After market boost pipes and smoke?

[BenO]

Hi all

I’m trying to get to the bottom of smoke issue that has developed as a result of installing aftermarket boost pipes, (SFS). The issue began after installing a full silicone set, and has now become worse after installing a set with alloy sections.

The car:
Cupra TDI, non mapped with a full straight through 2.5" exhaust. No fault codes, no vac or boost leak. EGR is standard, no noticeable drop in mpg...

The issue:
The car appears to be over fueling when driving in slow moving traffic below 1500 rpm such that i can see smoke when stationary and a lot of smoke when pulling away just on boost. If i sit stationary holding the revs at around the turbo spool up point i can create my own private smoke screen to hide in. This is embarrassing

Am i right in thinking that at these low revs I’m not getting enough air through to combust the amount of fuel that’s being injected?
Could the MAF be thinking that the volume of air coming in is fine, when in fact post MAF larger diameter boost pipes result in a lower than expected amount of air as boost pipe volume increases? Would a larger MAF unit compensate for this?

Any help much appreciated!

Cheers

 

[glynnd]

Colour of the smoke is?
Glynn

 

[BenO]

Smoke colour is light grey.

 

[rscott4563]

I'd be really interested in finding out the answer to this question too as firstly I'm considering getting the SFS alloy pipework and secondly because I had (sometimes still have) this grey smoke issue at low revs.

I first had the grey smoke issue when I fitted my TD hybrid turbo and it was down to the map not being setup properly so I was overfueling when the turbo wasn't pushing enough air due to it needing more time to spool up than a standard turbo.

Ryan

 

[BenO]

I'd be really interested in finding out the answer to this question too as firstly I'm considering getting the SFS alloy pipework and secondly because I had (sometimes still have) this grey smoke issue at low revs.

I first had the grey smoke issue when I fitted my TD hybrid turbo and it was down to the map not being setup properly so I was overfueling when the turbo wasn't pushing enough air due to it needing more time to spool up than a standard turbo.

Ryan

Hey mate, Im not sure what effect larger pipework has, (if it is larger?). I suppose increased pipe volume = decreased air velocity, perhaps too little air under normally aspirated conditions, I have no idea.
Im not blaming anything on the pipework, it may be complete coincidence that the issue started at the same time and probable that the pipework exentuated an existing issue. I doubt very much it has anything to do with sfs in particular. Besides it seems a good kit!

Im getting a new fuel pump fitted as mine is leaking so after this week i may have a culprit. The jury is still out on the health of my turbo.

It seems that grey smoke can mean a lot of things. Have you had a wiff of yours? Burning oil? Coolant going awol? Timing set up ok? dirty air filter? compression problems etc etc..

I'll let you know!

 

[jonjay]

Hey mate, Im not sure what effect larger pipework has, (if it is larger?). I suppose increased pipe volume = decreased air velocity, perhaps too little air under normally aspirated conditions, I have no idea.
Im not blaming anything on the pipework, it may be complete coincidence that the issue started at the same time and probable that the pipework exentuated an existing issue. I doubt very much it has anything to do with sfs in particular. Besides it seems a good kit!

You may be onto something here because all my grey smoking issues at low revs have really died down since my twin air feed.

 

[BenO]

Ok, its nothing to do with the fuel pump as its been changed and the issue is worse if anything. Although the car feels better than its ever felt and pulls like a train further into the rev range than ever, quite shocked by the increase in performance

Possible loss of oil so im monitoring the level and turbo behaviour / noise now. I wish something would just break and show itself. I'd like to change the turbo but its an expensive gamble.

If im looking at a foobar turbo seal does anyone know how i can prove it without taking the turbo off? Or is a loss of oil pretty self explanatory?

 

[TornadoRed]

I’m trying to get to the bottom of smoke issue that has developed as a result of installing aftermarket boost pipes, (SFS). The issue began after installing a full silicone set, and has now become worse after installing a set with alloy sections.

The car:
Cupra TDI, non mapped with a full straight through 2.5" exhaust.

You might need a custom remap to take full advantage of the new boost pipe and exhaust.

 

[BenO]

Think i,ve cracked it! The theory may be pants but if it works then

Working on the theory that the new boost pipes are great when the turbo is fully boosting, but result in a lack of air when off boost, (perhaps down to my current mods and no map, cheers TornadoRed), then i need to get more air through at these low revs. As the EGR opens more on idle and low revs i thought it probably wasn't helping with air availability and it coincides with the smoke production. As JonJay said, more airflow has resulted in less smoke.

So I clamped up the vac line today so the EGR remains closed and........ NO MORE SMOKE!


The CEL came on as expected but not a wiff of smoke even after sitting idling then pulling away.
Looks like i'll be blanking the EGR as soon as poss then. Would be interesting to see if any others with similar mods who have held off mapping their cars, have had any similar experiences.

Cheers all!

 

[jonjay]

Think i,ve cracked it! The theory may be pants but if it works then

Working on the theory that the new boost pipes are great when the turbo is fully boosting, but result in a lack of air when off boost, (perhaps down to my current mods and no map, cheers TornadoRed), then i need to get more air through at these low revs. As the EGR opens more on idle and low revs i thought it probably wasn't helping with air availability and it coincides with the smoke production. As JonJay said, more airflow has resulted in less smoke.

So I clamped up the vac line today so the EGR remains closed and........ NO MORE SMOKE!


The CEL came on as expected but not a wiff of smoke even after sitting idling then pulling away.
Looks like i'll be blanking the EGR as soon as poss then. Would be interesting to see if any others with similar mods who have held off mapping their cars, have had any similar experiences.

Cheers all!

OOOO

 

[glynnd]

You may be onto something here because all my grey smoking issues at low revs have really died down since my twin air feed.
Whats this look like then Jonjay?
Glynn

 

[jonjay]

Basically two feeds from fogs that joined by a T piece.

Probee has done this on his LCR.

 

[Husbandofstinky]

So I clamped up the vac line today so the EGR remains closed and........ NO MORE SMOKE!

The CEL came on as expected but not a wiff of smoke even after sitting idling then pulling away.
Looks like i'll be blanking the EGR as soon as poss then. Would be interesting to see if any others with similar mods who have held off mapping their cars, have had any similar experiences.

Cheers all!

I haven't blanked off the EGR yet and I'm experiencing very similar symptons as you are(or were). Basically over fueling just off boost and loads of grey smoke - looks terrible. These symptons did not appear after any changes though (a good six months after the last mod and map).

Going to have to give this one a try anyhow.

 

[jonjay]

This could simply be the injection timing as there is a lot more air going into the combustion chamber...