2.5tdi V6

[Andyjbee]

I have just purchased a 2003 A4 SE model, 150k, i'm very happy with it as it runs like a dream and I only paid £600 with a long MOT. However during this cold spell it takes a few turns to start followed by smoke when it eventually starts. Also when it's a cold start there is no boost only when the car warms up do I feel the boost. The EM light is on and I have ran diagnostics and it's come back with intermittent ground problem on MAF sensor. Just wondering if anyone has had a similar issue. I've not replaced the MAF sensor yet purely because that error might well be a red herring. Thanks in advance for any help.

 

[pauldazzle]

Clear the code & see if it comes back. If it does replace the MAF. Strongly advise you get a genuine MAF, not aftermarket. Buy cheap, buy twice.

 

[Andyjbee]

Thanks Paul

 

[xs2man]

I can testify to buying only original MAF's. Too many times I've tried to cheap out and been stung.

 

[sumo]

Is it any better if you unplugged it?

 

[Andyjbee]

Ok a quick update with this. I have replaced the MAF with a Denso part. Light went out initially, however I still have no boost when cold and when the car warms up and I have boost it's started to judder at low speed, more so when I let my foot off the accelerator. I now have a new code P0102 MAF sensor signal to low and the EM light is back on. So I still have the same issue with a new MAF but now with juddering also a hissing noise which I didn't mention in the OP is coming from the air box. I have googled the error code but most results are to replace the MAF. Thanks in advance if anyone has any info.

 

[abyrne153]

Check the inlet hose especially where it connects to the turbo. They split at the jubilee clip and it throws up a false maf error code.

 

[Andyjbee]

Just an update on this, I have found out that my VNT actuator is jammed. Mechanic says he can strip turbo down and clean but be prepared for the worse case scenario and purchase a new turbo in case things go bad. In the meantime I've been looking at the Mr Muscle solution but can't find anyone who's done this on a 2.5TDI V6. I'm guessing it's because of the lack of access to the EGR, so more research resulted in looking at the Terraclean and was wondering if anyone has had any experience with this method and would it free up said jammed actuator?

 

[LayerzA3]

Andy, does the actuator move when you start the engine (have someone check) the actuator is super stiff with the bracket done up, it will not move like a 1.9 will.
I've Mr Muscled my 2.5, trick is to take the downpipe off - pull it to one side and make a cheap gasket from cardboard or cling film to hold the foam in and stick the pipe/straw through that and work the actuator.

 

[Andyjbee]

Looked at taking the down pipe off (Is that the hot side?) but the 2 top nuts I can access and loosen without a problem but just haven't got the tool to do the bottom one. I had a local garage run some diagnostics and it came back with faulty intake manifold flap (motor) but not to sure if this is the problem. Didn't want to lay out best part of £450 until I get this Actuator sorted.

 

[Andyjbee]

I know it's been a while, I managed to get the actuator nice and free following the advice off LayerzA3 (thanks for that) but unfortunately still no boost. However I read in a post regarding the N75 valve or the turbo pressure controller. So got a price for a replacement, simple to fit and BOOM instant turbo.
Not sure if I mentioned in another thread about a loud hissing on boost but located it to a cracked intercooler. I have replaced the intercooler and I'm just amazed at the difference it's just a totally different car. Took it for a run up to Scotland (from Manchester) last weekend and was averaging around 38-40mpg didn't want to blast it as fuel economy was more important to me than how quickly I got there. So to close thank you to everyone who offered advice if I was a bunny I'd be a happy one.

 

[LayerzA3]

Glad you got it sorted - I've got a few projects on the go and my A4 works "well enough" but I'm sure I've got an N75 or vac issue too so need to replace the lines at least.
What N75 did you use and where did you source/how much was it?