Golf TDI loses power at 2500rpm

[kleky]

Recently bought an '02 Golf TDI PD 100 SE passed the mot no problem but have found when I accellerate there's plenty of power until it reaches about 2500 rpm then the power diminishes, and stays that way with poor power for the rest of my journey until I stop. Same on the motorway at 80 mph, same thing happens and the car won't go any faster and struggles to do 70 up an incline. When I stop and turn the ignition off, it seems to reset something and I have power there to accellerate up to the 2500 rpm again; if I keep at below 2500rpm the car seems to drive normally. Any ideas anybody, is it an electronic fault, or something else?

Further to this I've now found that it doesn't always have a power loss at 2500 rpm when accellerating from standing , seems more likely when in 3rd and 4th gears; still can't do much more than 80 mph though.

[A_John]

You describe a very sililar problem that I have with my VW! Mine is a 2001 (Y) golf TDI 115bhp SE (6 speed). The problem I have is as follows:
Up to 1800 rpm - no turbo
Between 1800 and 2300 - Turbo kicks in and power appears normal.
Above 2300 rpm, power suddenly falls away, therefore in 4th gear the car won't go faster than 60mph. I need to drop into 5th or 6th to go any faster, but then I struggle to reach 80mph on the flat. - obviously not right for a car which (according to VW) has a top speed of 120! This can be rather embarrasing when overtaking, particularly on hills - the other day I struggled to pass a lorry on an incline!
The problem has also affected fuel economy. When I first had the car, I would easily get 53 -55 mpg, now its nearer 45mpg.

This problem has been masifesting itself over a period of time, when I first had the car I'm sure I had more power than I have now. It is also more noticable when the engine is cold.

I've noticed the air mass meter mentioned a lot as a potential cause, could this be the problem with mine?

If anyone can advise on the problem I would be grateful. - i can then decide whether to repair the fault or get shot of the car!

[Chilly]

Hello,

I have a Passat 130 TDI when I first bought it would not go over 3000 revs. Replacing the air flow meter has fixed this problem. It was about £80 for the bit and 15 mins to fit. Unfortunately this has revealed another problem with the ERG valve, but that’s another story.

There are several posts about the air flow meter or MAF on this site it might be worth having a look.

Thanks.

[A_John]

It sounds like the Air flow meter then. I tried disconnecting it last night and it made little or no difference to performance, except at low revs, where there was some improvement. Still flat as a pancake at spped though.

I suppose at £80 quid or so it's worth trying.

One thinh though, according to the Bosch website, the part I have fitted to my car isn't listed as the one for my car! Does this make a big difference, and does this suggest that the MAF has been changed before (the car had done 60k before I bought it)?

I'll try speaking to VW and take their advice. Shall let you know how I get on.

Thanks for the info!

[kleky]

Thanks for the contributions to my problem, here's an update: I took my car in for a diognostic check at the local VW agent, cost me £30, they said the problem was the "waste gate" in the turbo was seized; if the pressure builds up excessively in the turbo, a pressure transduser cuts the amount of fuel being injected, this is what I was told by the garage technician.
I had a quote to rectify it ... just under £1000, and that includes a 10% discount, nearly £600 was for a new turbo; I declined the offer and decided to live with it for the time being while considering replacing the tubo myself, or getting mine repaired, the VW agent would only fit a new part.
As it happens I no longer have the problem, I gave the car a bit of a thraping in the lower gears and it seems to be ok now, amazingly! I assume the waste gate must have been blown free.
I don't think I would recommend this course of action for other similar problems, but I would say the diognostic check is worth it, rather than spending money on new parts that may not be required.
Good luck

[glynnd]

If you look in the passat forums you will see comments about the wastegate on the turbo sticking due to carbon build up. When it sticks shut you have great fun with the performance;)

[toledotourer]

Further to the info posted on the lack of power, I had the MAF replaced this week on my Seat Toledo 1.9 Tdi. It cost £20 for the diagnostic test, which actually didn't identify the problem, and £50 for the MAF. The difference is amazing and better than it's run for ages. Certainly worth trying as a first solution rather than the expense of other repairs. :D

[A_John]

Well I have since taken the cr to VW and £60 later came out with a new MAF. That was what the problem was. The car is not running much better, and it goes like a little rocket!

Having spoken to a few mechanics about MAF's they say its more or less a consumable item and should be replaced every 2 or 3 years.

Apparently the problem is a design flaw in the unit itself: What happens is that the electrical output on the MAF slowly deminishes over time, possibly caused my condensation on it after being left unused e.g. when parked overnight. Even though the sensor itself is encapsulated in plastic, microscopic amounts of water vapour get into the sensor, slowly reducing the ability or it to provide an output.

This explains why there is a suden loss of power - the MAF determines how much load the engine is under - by the amount of air being drawn in. When this fails, the ECU does't know how much fuel to inject and therefore defaults giving drastically reduced power. The turbo is probably working correctly, but because the ECU isn't injecting additional fuel, the effect of the turbo is reduced. This can also lead to reduced fuel economy as the engine is being wrongly compensated with fuel, which just goes out the exhaust unburnt.

In a nutshell:

Have a Turbo Diesel?
Have a loss of power?
Unsure why?

Buy a new MAF!!

