an economy test ,under load,on a rolling road which ,as implied in another reply,does not help economy. it simply ,makes the odd model almost impossible to pass. Some very economical cars fail if their CCs are too small as the test is linked to engine size.
I have the same problem with some new cars…somebody .in an office. has decided on a rule.which is stricter than almost every other country!,for…er…no practical reason…the car is fine in all other countries…even USA …California. 
I wonder,when i see the old scooters smoking away,and this is actually a pretty "clean " car :loco:… then i remember I am in Taiwan 
We have friends with a Lamborghini which is not able to pass the test…looks pretty in the showroom though.
[quote=“shiadoa”].somebody .in an office. has decided on a rule.which is stricter than almost every other country!,for…er…no practical reason…the car is fine in all other countries…even USA …California.
I wonder,when i see the old scooters smoking away,and this is actually a pretty "clean " car :loco:… then i remember I am in Taiwan
We have friends with a Lamborghini which is not able to pass the test…looks pretty in the showroom though.[/quote]
Taiwan makes these cars fail only because it tries its hardest to block competitive imports. It is buddying up to local businesses which also produce or import gas guzzlers, but at a profit. Most of them have lobbyist groups or invest in potential government runners.
It is quite possible to pass your car though, and like I say, if you can’t do it yourself, then you will have to pay a specialist garage to do it for you. Perhaps after I get back, I can help sort it out if you need help.
[quote=“shiadoa”][quote=“Ducked”]I assume this is for one-off “type approval” for a personal import, since AFAIK fuel economy isn’t normally tested. How do they test it?
…Etc see above…
Higher octane fuel, achieved by additives? (eg methanol, toluene or acetone, IF the plastics are compatible short term. There are probably more sophisticated alternatives ?) - you mention knock as a limiter.[/quote]
Many thanks,
Alas, we have to check all cars (seperately) for emms.check …easier as Sulavaca mentions…but there is an economy test ,under load,on a rolling road which ,as implied in another reply,does not help economy.[/quote]
Don’t mention it. Obviously I’m just making this up, unlike Mr S
How do they measure the fuel consumption? If its an actual volumetric measurement on the FI intake, perhaps you could “cheat” by bleeding propane into the air induction path, to augment your fuel.
I have this rigged (with a lighter refill canister) on my Skywing (OK, sublime - ridiculous transition, you choose) since I managed to accidentally disable the choke while fiddling with the carburettor (old technology, look it up) .
Its visible, but if anyone cared it’d probably be easy enough to hide.
That’s under manual control though. If you have to leave the car with THE MAN for testing the on/off would have to be automated (perhaps with a solenoid) otherwise you might blow the car up. Sorting that out may be more trouble than paying the fixers.
EDIT: I suppose you could, alternatively, inject a little supplementary liquid fuel. If you remove the air filter that might give you some room to hide stuff. If it was controlled by the air flow, perhaps via a venturi, in effect a primitive carburretor, it could be self-contained, avoiding the requirement for any external control inputs. ENDEDIT
Soak the Evaporative Control System charcoal cannister (assuming its got one) in petrol?
Dunno what its capacity or delivery profile would be, but you might be able to open it up and replace the contents with something more “efficient”.
I’d guess you’d want something like a reservoir/wick combination. I suppose you might be able to use something like that inside the air cleaner as well, if you could live with the fire risk.
All these “ideas” assume that emissions are tested separately from fuel economy, so are not a concern, which I think you said was the case.
[quote=“Ducked”]Soak the Evaporative Control System charcoal cannister (assuming its got one) in petrol?
Dunno what its capacity or delivery profile would be, but you might be able to open it up and replace the contents with something more “efficient”.
I’d guess you’d want something like a reservoir/wick combination. I suppose you might be able to use something like that inside the air cleaner as well, if you could live with the fire risk.
