mot emission fail

[mp soulman]

took t25 1.9 dg watercooled for mot and failed on hydrocarbons. should be under 1200ppm mine was 1800ppm. i have tried altering mixture on carb but does not seem to make any difference. i have just got the van and its my first dg watercooled so after some tips/ ideas of good set up, possible carb replacement. when you rev the engine high it stutters a bit and exhaust pops when revs slow down and fumes are grim but it passed mot on co2, any advice much appreciated

[Aidan]

try wrapping the hose from the manifold that provides the vacuum for the servo in gaffer tape, this often becomes porous and allows air ingress so that 3 and 4 are running lean even though you adjust co to be right - if it's this you just need to replace the pipe with one that hasn't got the metal wire reinforcement that rusts

[toomanytoys]

A bloomin good service and tune up would be a good place to start
and a carb rebuild would work wonders too...

Can you fill out your profile a bit with location so we can suggest anyone near you to assist..

[kevtherev]

High HC is either unburnt fuel
or
Oil
or
both

[CovKid]

Last year mine (1.9 petrol) was:

C0: 0.26% (MOT limit 4.50%)
HC: 150 ppm vol (MOT limit 1200 ppm)

If you can't get it down with weakening mixture or a good service, you'll need to dig deeper. Your choke is fully off I take it.

[kevtherev]

Last year mine (1.9 petrol) was:

C0: 0.26% (MOT limit 4.50%)
HC: 150 ppm vol (MOT limit 1200 ppm)

If you can't get it down with weakening mixture or a good service, you'll need to dig deeper. Your choke is fully off I take it.

What should you be aiming for on emissions Covkid?
Not the MOT limits .. but the 1.9 WBX average readings.
From CO, CO2, O2, HC,

[toomanytoys]

My slightly tired 1.9 DG did 0.35% and 148ppm... I gave it a jolly good service and blast up the bypass before it went in...

1800ppm is a lot... Maybe it wasnt warmed up, old oil, choke not coming off properly... poor timing, tired plugs, blocked crankcase breather... all these items will add up..

[mp soulman]

thanks guys some really useful info, i suspect choke playing up so will remove carb and have look, and service and tune up

[CovKid]

Lot depends on age of engine to be honest but a reasonably youthful one should be able to make the figures quoted or slightly above. With most of these v-dubs, unless you have something fancy, you warm engine up, back off mixture screw until revs falter then turn back the other way until they return to normal plus half a turn. Under normal circumstances you should be well under the MOT requirements unless something else is contributing.

[fullsunian]

try wrapping the hose from the manifold that provides the vacuum for the servo in gaffer tape, this often becomes porous and allows air ingress so that 3 and 4 are running lean even though you adjust co to be right - if it's this you just need to replace the pipe with one that hasn't got the metal wire reinforcement that rusts

I would bet it is an air leak, just like Aidan says. I had another members (brickinit) van in for a test and it was doing exactly the same, turned out to be the rubber vac pipe for the servo had gone porous....An easy fix too far better than pulling carbs to bits
IAN