T 5 2.5 diesel sudden power loss .

[Sunny43.5]

I am not sure what has happened here but son was driving wifes old T5 2004 2.5 Turbo auto , anyway he drove home last night from uni no problems , Jumps in to go to shops this am and the van will not get past around 30kmh , I had noticed that since the auto was rebuilt late last year it had been a bit slow off the mark as the transmission place spent a fair bit of time with ecu settings to match the new rebuilt auto . Wondering what it may be as it just decided to happen over night , in neutral it seems to rev up to 3000 rpm okay but in gear not happening when we take off it changes gear and then just seems to run out of steam . I would add that just before the auto rebuild last year Highway Vtrouble had the van for a full service and when I picked it up they told me the Turbo was leaking oil internally and said it may lead to slow turbo kick in or has it failed now . It was never a problem before or after they serviced it only after the auto rebuild . I am just making sure that everyone has the full story to make it easy for suggestions . Howard PS yes have turned it off and on in case of limp mode kicking in .

[Sunny43.5]

No it seemes to be non boosting its slow off the mark then a small surge followed by slowing again if its on a hill it just almost comes to a stop . This is when I put on my dunces cap whats the MAF ?

[Rebuild]

Mass Air Flow sensor

http://en.wikipedia.org/wiki/Mass_air_flow_sensor

The small apparatus on the intake just after the airbox(on 2.5's), 4 or 5 wire plug on it.
If it is faulty or disconnected the car runs excessively rich, as the ECU defaults to safe settings.I disconnected mine once to see if it was still working and it runs but has no power much above idle.Makes more smoke also.


You can try disconnecting it, plug is tricky to release,and see if it runs the same.Likely dead/faulty MAF.If it's different or worse,means MAF is working and MAF may be ok.
You can also try cleaning the sensor with white spirit or similar.If you run an oiled filter instead of paper, it supposedly clogs the MAF up
Scan for codes if you can also.

Maybe check the impellor on the turbo too, see if it still freewheels??

[Sunny43.5]

Thanks so far guys is there any way to test the turbo or should I check the MAF first there are no engine light faults showing on the cluster , I know a guy with a laptop and VW programs so I will give him a call and see what turns up luckily its a spare van at the moment as my son still has his T4 the T5 is due to be sold soon .

[Rebuild]

Good idea to get it code checked if poss.
May give a proper idea where to start

I think the inlet to the turbo is reasonably accessible, by taking the intake piping off, low down on the driver's side to the rear of the motor.You should then be able to wiggle the impellor.
I checked mine by removing the exhaust side pipework.
5mm allen key and a few bolts(13 and 15mm IIRC) for that.There is a flex connection, so you can push the exhaust pipework out of the way a little.I found it easier to remove the whole lot.It's a little awkward to line everything up again to refit

[Sunny43.5]

Thanks Steve I have sent a request to the guy I know so I will wait for his diagnosis but thanks for the photo it will help if it comes to the checking of the Turbo . The impression I get is like it has gone into "Limp Mode " and is staying there , I remember not long after we got the van I was decending Cunninghams Gap here in Qld rainy night and lots of semis crawling down the range , I flicked over to manual mode to keep the van at a safe speed but when we cleared the semis I forgot it was still in manual probably 3 rd gear and took off I then realised it was revving high and quickly flicked it back to auto seemed okay while still going down hill but was bloody hopeless on the flat took forever to get up to any decent speed . VW don,t tell you that you only have to turn it off and on and it clears the limp mode , drove for another 30 odd kays before I thought I would switch it off and see what would happen . Well you can imagine our relief when it recovered .

[vdubmotorworx]

very very strange not to have either the gear display flashing or epc/glowplug light on the dash for this fault.. the only time you get big issues like this with no lights is something the computer cant see like fuel contamination etc..... if you use tiptronic to get up the gears slowly can you get it past 30kph? also put your foot on the brake..put in D and give it some revs..can you hear the turbo boost up and the release of pressue when coming back off the accelerator? disconnect the airmass meter and try with it unplugged. usually if the airmass meter has gone it will be 50% better when disconnected.??.. if yours has a DPF it might have broken up blocking exhaust gas flow..seen a few now...PM got.. try these mate and let me know...VDUB...

[Sunny43.5]

Thanks for the ideas Vdubmotorworxs I have tomorrow off so I will give ot the once over , thanks for the help so far guys .

[Cousin]

If you haven't already done so, Sunny, check the large air hoses
I had a clip fall off one a few years back, same problem as you describe
Pulled over, had a peak under the hood, found the disconnected hoses, fitted them back and all was good again

M

[Rebuild]

disconnect the airmass meter and try with it unplugged. usually if the airmass meter has gone it will be 50% better when disconnected.

??
don't you mean 50% worse

[vdubmotorworx]

??
don't you mean 50% worse

No... Better. If the airmass meter has failed then it puts a crappy reading to the ECU , if its disconnected the ECU has NO signal at all so it decides to use a average reading and use that. A average reading is better than a very poor reading, so it drives better disconnected...VDUB...

[Sunny43.5]

Thanks Rebuild for your idea that one has been checked as we had the dreaded intercooler hose clip failure years ago and because VW wanted some ridiculous amout of money to solve a circlip problem I beat them at their own game and just fitted 3 screws to hold the hose to the alloy body works a treat . So I will do some checking tomorrow based on advise given so far .

[Sunny43.5]

SUCCESS its fixed !! Okay what was it you ask well simple small things can kill an engine , I checked MAF looked all fine [out of interest with MAF disconected it was 50% worse would not get up hill near home] any way I was about to give up when I found a tiny vacuum hose from the brake vacuum line laying loose in the engine bay . It took me quite a while to find out where it had come from as it turned out without pointing fingers at HighwayV trouble where it was last serviced someone had redirected the main vacuum line in front of the oil filler cap instead of behind it this had placed the flexy hose to the vacuum resovouir under tension this caused the small connector to snap of right on the non return valve . Because of where it was placed it was not at first noticed so I luckily had a spare valve from an old T4 engine in the driveway fitted it and reconnected the hose and success all fixed WHEW This photo shows where it was located and the second where it should have been [IMG][/IMG]

[Rebuild]

IIRC the vacuum lines are partly involved with controlling the turbo vanes, amongst other things.With a line open to atmos, probably not getting any boost.

[vdubmotorworx]

great news mate.... easy fix...VDUB...