Terraclean findings

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Joined: Mon 10 Feb, 2014 16:37
Posts: 89

  Z3 roadster 2.0

Terraclean findings

Post by ualla » Tue 07 Oct, 2014 20:25

Hi all,

For anyone interested, I just wanted to provide my feedback on the Terraclean service.

On the 21st May (@73750 miles) I carried out a Terraclean (in South London) and was quite surprised with the results:

Before Terraclean:
CO = 0.41%
CO2 = 14.17%
HC = 108ppm
O2 = 0.65%

After Terraclean:
CO = 0.00%
CO2 = 8.61%
HC = 9ppm
O2 = 15.10%

This morning I took my Z3 for its MOT (@74641 miles) and asked for the emissions test printout:
MOT values:
CO fast idle = 0.14%
CO low idle = 0.25%
HC = 49ppm

Legal Limits:
CO fast idle = 0.20%
CO low idle = 0.30%
HC = 200ppm

Just thought I'd share my findings :)
Last edited by ualla on Tue 07 Oct, 2014 22:17, edited 3 times in total.

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Joined: Fri 20 Apr, 2012 09:11
Posts: 122

  Z3 roadster 3.0i

Re: Terraclean findings

Post by akirk » Tue 07 Oct, 2014 21:58

not sure I fully understand the significance of the figures - but they seem to be impressively low after the service, but then back up quite a way at the MOT
So, c. 5 months - does this mean that it is only of short term benefit - i.e. by next year will you be bak to the same?

What difference does it seem to have made to the feel of the car?


Joined: Mon 10 Feb, 2014 16:37
Posts: 89

  Z3 roadster 2.0

Re: Terraclean findings

Post by ualla » Tue 07 Oct, 2014 22:07

Good point, I'll amend the original post to include the legal limits as well.

Right after doing the Terraclean, the car did feel slightly better, but I don't know how much of that was thanks to the placebo effect.

When I got the Terraclean done, I asked how long it would last and I was told that in Canada they recommend doing this every 2 years. I'm sure the results also depend on external factors (fuel used etc). Also consider that in the last 5 months I have done only 1000 miles.

I personally expected the values to be lower.

Joined: Wed 24 Oct, 2012 14:34
Posts: 431

  Z4 coupe 3.0si
Location: Woore, Near Nantwich, Cheshire

Re: Terraclean findings

Post by TR4man » Tue 07 Oct, 2014 22:19

What on earth is "Terraclean"?

Joined: Mon 10 Feb, 2014 16:37
Posts: 89

  Z3 roadster 2.0

Re: Terraclean findings

Post by ualla » Tue 07 Oct, 2014 22:22

They basically unplug your fuel system from the engine and plug in their own external fuel pump. They run the engine for an hour on highly refined fuel to clean the engine, injectors etc and removes carbon deposits that build up over time.

It surely makes an immediate difference, but I have always been curious about the long term effects.

Website can be found here for more accurate information: http://www.terraclean.co.uk/

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Robert T
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Joined: Mon 12 Jun, 2006 11:35
Posts: 10046

  Z3 roadster 1.9
Location: Cheshire

Re: Terraclean findings

Post by Robert T » Tue 07 Oct, 2014 23:10

The after figures look somewhat suspect to me - for there to be 15% oxygen left in the exhaust, you are either running very very lean or the engine is not being tested at the same RPM as the first test. The figures from you MOT look more realistic and I would have been prepared to believe them as the after figures - they show a definite improvement. Have you noticed any improvement in fuel economy?

Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc

Joined: Mon 10 Feb, 2014 16:37
Posts: 89

  Z3 roadster 2.0

Re: Terraclean findings

Post by ualla » Tue 07 Oct, 2014 23:17

That is a definite possibility. I wasn't there for the actual test.

Another very suspect value was the lambda which went from 1.02 before to 2.2 after the terraclean. Shortly after I did have to change the vanos seals as the car had a lumpy idle. Not sure whether it was related.

Not really, fuel economy has been pretty much the same...

Joined: Wed 26 Feb, 2014 10:07
Posts: 133

  M roadster S50

Re: Terraclean findings

Post by Sailorbaz » Wed 08 Oct, 2014 23:34

I must dig out my recent MOT, 1st ever MOT on the car since we bought it in 2000 and never put it on the road . I remember looking at the figures from the test centre and thinking they were unbelievably low, maybe not right enough for a car only done 4500 miles.

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