All these “ideas” assume that emissions are tested separately from fuel economy, so are not a concern, which I think you said was the case.[/quote]
Possible,The Tests are seperate. I am still trying to work out if changing the final drive (to longer gearing) would work. It should in theory. Although i love your ideas on this ,most ideas involve the possibility of an explosion :fume: :discodance: LOL
Well you have a point. My job entails driving this car for passenger laps,sliding around etc, for various Events we do on Racetracks and also some Instructing.
My work requires me to burn up Fossil fuels sometimes, although indirectly,Vehicle Energy recovery systems developments have been accelerated by Motorsport.
Reminds me of an old Rowan Atkinson comedy sketch with the initial line being "The Devil…is He all bad? "
Sure. The probabality would, however, depend on the implementation, and I THINK needn’t be very high.
Anyway, us Cold War babies got used to the possibility of an explosion a long time ago. 
Havn’t tested this, just an idea:
Disposable lighter inside the air cleaner, with a vane (perhaps cut from a CD?) glued to the tap-lever thingy. Car starts, airflow pushes against the vane (enough pressure? too much obstruction? removal of filter enough compensation for the obstruction?), lighter valve opens, gas introduced into the induction path.
EDIT:Most lighters have adjustable flame length/gas delivery, giving you some “tuning” capability, though you’d probably want it turned up to the max. If one wasn’t enough, there might be room for more than one unit.
NOTE: You do NOT want a piezoelectric ignition lighter here. That’d be an IED.
ENDEDIT
Of course the capacity of a disposable lighter is rather small, so you’d probably have to plumb it in permanently to a refill source, probably via the refill port. Doing and concealing that supply plumbing might not be so easy.
EDIT: You can, however, get smallish clear plastic refill gas ampoules which might have enough capacity to be useful while being small enough to conceal in the air filter housing(I’ve got one somewhere). You could probably clamp one directly onto the lighter, perhaps backing up the seal with a bit RTV silicone. Again, there might be room for more than one unit. ENDEDIT
I’m assuming this car is electronically controlled, so a simple mechanical linkage to, say, the throttle cable isn’t practical.
By chance I got a look at the analyser screen when I was in for my half year vehicle inspection today. 4.7 % CO, 7.2% CO2, IIRC. Didn’t see the HC but presumably high (They don’t give you a printout, probably the thinking is “no numbers, no pack drill” stylee).
The posted limits for a 1990 car (mines 1986 which wasn’t posted) are 4.5% and >9%, so that should probably have been a fail, but the private centres tend to cut you some slack for the repeat bizniz, and their meters are allegedly “tuned” to read low anyway.
I was reminded of this post, however, and it doesn’t seem to me that this procedure would work in this case, since there’s a minimum % of CO2 specified, and diluting with air would reduce the CO2 %
Perhaps it works with the different limits specified for newer cars?
I checked the UK MOT emission limits online. (Havn’t found the Taiwan ones, but I’d expect them to be similar but perhaps introduced later. It appears from a quick look that, in at least some US states, a car of this age might be exempt)
gov.uk/government/uploads/s … Edition.pd
The CO limit shifted from 4.5% to 3.9% during 1986, but there is no mention of a minimum CO2 value. Perhaps I got it wrong (or the test centre poster was wrong) but it seemed pretty clear.
If its correct, the implication is that Mr S’s emissions test avoidance technique would work in the UK (which is good, because I might actually need it there. Might be hard to hide the plumbing from a UK MOT tester though.) but wouldn’t work in Taiwan, (which probably doesn’t matter so much, since it doesn’t seem to be so necessary to pass here.)
This seems like a really old thread that was revived…
but I would say put some full size spare wheels/tires on it.
The higher profile skinny tires and lighter wheel/tire combination should decrease your rolling resistance quite a bit on dynamomoter rollers.
The final drive won’t make much difference really unless it’s geared really really low to start with.
Beyond that, I don’t know what’s up with your knock sensor but stock ECU/ECMs don’t like it one bit.
Get a wideband and see how far off your tune is under the test’s simulated speed/gearing (I assume its a constant speed/load?), then tune it properly.