[kleky]

Thanks for the info on the MAF, but I have already looked into the fault being related to that, and the conclusion was: because the loss of power is sudden and then continuous until being reset by switching the ignition off and on again, it's not the MAF and probably the turbo not shedding excessive pressure. What I haven't resolved yet is whether a new Turbo is required because the wastegate is internal, as the VW agent says, or whether there is no wastegate and some other mechanism can be freed. At the moment I'm living with the problem as I can now judge how far to take the engine, which has plenty of power up to the poinmt it loses it.
I'll try and fix it myself when I'm sure of what's needed.
Cheers for now
Steve

[seymourte]

Ok I'm new to this so bear with me. Recently bought my first Golf, a 52 plate tdi130 se estate with 37k & fsh. First 3 months fine no problems & very pleased with it. Towed caravan fine no problems on first trip. But just been away again towing caravan & on way thru Wales experienced power loss up steep hills. Felt like an sdi rather than tdi - turned engine off - re started car & appeared ok as per other messages. Same thing happened on return journey - & so far only manifests itself whilst towing. Have read other messages so have an idea where to start looking to trace problem, but my question is - shouldn't the car tell me something is wrong when this happens - car has on board computer which supposedly gives an indication of the cars status which it says is ok when clearly its not ?
Other problem I have is with boot lock doors all open ok but boot doesn't allways open fron the remote - either have to us switch on drivers door to release or use the key - does not prevent access just a little annoying - any ideas ?

[kleky]

Sounds like you've got the same problem as me, I now only rarely experience loss of power, usually on a fairly slow up hill climb at steady speed, seems to be ok when accellerating hard, which wasn't the case when I first had the car. I agree with you that the onboard computer should tell you what's failed, but it doesn't, you have to pay a VW agent to run a diognostic test at their premises, and then hope they don't try and rip you off. After my experience with VW, this is the first VW I've owned, and it'll be the last. Sorry, I can't help you with the door lock.
good luck

[cookie_monster]

Hi i was wondering if anyone has had the same problem as me...i have a Golf 1.9 SE TDI (90bhp).......iv had it a week now and it has no 'kick' in it at all.....the turbo does not kik in at any rev....my last 1.2 fiat punto had a better pick up with around 60 bhp!.....i went to the vw dealers they sed i shud have a diagnostic check on it which will cost me £50 but he goes it does not pick up all faults and we may not be able to tell you what is rong......i then went to a local garage where he pulled the electrics out of the MAF (basically disconnected the sensor) i think....i then took it around the block and it felt much faster and could feel the pick up .........im confused to what it could be?.....also if i drive around with the sensor out am i damaging the car in anyway?....does it effect the fuel consumption?....any suggestions with this problem would be of great help........
.....thnx in advance!

cookie_monster

[kleky]

Sounds like your another one coming up against the crap service offered by too many VW agents - they're making a fortune out of running diagnostic tests, even if they did find out what it is there's a good chance you'd be ripped off on the repair. Do I sound disallusioned with VW? yes I am.

[cookie_monster]

yeh.....the vw agent was like the £50 will only do the diagnostic.....after that i will charge u £80 an hour to look at the problem...i thort to myself....yeh u kno how to put a student in bigger debt dnt u.....
kleky..... did u sort ur problem out with the lack of power in ur car? ....if you did what was it?
cheers

[kleky]

I didn't sort the problem out fully, my problem is almost certainly something sticking in the turbo which now only does it every so often, so I'm putting up with it. My lack of power is restored when I switch the ignition off and back on again. It doesn't sound like you have the same problem and I would say it's likely to be the MAF (mass ait flow) transducer from what I've picked up on these forums,; it's a common fault with VW turbo deisels. they cost about £80 though, I'd see if you can borrow a working one to try, apparently it's an easy job to fit it. Hope this helps.

[cookie_monster]

cheers kleky!....il c if som1 will let me borrow ther MAF to test out in my car lol.....highly unlikely but hey worth a try..........(however just took the car on the motorway today with the sensor unconnected to the MAF) and it flew like a baby........
....il post once i find out what it is anyway.....
thnx once agen!

cookie monster!

[scoutfinch]

high all well there is lots about mafs n stuff....but had maff replaced lasted bout 2 days now problem back....everything fine n dandy then limp mode!!!
also been to main ******* want to me to part with just under a £1000 for a new turbo but its the boost pressure valve or dump valve same thing....
any ideas please coz its getting close to crimbo & i not spending a £1000
many thanks scout

[JEZZER]

i have a slight knowledge of this problem as i see it ever other day.90% of the time it always proves to be the air flow meter.they all seem to act in different ways at different rev ranges.have been known to purchase the replacement part for as little as 60.00 if you shop around.quick to fit and instant results

[Marc97]

I used to have knowledge of turbos in my day but I've heard now that turbos have variable vanes???? ***?
Anyways, in my day, a wastegate was basically a valve that opened and shut which was operated by an actuator.
When there was low boost, the vaccum inside the inlet manifold was low and the wastegate was shut which allowed more boost from the turbo to go back into the engine, air + fuel = power!
When the boost reaches a preset level, the vaccum inside the inlet manifold pulls the actuator which then opens the wastegate, allowing boost to travel through the exhaust system therefore reducing boost back into the engine to prevent an overboost situation (bad!)
A cheap/quick method of improving the performance of a turbo'd car was to fit a bleed valve into the vaccum pipe which operates the actuator, allowing vaccum pressure to be released through the valve instead of reaching the actuator meaning the wastegate would be closed for longer and which then would generate more boost.
If the newer Passats do not have an external actuator then I wouldn't have a clue how to fix it. Other than that, I would suggest removing the pin from the wastegate to actuator rod and vigorously working the wastegate backwards and forwards for a bit and maybe giving the hinge a bit of lube while you do it.