Turbo/boost issues - 1.8T 20v

Hello,

I'm having problems with my car at the moment. When I put my foot down, I hear a whooshing sound but get no boost. The car sometimes stutters a bit and doesn't accellerate very well.

I've checked/changed all the turbo hoses for brand new silicone hoses....they're all connected nice and tight. I've changed the N75 valve and fitted a new turbo this weekend. I have a Baileys DV30 diverter valve and a new MAF was fitted in July.

I've plugged VAG COM into the car and no fault codes have come up. The whooshing sounds like it's coming from the passenger side of the car - possibly where air is beig drawn in through the air filter.

Any ideas???

Cheers,
Kav

 

TIP pipe come off or split?

 

TIP pipe is also a new silicone pipe...

I've heard that people have had boost/performance problems with the hall sender (camshaft position sensor) and that it doesn't always come up on the diagnostics. What do you reckon?

 

sounds like a boost leak to me...

rev the engine from the throttle body and see if you can hear air escaping. It should be obvious if its leaking

 

is the intercooler cracked for some reason?...

 

Quick update...I've changed the camshaft position sensor and placed a standard diverter valve on there but still no luck. I rev it up when it's parked up and can see that the pipes to and from the intercooler expand a bit under pressure. The whooshing sound is only heard when I'm driving and put my foot down quickly....I can't seem to replicate it when it's idling.

I did a scan with VAGCOM and the only error that came up was 16500, which I believe is something to do with the coolant temp sensor, but doubt that this will have anything to do with the turbo problem. I cleared the DTC, went for a drive and it didn't come back up when I re-scanned.

Would a cheapo universal cone air filter possibly cause problems? I'd have imagined that if there were any probs with the air supply that I'd get a CEL or at least an error code??

 

Well, for starters, as a rule of thumb, you should first try to understand what is going on, and why is going on, BEFORE changing parts.
This can lead you to spend tons of money, and then blame if on the car

So, it looks like you have an air leak.
Do you have a boost gauge?
If you do, what's the reading when idling and when getting your foot down?
If not, can you pressure test the system?
This way, you will ear from where the air is getting away.

 

Thanks for the reply HidRo,

Too late....I've already spent tons of money and blamed the car lol

Now that my savings account has all but disappeared, I have admitted defeat and handed it over to a tuning company to pressure test the system.

It's only now that I've found a cheap/easy way of pressure testing it myself using a tyre valve and a plastic cap, but ah well...at least they'll check everything thoroughly.

I haven't got a boost gauge at the moment, but I think it will be a good idea to get one.

An expensive lesson learnt

I'll let you guys know what it was when I get a call back from this company...

 

Interesting...

I've just had a call from the tuning company. They tested the boost and have seen that the ECU is telling the N75 valve to release the pressure at 0.4 bar. Does this sound like limp mode? The CEL doesn't come on and no error codes are coming up.

He reckons that it's possible that the ECU has been fiddled with and told to open the wastegate at 0.4 bar....but why on earth would anyone want it to do that???

Confused

 

does sound like limp mode pressures..
whats the requested boost? or is that it? 6psi?

 

No idea matey...the tuning company just said that it's opening at 0.4 bar.

They put it on the rolling road and said that it's running lean....looks like it could be a MAF issue. Annoying because I got the MAF in July. Strange that it isn't throwing error codes if it's having issues with the air intake.

Waiting for another update from them...

 

Have you messed with the wastegate rod? Does it still have the nuts in there?
If it's you don't change anything, it's strange that it changed. But, could you test another N75?
And better yet, have they REALLY pressure tested the system?

 

Nope - I left the wastegate rod well alone on the new turbo.

I bought a new N75 valve on Saturday and also tried my sister's TT one so it's defo not that.

They've had it on the dyno and it's running really lean. It's only kicking out 115bhp at the mo. I think I have a spare MAF in the garage, so will take that to them tomorrow. In the mean time they'll get someone in to check the flash on the ECU to see if it's been messed about with.

Can't wait to have it sorted!

 

Agree. 0.4bar manifold pressure is the N75 on 0% duty ( straight connection of actuator to boost pressure).
This is normally associated with faults if the ECU is limp mode.
If there no faults then you may want to check the recirc valve to see if that has not failed and is dumping the boost pressure back to post MAF. Failing that your MAF is probably dead!

 

Thanks mate...I reckon it's probably the MAF that's gone. Got a brand new one I'm gonna take up there tomorrow and see what happens.

I'll keep you all posted!

 

Hi folks....

They tried changing the MAF and still nothing.

Only thing left is to check the flash in the ECU itself to see if it has been corrupted.

 

genuine maf???? i had a spurios one lasted 6 days!!!!!!!!!!

 

Well, the same question again... Do you have a boost leak.
Only by presure testing, you will know for sure, and if you say that you can hear the boost louder, you either have a boost leak, or maybe the manifold to turbo bolts un-done.
This will cause the sound, and the leak sympthoms.

 

Hi Guys,

Yep, the MAF is genuine and worknig. The bolts are tight...I torque tightened everything when I swapped the turbo.

The tuning company are useless. They've had my car for 3 days and achieved nothing. I'm gonna pick it up at lunch time and pressure test it myself this weekend.

If it's not a leak in the intercooler then I'll be well and truly stumped as every other possible item has been changed.

I'm really not impressed with this tuning company!

 

Ok....I've got my car back now.

The jokers wanted to charge me 95+VAT for the pleasure of not diagnosing the issue and not fixing anything. Paid 30 in the end and even that was too much.

Anyway...I took the car to another tuning place round the corner - these guys seemed clued up on VWs and have advised me to pressure test the intercooler first before I bring it back to them to have the ECU checked.

So...I'm going to pressure test the IC by capping the turbo side and using a tyre valve to insert pressure. Will I have to cap the other side or will the inlet manifold hold the pressure?

If it's not the IC and I do have to get the ECU fiddled with, then I'll have it remapped to 200ish bhp