Well I'm Stumped

[Wilko]

Help.
One of my colleague has a standard TT225 and it won't run more than 0.3 bar boost.

Error code of pressure loss between turbo and throttle body. Check DV

DV is fine, maf is a known good one, and reading 190g/s max, with n75 duty cycle of 80%.

All of it suggests a massive boost leak, but the fuel trims are spot on at 0.0 and 0.8,

Also a boost leak this big should be obvious and noisy.

I've checked all the visible hoses and had a quick feel around the ones you cant see, and can't find anything. Also all the vac piping seems ok. All clean with no tell tale oil on them from leaks.

Anyone got any ideas on where cupra r pipework leaks, or ever seen a split intercooler? Any suggestions.

 

[Feel]

woohoo, our chance to help you for a change

190g/sec at 0.3 bar is bloody good - stock boost is 0.8 IIRC. 80% is low for a leak, isn't it, I thought it would be at 100% if it was a leak? Never seen anyone post those figures up.

Actuator or N75 is my guess, it's not trying to boost (although...). Blockage in the TIP? You checked the turbo outlet hose (red one)?

N75 hose off charge pipe is common(ish), "F" pipe on left hand end of manifold, and DV hose off charge pipe can split on the inside of the first bend where you can't see it. Lower intercooler hose (LH from front) came off mine, but still looked to be on.

 

[goble]

wastegate jammed?

 

[DPJ]

Faulty MAP sensor?

 

[Wilko]

The airflow suggests that the turbo is shifting the right amount of air, so it's not actuator or n75 probs. Air is getting to and out of the turbo at the right rates.

The flow is there, uto the turbo, but it isn't getting to the throttle body. All points to big boost leak, other than the fuel trims. Can't find the bugger though.

It's big enough that I should be able to hear it.

Map sensor must be ok, as the car accelerates about as it should for 0.3 bar boost. ( 9 sec 0-60)

 

[DPJ]

But surely the fuel trims would be out with a leak of that proportion.

 

[Wilko]

you would think so dave

 

[Wilko]

If it was map, I'd expect loads of timing pull as it would be running too far up the timing tables, but there isn't any

 

[goble]

wastegate jammed as i said

 

[DPJ]

Did you log 115/118 ?

 

[Wilko]

wastegate jammed as i said

But the turbo is moving the normal values of air, so it's doing as it should.

 

[Wilko]

Did you log 115/118 ?

Yep.
Requesed around 0.9 actual around 0.2 at the bottom end rising to 0.35 at the top.
Duty cycle peaks at 80%

 

[DPJ]

If the wastegate was stuck open, would the N75 still appear to be doing its job?

 

[Wilko]

If the turbo was only boosting at the equivalent flow of 0.3 bar boost, it would not be moving 190g/s through the maf.

 

[DPJ]

If the turbo was only boosting at the equivalent flow of 0.3 bar boost, it would not be moving 190g/s through the maf.

..which might suggest it's boosting more than 0.3 bar?

 

[goble]

4.35 psi??????????

 

[Wilko]

Right
ECU requests load. Main load sensor is the maf, and what the n75 and wastegate control loop looks at. All the map does is give set timing from the timing tables.

Boost is a function of flow into the head. If the flow is going through the turbo, but not all getting to the head, you would see normal flow at the turbo/maf, and low boost.

There is a major leak, but I can't currently find it. I guess I need to look at the instantaneous trims, as the long term ones soon come back into line if there are no major vac leaks, and the car is driven off boost.

 

[DPJ]

Right
ECU requests load. Main load sensor is the maf, and what the n75 and wastegate control loop looks at. All the map does is give set timing from the timing tables.

Boost is a function of flow into the head. If the flow is going through the turbo, but not all getting to the head, you would see normal flow at the turbo/maf, and low boost.

There is a major leak, but I can't currently find it. I guess I need to look at the instantaneous trims, as the long term ones soon come back into line if there are no major vac leaks, and the car is driven off boost.

Makes sense. I've learned from you John, but not enough yet. Change the thread title to "Well we're stumped."

 

[Feel]

How long has he had the car?

 

[Wilko]

Sometimes a few brains are better than one.
I was looking for some of the cupra r boys experience of mechanical leaks in the turbo-TB induction pipework. I don't want to go to the trouble of ripping his bumper off, as he has a warentee, it's just I know the dealers will have no bleedin clue.

I was looking for 'it'll be the turbo outlet pipe. They always fail' or something along those lines

Phil
It's his wifes. First time he's driven it. He's got a 996C2 and thought it was guttless for a 225. He was right.

Thanks for trying guys.