Exhaust gas leak. Suspect manifold

[DamirGTI 323]

As said , high HC exhaust content can often be blamed on ignition system/timing , as the most common fault for high HC emission .. but also the vacuum leaks , incorrect AFR ( as the AFR weakens the HC emission increases , cause of lean misfire ) and worn out engine mechanically .

 

Guess it needs re-mapping again , but making sure all the inlet tract and exhaust is sealed before mapping .. and maybe turning on the MAP sensing option if it's there why not to use it ?

 

Also , i'd maybe try to perform an leak down test .. just to be sure that the engine is good mechanically .

 

Combustion chamber design - did you maybe by accident turned the pistons towards the distributor rather than the timing belt side ? as this will reverse the squish areas on the piston crown - combustion chamber , which will mess up the mixture burn rate and made the engine more prone to high speed detonation/pre-ignition , thus having out of spec. exhaust emission too .

 

D

Edited September 13, 2019 by DamirGTI

[Telf 222 2 Cars]

1 minute ago, DamirGTI said:

Combustion chamber design - did you maybe by accident turned the pistons towards the distributor rather than the timing belt side ?

No mate definitely not

[jackherer 543]

What is a normal HC value in PPM for a 205 GTI?

 

I just looked at some of my old MOTs and it passed with 587 ppm in 2016 and 603 ppm in 2018.

 

Both are HIGHER than yours!

[Telf 222 2 Cars]

Kieran,

 

The second chart is how it is right now . I haven't touched it other than open the bleed screw. I imagine it will probably idle ok atm

[jackherer 543]

It's hard to make sense of this when you said in your text earlier that it "massively failed the MOT on hydrocarbons" but both of those charts are passes on HCs.

[jackherer 543]

Your fuel smell must be coming from somewhere else like a hose or something, those HC values on both charts are less than my 205.

[Telf 222 2 Cars]

Mate tbh it doesn't matter about the values. The fact is that ever body who goes near the car without prior knowledge and takes it for a drive wants to get out 5 minutes later due to the stink of fuel/exhaust whatever so something is clearly wrong. I just don't understand what. My missus won't go near it. Your mum told.us to turn it off last month because it was stinking the house down. Both garages today everybody was like 'jesus Christ!' and even the lotus place commented as soon as I pulled up

[Telf 222 2 Cars]

The MOT tester said it was a fail. I subsequently checked the figure (actually about 10 minutes ago) and read the 1200 ppm. 

So yes that was factually incorrect bit that's what they told.me at the test station.  Everywhere I've been today I haven't commented on the car - I've asked them to check it out for themselves. Not said a word and they all have driven it and bought it back with the same thought. It's been up on a lift and checked. No fuel leaks apparent . No blows other than a small hole between the center and rear box at the bracket. 

 

 

[jackherer 543]

There is obviously something going on and I'm curious what it is but I just want to get the facts straight.

 

If you say the HCs are off the charts and they aren't it's impossible to apply logic to it.

 

 

[jackherer 543]

Can someone without an Emerald post their MOT test HC values please?

[Telf 222 2 Cars]

That's why I posted the figures so you could see. I dunno what's going on with it either. 

[jackherer 543]

Have you given any thought to the various fuel tank filler and breather hoses?

 

I don't know what all of the hoses on the fuel tank do and I seem to remember some confusion around them when we were assembling your car.

[DamirGTI 323]

There's few variates of the HC in the exhaust gasses .. some are nearly odourless while others are , well , smelly !

 

"Aliphatic HC" are almost odourless , while "Cyclic aromatic HC" (benzene , toluene etc.) are the ones which produce odour  .

 

D

[Telf 222 2 Cars]

I can check but I'm pretty sure it's assembled correctly . The workshop manual had a thorough going over after it was finished . Also it doesn't smell at all when it's stood. I mean it doesn't vent whilst it's on the drive. I went and checked the other day whilst the sun was out just incase 

 

The thought has occurred to me also

[Telf 222 2 Cars]

Damir - are the different emissions indicative of something eg a failure , pre ignition or something?

[Telf 222 2 Cars]

I also noticed today (as several different t people took it for a drive) that on initial pull off the exhaust was blowing either white smoke or mist as the car moved off after start/idle  

[jackherer 543]

So are all of these people that are noticing the smell detecting it predominantly inside while driving it?

[DamirGTI 323]

28 minutes ago, Telf said:

Damir - are the different emissions indicative of something eg a failure , pre ignition or something?

 

Not sure , but as we said any ignition "errors" so to speak will shift the emissions off creating incomplete combustion , which makes - unburned HC's and partially burned HC's  , and some other derivatives (hydrogen , soot etc.) .

 

 

D

 

[DamirGTI 323]

"My missus won't go near it. Your mum told.us to turn it off last month because it was stinking the house down. Both garages today everybody was like 'jesus Christ!' and even the lotus place commented as soon as I pulled up"

 

This sounds to me just like my recent "battle" with an Nissan , the exhaust emission was so bad that people reacted the same way - run away asap ! hurts the eyes as much as it does the nose/lungs .. just unbearable smell of something which cannot be described .

Eventually , after few months of trying out MAF sensors , lambda sensors , checking vacuum leaks , evap leaks , digging with the scanner etc. ... it was down to the worn out bottom end , precisely piston rings and only the oil control rings (and pretty severe cylinder wall glazing) .. compression was good measuring 14Bar @ all 4 cylinders .

 

D

Edited September 13, 2019 by DamirGTI

[AlexRS2782 136 1 Cars]

34 minutes ago, jackherer said:

Can someone without an Emerald post their MOT test HC values please?

These are the results from all the MOT's i've put mine through over the years - 1991 J Reg 1.9 GTI - standard management & no chips / remapping.

May 2019 - CO 0.881 HC 628

May 2018 - CO 0.690 HC 376

May 2017 - CO 1.094 HC 288

May 2016 - CO 0.375 HC 119

April 2015 - CO 0.996 HC 129

April 2014 - CO 0.990 HC 151

April 2013 - CO 2.540 HC 150

April 2012 - CO 1.530 HC 122

April 2011 - CO 2.680 HC 160

April 2010 - CO 0.890 HC 109

April 2009 - CO 0.840 HC 127

[Andy 105 1 Cars]

Love to see a post of your fuelling  and ignition map if you could post them. I have looked back at your photographs of your manifold. That and plugs suggest weak mixture to me . I take it you are using an o.e inlet manifold and modified the throttle to take a throttle pot. The afm is just a dummy to keep the o.e look and a coilpack running wasted spark. 

[Telf 222 2 Cars]

Andy - yes that's correct , it's built as you say. 

[Telf 222 2 Cars]

Damir . With regard to the bottom end the and build in general the crank was measured at a machine shop and found to be within normal limits. Shells were then sourced accordingly. The pistons are reused with new liners and piston rings. The top end is just standard bit shimmed as per the Haynes manual. 

 

I'm terms of the engine failing it seems to be making the correct power.it isn't using water, nor oil. There are no odd noises. It doesn't appear to have any signs of failure as far as I can tell.

[Telf 222 2 Cars]

I will get a compression tester fitted and see what results that gives over the weekend

[Telf 222 2 Cars]

Kieran. Yes they all say the same thing . Seems ok with the windows up but can smell it when moving/stationary with them open