1.9tdi 110 SX Power Loss Problem

[Culli]

53 plate Leon 1.9tdi 110 SX

I suffered a strange loss of power a few weeks ago whilst over taking a slow moving lorry. In 3rd gear as the revs built up the engine suddenly seemed to die. It would then struggle to get over 2500rpm whilst in gear, although it would rev normally in neutral. Upon restaring the engine the problem was gone and the car drove as normal.
I was told not to worry about it unless it happened again.
Last night it did happen again. In 3rd gear it suddenly dropped power and refused to get over 2500rpm in any gear. I drove it for a while with the problem and although sluggish it would drive well. Once again after restarting the engine the problem was gone and i failed to be able to reproduce the problem. It feels like its a problem with the turbo as it usually kicks in around 2000rpm and it below that rev range the engine seems no different.

Any help is much appreciated.

 

[1.9...stefan]

sounds like its going into limp mode, have you got any mods on the car, really need to getit on vag com

 

[Culli]

the car has no mods. what exactly is vag com?

edit * i dont have any error messages appearing so not sure how vag com would help.

 

[Muttley]

VAG-com is a type of diagnostic software that you can purchase and run on a laptop, provided you have the right connection lead - it has a dongle in it, and is relatively expensive. There is a section of the forum devoted to VAG-com. Using it, you can find out what the fault codes are that have caused dashboard lights to come on, and can make some modifications to the stored parameters - for instance, closing down the EGR system to minimum activity, programming the doors to lock as you drive away, etc.

Limp mode is a protection mechanism built into the ECU. If it detects some readings from the engine that are outside its preset limits, it goes to a more conservative map, reducing the amount of power available to avoid damage to the engine.

It sounds like you are hitting limp mode. How many miles has the car done, and has much of it been slow-speed, shopping trips or in-town commuting? There are two faults I know of that are likely to cause the symptoms you're seeing.

The one that gets reported most on here is sticky vanes in the turbo - soot builds up and causes the turbo's variable geometry inlet blades to stick in the "closed" position, the one that is used at low engine speeds to increase the gas flow velocity through the turbo and get it spinning earlier to provide boost from low revs. If the vanes stick, then as revs rise the turbo tries to overspeed, raising the boost and triggering an inlet manifold overpressure fault. This drops you into limp mode, to keep the revs down. Limp mode is reset when you switch off the engine (well, most limp modes).

The other one is sticky EGR valves. The exhaust gas (hot, sooty) added to the inlet (yuck) for emission control purposes (yes, really!) combines with oil from the crankcase breather (plumbed into the inlet upstream of the turbo) to form a sticky sludge that bakes onto the hot inlet manifold, choking it and eventually causing the EGR valve to stick partly open (it's supposed to close at higher revs). This allows too much exhaust pressure into the inlet manifold which again results in an overpressure reading and limp mode.

The EGR fault is usually seen on higher-mileage engines - it happened to me on an Ibiza at 80K. The sticky vanes can occur at relatively low mileages.

 

[Culli]

the car has just passed 50,000 miles. when originally bought i lived about 60 minutes from work which included several bypass roads where i could open her up. about a year ago i moved about 5 minutes from my work and the car rarely hits the higher revs. i do the occasional longer motorway journey traveling to and from basketball games, but maybe not enough. so i presume the problem is the first one you mentioned. how would i go about getting this fixed? is it something which will clear on its own? or do i need to repair/replace parts. it has only happened the twice and i have run the car upto the rev limiter in 2nd and third and not been able to reproduce so does that mean its not a big problem or the start of a problem.

please excuse my lack of knowledge of car parts etc.

 

[Robb1990]

You need to clean the turbo out. There are 3 ways to do it really, either take the whole thing off, strip it, clean it and build it back up and replace. Use a cleaning product which will involve taking off the axhaust and spraying in a cleaner. The third option is to give it a good old ragging. Get the engine warm, then run through all the gears to around 4000Rpm, obviously keeping to the speed limit Do that and it should see you clearing out the turbo, if its only just started doing it, then the soot shoudlnt be too baked on yet and fairly easy to clear.

4th and 5th gear work the tubo hardest, full throttle from around 2000Rpm

Id try the driving hard option first obviously. then if the problem still persists and is annoying you, go for the other 2 options. the strip down wont be cheap though, so be warned now

If its any help mine is doing the same thing, if i go on the dual carrigeway near me, cain it in 3rd to 4000rpm, shift to 4th keeping the revs high, then 5th, it helps ALOT, if i then go a week or so without doing this, it'll be back into limp driving normally (ie shifting at around 2Krmp, then planting it in 4th when on bigger stretches of road) So key is - once its hot, rev the balls off the *******, it'll love you for it

 

[Muttley]

It does sound like sooted-up turbo vanes. One way to fix this is to burn the soot off, by getting the turbo hot and keeping it hot for several minutes. This will happen when the engine is loaded at mid-high rpm. Ideally you need to find the longest continuous hill on a motorway or dual carriageway near you and hold your speed as high as you can (keeping legal limits and traffic conditions in mind) while climbing the hill. Some have reported seeing sparks behind them (in their mirror, obviously) which is the smouldering soot being ejected. However, you aren't looking for fireworks, just to burn the soot off the turbine section of the turbocharger, the bit that is in the exhaust flow.

http://www.kadekticaret.com/whatisaturbocharger.htm
http://forum.ih8mud.com/80-series-tech/132674-turbo-faq-info.html
http://www.motortrend.com/roadtests/coupes/112_0606_2007_porsche_997_photos/photo_17.html
http://www.motortrend.com/roadtests/coupes/112_0606_2007_porsche_997_photos/photo_18.html

Turbo stripdown and cleaning pictures here, including an animation of the vanes.

 

[MBG1]

I have had the same "sticky vane" issue with my Turbo, displaying exactly the same fault i.e. power drop off and limp mode. I rarely get chance to exceed 2000rpm. My local mechanic (an ex Seat Master Technician) advised me to try a double dose of Millers Diesel Treatment initially then as recommended and then take it somewhere and thrash it through the gears. I did that 3 weeks ago and the results have been excellent, smoother performance and a general feel of more power. I now make sure i give it some hard acceleration at least once a week and so far so good. Fuel economy is good (56mpg average)
Must have saved me hundreds of pounds in reconditioning costs. And NO i don't work for Millers I am just a happy customer.