no power below 2000rpm, bad MPG!

i would log boost requested vs actual with vag com and see what its doing. if youve replaced the MAF then this should rule it out but its worth while logging that also.

Yes it does have a N75, on the back firewall, two valves one is the N18 EGR Control Valve, the other the N75. Most places wont stock these, you used to be able to get them from vag parts at a good price but they have gone now so your looking at a local dealer for the part really.

But my initial thoughts are a vacuum pipe which is the problem, i had the same sort of issue with my car once where after a service the vacuum pipe to the vacuum reservoir bulb had come off, reconnected it and it was back to normal. So check all your small vac pipes and connections.

your lucky its not going into limp mode with over boost if it stays above loads like you said.

Anyway, yeah drop the turbo off and clean it up, from what i have read it will need to be manifold off though.

I'm thinking the vanes might be clogged - how much mileage has it done and how do you generally drive it, looking at your quoted mpg ....... it must be driven quite gently to get that. Have you tried giving it a good run through the gears a few times?

martincloud9 said:

Ok, the car has done 115000 miles. It has had regular services with the correct oil. By regular I mean either 6 months or 6000 miles. It has had to have the cylinder head replaced because the cam wore through a tappet.

What appears to have happened here. The EGR valve clogged up because of it coming on loads whilst 'town' driving. It also clogged up because there is oil coming from the breather pipe, not lots, but enough to turn the soot (from the EGR) in to sludge. I'm guessing that is what was making the glow plugs to keep failing...?
Somewhere along this line (probably the MAF sensor must have ballsed up) as the turbo started over boosting.

The MPG is back up to scratch. The turbo is settled back to normal, although it would be better if it started coming in to effect a little earlier.

Is there any way to get the turbo starting earlier? I.e. getting the veins aligned with a little more trim?

Click to expand...

Remap? Is it all running ok now? To be honest i'd consider giving it one good run a week .... mine gets a good run every day and the EGR is almost clean inside!

what eventually sorted the smoke on startup and no power below 2k?

martincloud9 wrote

What appears to have happened here. The EGR valve clogged up because of it coming on loads whilst 'town' driving. It also clogged up because there is oil coming from the breather pipe, not lots, but enough to turn the soot (from the EGR) in to sludge. I'm guessing that is what was making the glow plugs to keep failing...?

The EGR valve is prone to clog, and the inlet manifold to coke up too, because the hot sooty exhaust gas from the EGR meets the oily inlet charge (oil mist from the crankcase breather is normal) to form a nasty sludge which bakes on and slowly gets thicker.

Eventually the EGR valve starts to stick becuase of the buildup of crud. The low-rev issue could be from the valve never closing properly, letting some boost out. Overboost at the top end is again likely due to the valve not shutting properly, only now the exhaust pressure is higher thant the inlet and give overboost.

I doubt it has anything to do with the glowplugs, which are in the cylinders.

I guess you've cleaned the EGR valve up which has cured your problem (you don't say what you actually did). I hope you cleaned out the inlet manifold as well, as it will have been choked by the buildup of crud.



Somewhere along this line (probably the MAF sensor must have ballsed up) as the turbo started over boosting.

More likely stuck EGR

The MPG is back up to scratch. The turbo is settled back to normal, although it would be better if it started coming in to effect a little earlier.

Earlier than what? Below, say, 1700 rpm there isn't enough exhaust gas to spin the turbo fast enough to give full boost, even with the variable geometry turbine inlet vanes.

Is there any way to get the turbo starting earlier? I.e. getting the veins aligned with a little more trim?

At low revs the vanes are at minimum opening. This gives maximum back pressure, but crucially gets the gas speed up (smaller turbo inlet = faster gas flow) and it is the speed of the gas that is critical in getting the turbo spun up.

Trying to extend this lower in the rev band doesn't pay back as there isn't enough boost available to counter the rise in back pressure.

It is almost caused by curropted vac lines and hoses. Dont waste your time. Check them first of all. It is the cheapest method.

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Mate this was 5 years ago lol the dates at the top left of the thread lol

Haha

Sent from my HTC One_M8 using Tapatalk

Is it a problem for answering a subject which is almost actual also today...

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Well yeh, because people don't search for answers they starts a new thread, happens all the time, don't worry we have all done it when just searching through the forum

For example I suffered from my 2003 toledo 1.9 ASV engine and when I searched this forum i benefit from some subjects and get the solution

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