Split second power loss on Leon TDI 150

[BenO]

Hey all, wonder if someone could point me in the right direction as this is niggling at me now..
Been thinking it was just my imagination but its happened too many times for that now. I'll be driving along, usually at a constant motorway speed, on boost and all of a sudden it feels as though i've driven through a patch of treacle, as if for a split second the brakes have been lightly applied. The episodes only ever last for a split second and in different locations, (so it isn't me driving over the same spot of road!). There are no other symptoms that im aware of, just this weird feeling of power loss / braking.
What do you think? Turbo, timing or am i just a crazy person

Thanks

 

[Seat Adam]

Mine does the same thing. Wondering if the diesel filter needs changing. Also make sure the air pipe is on properly after the MAF sensor, that also causes that, but usually at a certain rev.

 

[BenO]

Ok thanks i'll give that a check, fingers crossed it's nothing more serious.

 

[S3 AKR]

I get this too. Not very often and normally 1st thing in the morning. I'm going to check my pipework first then if it still does it on Sunday, I'll sit back, have a cup of tea and a think! I wondered if it could be the MAF starting to play up and may even think about giving that a clean too.

Are you guys running similar mods to me at all ?

 

[BenO]

My only mod thus far is a Piper turbo back exhaust but i don't think thats to blame. If a pipe had blown off, or was about too, would the problem be this intermittent? I've been thinking about the turbo bearing, if that were on the way out could it run 'rough' every so often and influence boost? I work with impellor water pumps and when the bearings are starting to die its generally quite an intermittent vibration.. Im going to give it a good look over the weekend if this snow holds off. Cheers for the input buds...

 

[sssstew]

yep agreed with whats been said so far, would be good to do some logging with vag com if you can re-create the problem, see what the boost and fueling is doing at the time.

 

[S3 AKR]

checked all the pipework today and now suspect the MAF. Pipes were all OK but the TIP was coated inside with a very fine layer of oily residue which I assume has come from the air filter. Glad I did it too as I found a broken bracket above the alternator (the engine cover mounts onto it) that was digging into one of the water hoses really badly. Covered it for now whilst I hunt for the part on ETKA so i can replace it in the week.

 

[paddeh]

is the bracket the one that also hold the upper boost pipe?

bad design it is...

 

[ManOnTheMoor]

Mine has this - occasionally happens when lift off power, get a hiccup then normal service resumes - been meaning to look at it, last time it was fixed by dealer, trying to remember something about a blue clip/hose near turbo but not got copy of service print out to verify...was hoping to look this friday but snow may put pay to that

 

[glynnd]

checked all the pipework today and now suspect the MAF. Pipes were all OK but the TIP was coated inside with a very fine layer of oily residue which I assume has come from the air filter. Glad I did it too as I found a broken bracket above the alternator (the engine cover mounts onto it) that was digging into one of the water hoses really badly. Covered it for now whilst I hunt for the part on ETKA so i can replace it in the week.

That bracket breaking is a common problem, mine has now been welded 3 times!
Glynn

 

[S3 AKR]

ordered a new bracket....... oh and S3 vents......... erm...and an S3 lower strut brace.......... got ETKA then got carried away!

 

[benhampshire]

I had this exact problem and it did my tree in for about 3 weeks.

It was the clips had worn on the intercooler pipes at both side (bottom of the intercooler). Everytime i put my foot down there was a hesitation then it would fly but not as much as usual.

Turns out the clips had worn but were still gripping enough apart from full boost. Replaced them issue went away for 3 months.

Now as my latest thread shows the problem's back and i'm weeping oil from the joints on the ic quite badly and have a fair bit of a 'wooshing' noise.

Replacing pipes and clips this time.

 

[volvic]

Hey all, wonder if someone could point me in the right direction as this is niggling at me now..
Been thinking it was just my imagination but its happened too many times for that now. I'll be driving along, usually at a constant motorway speed, on boost and all of a sudden it feels as though i've driven through a patch of treacle, as if for a split second the brakes have been lightly applied. The episodes only ever last for a split second and in different locations, (so it isn't me driving over the same spot of road!). There are no other symptoms that im aware of, just this weird feeling of power loss / braking.
What do you think? Turbo, timing or am i just a crazy person

Thanks

had the exact same problem, turned out the fuel filter needed changing

been fine since

 

[Seat Adam]

I've still got to change my filter, mine still does it. May have a quick look under the car at work next week though as mine seems to make a loud whooshing under boost. Hopefully normal, sounds great! There is quite a bit of smoke under acceleration as well though, want to change the air filter too though as it is very black. No fault codes shown up for boost abnormalities.

 

[benhampshire]

Yeah i didn't have fault codes either, but if you have vag com look at the boost pressues, pressure request and actual. graph them and on mine you could see the hesitation car wanted a lot of boost and wasn't getting it.

It was quite easy to see over along distance of smooth driving with only light changesi.e in 6th little throttle then off and you could see the scale getting bigger.

As someone mentioned fuel filter is always a good one to check, black smoke means over fueling somewhere if its a lot. If the air filter is clogged as well this can be a cause... but i'd double check the pipework to be safe

 

[oldman]

mine does get this at times and thought it was normal.

How does one log in vag-com? as i have it but no clue on usage i'm afraid.
Is a fuel filter not changed as part of any service? otherwise etka and part searching is my weekend of fun!

 

[benhampshire]

mine does get this at times and thought it was normal.

How does one log in vag-com? as i have it but no clue on usage i'm afraid.
Is a fuel filter not changed as part of any service? otherwise etka and part searching is my weekend of fun!

Fuel filter should be changed at the garage but it can get clogged depending on fuel quality etc how much bio diesel is in it etc (think as part of the enviro push diesel has to be up 5% bio or something - sure somebody will correct me)

Logging into vag com you need a cable either the official one quite expensive or one off ebay - cheaper but less reliable and functionality but like 10% of the price of the official one.

Once you are setup you have controllers to see different parts of you car, engine, electronics, abs etc.

In each one you have have measuring blocks, if you go into engine, then select measuring blocks it think its in the range between 008 - 011 boost pressure request/actual boost pressure.

Different for each car/software version... but this gives you a good idea: http://www.ross-tech.com/vag-com/tour/m-blocks.html

You can then save the data to a .csv file and import into excel or open office and plot a graph from the data you collected (easier to see than live readings at times)

I'm sure some the guys on here will other advice and suggestions.

 

[BenO]

had the exact same problem, turned out the fuel filter needed changing

been fine since

Cool, got a service coming up so il get it changed, cheers mate. I have the cheapy version of vag com so i too am going to learn how to use it. Its all gobledegoop to me at the moment.

 

[oldman]

cheers ben,
will look at doing this and see what it shows.
will def get that done at next service as well then.

cheers all and sorry if hijacked a little scrunch

 

[BenO]

Just an update on this little problem, had the fuel filter changed as part of a service and it hasn,t happened since, Horray! Cheers for the pointers.