Shouldn’t be too hard.
[quote=“zads27”]This seems like a really old thread that was revived…
but I would say put some full size spare wheels/tires on it.
The higher profile skinny tires and lighter wheel/tire combination should decrease your rolling resistance quite a bit on dynamomoter rollers.
The final drive won’t make much difference really unless it’s geared really really low to start with.
Beyond that, I don’t know what’s up with your knock sensor but stock ECU/ECMs don’t like it one bit.
Get a wideband and see how far off your tune is under the test’s simulated speed/gearing (I assume its a constant speed/load?), then tune it properly.
Shouldn’t be too hard.[/quote]
The car passed by changing rear diff to a different ratio one…sorry I forgot to update on here. You can not change the Tyre Profile or wheel size from standard for the Test. Wish it was all that easy. My next challenge is our Caterham test which we almost have ready. After probably 60,000 uSD of tests and an amendment of a crazy old Law They have an electro magnetic interference Test where they fire a signal at the car to make sure things are stable. As the Caterham has virtually no electronics like airbag ( the real reason for the test) the signal from the speed sensor and wiring is not shielded, hence the speedo flicks up slightly .
We will have to shield and maybe earth the sensor etc. Meanwhile the Government has taken another 6000USD for that test and we have to pay the same again for a re-test 
[quote=“shiadoa”]
The car passed by changing rear diff to a different ratio one…sorry I forgot to update on here. You can not change the Tyre Profile or wheel size from standard for the Test. Wish it was all that easy. My next challenge is our Caterham test which we almost have ready. After probably 60,000 uSD of tests and an amendment of a crazy old Law They have an electro magnetic interference Test where they fire a signal at the car to make sure things are stable. As the Caterham has virtually no electronics like airbag ( the real reason for the test) the signal from the speed sensor and wiring is not shielded, hence the speedo flicks up slightly .
We will have to shield and maybe earth the sensor etc. Meanwhile the Government has taken another 6000USD for that test and we have to pay the same again for a re-test [/quote]
Shiadoa, you’re either a real early riser, a vampire like me, or out of the country… 
Wow, you’re dedicated to that Caterham- good to hear you are, though.
6000 USD for a EMC test :loco: :loco:
On the bright side, since the Caterham is so minimal in general (including the electronics), at least the speedo wiring should be very easy to separate/isolate and shield.
Modern car wiring harnesses are such a huge PITA to work with…
Good luck!
[quote=“zads27”][quote=“shiadoa”]
The car passed by changing rear diff to a different ratio one…sorry I forgot to update on here. You can not change the Tyre Profile or wheel size from standard for the Test. Wish it was all that easy. My next challenge is our Caterham test which we almost have ready. After probably 60,000 uSD of tests and an amendment of a crazy old Law They have an electro magnetic interference Test where they fire a signal at the car to make sure things are stable. As the Caterham has virtually no electronics like airbag ( the real reason for the test) the signal from the speed sensor and wiring is not shielded, hence the speedo flicks up slightly .
We will have to shield and maybe earth the sensor etc. Meanwhile the Government has taken another 6000USD for that test and we have to pay the same again for a re-test [/quote]
Shiadoa, you’re either a real early riser, a vampire like me, or out of the country…
Wow, you’re dedicated to that Caterham- good to hear you are, though.
6000 USD for a EMC test :loco: :loco:
On the bright side, since the Caterham is so minimal in general (including the electronics), at least the speedo wiring should be very easy to separate/isolate and shield.
Modern car wiring harnesses are such a huge PITA to work with…
Good luck![/quote]
I thought I would get my own back on the slave drivers by not sleeping at all. I live In Taichung but deal with California a lot so I stay up until 4 or 5 am, then go to the office from 1pm until…late. We have a new Race series for next year and building a Racetrack, so will announce that at our new showroom on 17th May in Taichung. Have to entertain CEO of Caterham etc, etc and pay for 22 new Race cars…ouch. :s Life is not so easy at the moment 