VW Golf MK4 Sudden power loss

Hello everyone . First of all, i'm happy to be a (small) part of the TDIClub community .

Unfortunately, after hours and hours spent on searching the web for people with similar problems as mine i kind of failed and decided to finally ask for help myself, a thing i don't really do that often because the internet is full of helpful forums..unfortunately not this time.

So the problem started a few days ago, when i went for a ride in my tdi(vw golf mk4 115hp, 6speed, ~380.000km) and first gear seemed fine, 2nd started accelerating pretty slow and then 3rd was really slow at accelerating, no matter how i had my foot on the pedal. I managed to get to 4th where it was a nightmare and was barely going up in revs and speed. At return from my journey i wanted to see what speed i could get up to and i barely reached 130km/h and that was really hard to do ! Mind you, my golf is a 6-speed one and in the past i have had no problems getting to higher speeds. I'm no mechanic, so i have asked around and people pointed me to the turbo and said that it might be broken. I've asked not one, but two people to drive behind me and see if i have smoke coming out of my exhaust..and nothing ! Not even when idling, reving at idle, 3rd or 4th, no smoke. So then i started looking myself at other possibilities and i saw something about the MAF sensor. I have tried disconnecting that and i don't know if it is my imagination or what, but the first time i go into 1st,2nd and then 3rd it seems to accelerate as normal but when i slow down and start again, it seems to be slow again. Also, in the past, when changing gears i could hear the "shush" (turbo spool/blow off or whatever it is called), but now i can't hear nothing anymore.

Any of you have any idea what could it be ? I'm really afraid of it being the turbo..because it cost hell of a lot of money so i'm trying everything i can do.


Sorry for the long post and i'm sorry if my question doesn't fit here..

Probable limp mode. The definitive check list is by Canadian_Grizzly.

You need to check for error codes. Do you have access to VCDS?

Is this a PD?

JB05 said:

Is this a PD?

Click to expand...

115HP; most likely.

my PD BEW golf did this with no code initially. just lost power, I reseated the connector on the turbo and it fixed it. not sure if it is like that for yours but it was really weak and slow but not actually in true limp mode if that makes sense.

another BEW that I had bought had a bad tandem pump, it would not rev up well in neutral would hang at 4300 rpm or so completely floored at idle. I checked and changed everything to find out the tandem pump was the cause.

only other thought would be something iinner turbo related and this also could be very likely if it revs good at idle and connector reseat does nothing. you might try working the actuator and seeing how sticky it 'feels' maybe needs cleaning possibly failing period. some good how to videos on cleaning it and I am sure this site could point you right if you needed help.


one other thing I am seeing right now on my BEW is it started losing power one day and set a few EGR codes. I cleaned the valve no joy. still kept losing power and setting limp mode under higher boost demand.

I checked cleaned turbo nothing. I unplugged the egr valve connector, drove it and it was fine or way better at least. drove it like that for a few weeks with it on my to do list when I got time but it is currently my Daily for a long commute and it started to whistle. noticed it is losing boost through the egr cooler somewhere so that is probably why initially unplugging that thing helped even though I could not hear it at that time.


maybe one of those thing will point you towards something, those have all been noted issues I have seen on bew in relation to low power and no smoke. in none of those except for the last one when the EGR would FINALLY trip to complete limp mode did I have any visible smoke.


first suggestion higher up is the best one though, if you have codes have them read, preferably by someone with vagcom but at least report if you have codes.


if you don't try looking at fueling issues as a first. that one I messed with bad fuel tandem pump would not set a code but it drove like it had a Smart 42 engine in it instead of diesel

Thanks for the replies ! Ok, so, i've been in vacation for a few days and in this time i had my brother go make a test for codes. He told me that it gave a code for a thing that is sometimes happening, in which i put the key in and the "immobilize vehicle" warning light comes on and flashes, but if i remove it and put it back in it all works..so i knew about that. This guy said to my brother that i'd have to change the turbo. Thing is, my brother didn't note the codes and so after i came back, i went and made the test myself and surpise, no error codes. Only thing that was apparent is that the vacuum gauge was not moving at all but when we tried it on a vw passat that we had nearby the gauge worked. This guy told me to buy a new vacuum pump but i'm holding back a little because i don't see to have problems with the brakes and i've heard that these things don't break that easily..
Also, the guy i went to with the VCDS said the rpms seem a little high. they are shy of 1k. i don't actually know what would be the normal rpm for idling.

@flee doesn't really "check all the boxes" for limp mode.. it doesn't feel like it.
@jokila No codes when i checked it myself. only thing is the vacuum gauge that isn't indicating nothing.
@speedy223 thanks for your suggestions ! i'll try them in the next few days when i'll have some spare time

If you have a vacuum leak the turbo will not act right.

I would rundown the vacuum and ensure it's good first.

I would generally replace the lines.

Curious where you are checking to see if you have vacuum, because the N75 controls the boost.

eddieleephd said:

If you have a vacuum leak the turbo will not act right.

I would rundown the vacuum and ensure it's good first.

I would generally replace the lines.

Curious where you are checking to see if you have vacuum, because the N75 controls the boost.

Click to expand...

Could i check for a vacuum leak myself? If yes, what could an easy way to do it ? I don't really have special tooling or things like that.

As for where i was checking the vacuum, it was the guy with the VCDS that told me the gauge wasn't even moving. (Or moving very very slightly, something along these lines.).