Why decat doesn't work on late MK 7

[limitedblack]

Late MK 7 have VNT turbos, basically a turbo that varies boost with variable vanes electronically, the EGR system is there to control emissions, but the downside of this is a lower mpg, so it uses sensors and software to control the oxygen/fuel mixture to maximise mpg and minimise nox. Part of this calculation is back pressure in the exhaust manifold to control the turbo boost. The result of this is decating the exhaust upsets the control of VNT turbos. Due to the ecu we have on the transits no map is available to compensate for this change in back pressure. At least we know why now

http://www.dieselnet.com/tech/engine_egr_control.php

[Hallii]

Thanks for this, my exhaust is getting a bit rusty and I was contemplating having a stainless one made up and removing the cat at the same time. It is a motorhome exhaust so is likely a specific design (side outlet).

Any idea of the year the changes were made?

Geoff

[loot]

I agree with you there ltd, only reason I would consider a decat or bigger cat is if I increased the volume of air coming out of the engine from standard.( if it was being restricted)

[belly]

How long before Mr Black slots in new management ? I will give a Transporter a go one day

[Damien89]

Late MK 7 have VNT turbos, basically a turbo that varies boost with variable vanes electronically, the EGR system is there to control emissions, but the downside of this is a lower mpg, so it uses sensors and software to control the oxygen/fuel mixture to maximise mpg and minimise nox. Part of this calculation is back pressure in the exhaust manifold to control the turbo boost. The result of this is decating the exhaust upsets the control of VNT turbos. Due to the ecu we have on the transits no map is available to compensate for this change in back pressure. At least we know why now

http://www.dieselnet.com/tech/engine_egr_control.php

When you say "late mk7 have vnt turbos" , how much late? From which year did they change to vnt turbos?

Thanks

[blue estate]

Late MK 7 have VNT turbos, basically a turbo that varies boost with variable vanes electronically, the EGR system is there to control emissions, but the downside of this is a lower mpg, so it uses sensors and software to control the oxygen/fuel mixture to maximise mpg and minimise nox. Part of this calculation is back pressure in the exhaust manifold to control the turbo boost. The result of this is decating the exhaust upsets the control of VNT turbos. Due to the ecu we have on the transits no map is available to compensate for this change in back pressure. At least we know why now

<SPAN class=skimwords-unlinked>http://www.dieselnet.com/tech/engine_egr_control.php</SPAN>

When you say "late mk7 have vnt turbos" , how much late? From which year did they change to vnt turbos?

Thanks

All mk7 140 2.2/2.4 have vvt turbos and I think the euro 5's do

[Hallii]

So a 130PS 2.2 should be OK to de-cat?

Geoff

[Damien89]

Ok thanks then it doesn't affect 115ps if i remove the cat.

[Guy88]

the 130, 140, 200 have VNT for sure

Have a look at the turbo and see if theres any wiring going to it

[limitedblack]

How long before Mr Black slots in new management ? I will give a Transporter a go one day

Is this you?

[Rumble bee]

How long before Mr Black slots in new management ? I will give a Transporter a go one day

Is this you?

Don't think so. Missing the black wheels, fly eye headlights and the private plate. Unless it's an old pic?

[limitedblack]

Who else sea grey sport pasting posters must be

[motorman116]

the 130, 140, 200 have VNT for sure

Have a look at the turbo and see if theres any wiring going to it

Do does this mean that I can de-cat mine, as mine is a 100 ps model and the turbo is controlled by vacuum or by pressure into the little cylinder, and not by electronic motor ?????

[g-man]

loads of vans/cars with vnt's run better and a lot cleaner with decat's

[limitedblack]

the 130, 140, 200 have VNT for sure

Have a look at the turbo and see if theres any wiring going to it

Do does this mean that I can de-cat mine, as mine is a 100 ps model and the turbo is controlled by vacuum or by pressure into the little cylinder, and not by electronic motor ?????

Yep