Mk4 Golf TDi -

[Adamspoon]

I own a W reg Mk4 Golf TDi (90bhp). The car is very slow, it struggles up hills and is generally no fun to drive. It's never been a fast car but i'm sure it wasn't this bad when i got it a couple of years ago.

I've read up on the internet and found that several people have reported a loss of power problem with these Golfs, although most report a sudden loss of power which is rectified by turning the engine off and restarting it. This is not the case with mine, it's just permanently underpowered.

I've booked it in for a diagnostic test at a local VW garage (Myers Motors in Beckenham) tomorrow but don't really know what to expect.

Can anyone tell me what the diagnostic test will actually show? Will it show what Bhp my car is actually producing or will it just come up with an error code? Lots of others seem to have spent fortunes at garages fixing these error codes only to find out that there's no real difference in the perform\nce of their cars! Any tip on avoiding this?

I really want to get the car re-mapped, but it seems pointless until this problem is fixed. It is an oldish car and has done 110k plus miles after all.

Any advice greatfully accepted, as you can probably tell, i don't have a huge mount of experience!

[ImCammers]

110k on a TDI Engine isn't alot, although its hard to say exactly what your problem could be.

As for the diagnostic's it may/may not depending if the fault is intermintent show Fault codes, the best thing once you have these fault codes is to post them on here and we maybe able to help you. As for the performance, i dont think they'll see this from reading the ECU, only way of finding out this would be to put the car on a rolling road.

The cars not using an unusal amount of oil? Leaking?
Does it start first time every time? (Once the glow plug light goes out on the dash)
Using more diesel then you normally would?

[Crasher]

The rule I follow with this problem is "no power, no codes, fit a new Air Mass Meter". If your garage suggests a new AMM (often referred to as a MAF but VAG don’t use this term) do not under any circumstances let them fit anything other than a genuine VAG AMM bought from a VW dealer or from a VAG TPS which is probably where they will get their genuine parts. Don’t let any talk of genuine Bosch or OE quality or anything like that sway you, insit on seeing the white box with a genuine VW sticker on and the part number will be 074 906 461 (approx £77 inc. VAT) for an up to 99 with an AGR or AHF engine or 038 906 461 C (approx £68 inc. VAT) if it has an ALH engine. The reasons for my instance on this are varied but one is that the market is flooded with forgeries and another that I used to experience about a 50% immediate failure rate with non genuine, so far insisting on genuine I have had no failures even after 2 years. Also don’t take any advice from anyone who tells you to try the car with the AMM disconnected, I have never had this work when I have tried it and all it will do is store an AMM open circuit fault code which can confuse diagnostics work.

[Adamspoon]

Thanks for the replies. I'll get the diagnostic done and post back here with any error codes before agreeing to any work.

In response to your questions:

The cars not using an unusal amount of oil? Leaking?
Does it start first time every time? (Once the glow plug light goes out on the dash)
Using more diesel then you normally would?

No oil leak and I hardly ever have to top it up.
It has always been reliable and starts first time.
I haven't noticed any difference to the fuel consumption.


All in all it's a nice reliable car, it's just sooooo slow! I could do with test driving another 90bhp really to see how much difference there is.

[dirtyderv]

I would agree with Crasher. If you know anyone with the same engine you could swap it over to see if that works.

How long would you expect to get out of an AMM Crasher? My car is on 153k and the origional AMM as far as I know

[Crasher]

The lifespan of an original AMM was a little as a year originally but the genuine replacements seem to last a long time.

[gbrad2x]

And use a normal air filter. A mann or something stock. Performance air filters make no difference to power and will screw up your shiny new MAF sensor!

[Crasher]

K&N panel filters do not harm the AMM.

[Adamspoon]

Have been speaking to a mate at work and he reckons it's easy to replace the AMM yourself. Is this true? Bearing in mind I have very little experience and have very little equipment, but am willing to give it a go and have a more mechanically minded mate who could give me a hand. Would much rather do it myself if possible.

Also someone else suggested freeing up and lubricating the actuator might help. Said this was easy to do too. I don't even know what this is! Any thoughts?

[Crasher]

AMM is easy, turbo linkage not so.