997.1 Turbo Pressure & Performance Question

[stumcnu]

After a long search and a lot of help and support on this forum, I finally purchased a 997.1 Turbo last month.

Stock car, 08 registered, black on black. So far I'm really enjoying it, but I do have a question about performance.

I've noticed a couple of things that are making me wonder whether there might be an issue:

1. At high speeds (70mph plus) the car doesn't seem to pull as much as I'd expect through the rev range - once past 4,500 rpm in 4th, 5th or 6th, the power seems quite 'linear', rather than there being a second kick from the turbo
2. Using the dash pressure gauge (which I realise gives requested rather than actual boost pressure) the reading yesterday never went past 0.6 bar (although this was the first time I've checked it, and the road surface was quite wet - not sure if that makes a difference?)
3. Occasionally if I floor the car on the motorway, there's quite a loud 'hissing' from the rear - can't tell if it's exhaust or engine-rated - and I don't think it appears consistently

Having done a bit of reading, I'm going to try a pull test today - letting the car get to 2,000 rpm in 5th, then flooring the throttle and checking the boost pressure in normal and sport mode, where I think I should expect 1.0 and 1.2 bar respectively. Is that correct?

I'll likely take it to my Porsche specialist this week for a bit of investigation, but any thoughts in the meantime would be gratefully received.

Thanks, as ever!

Edited by stumcnu on Sunday 5th October 07:50

[IMI A]

Doesn't sound right. My one has areal rush to the red line from 5000 rpm and is also stock. Even in non sport mode it regularly hits 1 bar.

You're on the right track though. Stick it in sport mode and from 2000 rpm in 6th ay full throttle you should see 1.2 bar if all is well. If not sounds like a loose hose and boost leak.

[s3nick]

I wouldn't want to be going out and flooring it under load with the noises you are describing.

You are not running the correct boost either so you seem to have a leak somewhere and you do not want to over spool the turbo.

Are you local to london?

[stumcnu]

Thanks all.

I've been out of London for the weekend and have just driven back in. Took it incredibly steady on the above advice - barely registered turbo boost.

Will take it into the specialist local to me (Tower Porsche) this week.

Appreciate the advice...

S

[s3nick]

stumcnu said:

Thanks all.

I've been out of London for the weekend and have just driven back in. Took it incredibly steady on the above advice - barely registered turbo boost.

Will take it into the specialist local to me (Tower Porsche) this week.

Appreciate the advice...

S

Ahh no probs im in North London and could have met you to see if I recognise the noise.

Glad you got back safely.

[gaxor]

Could well be the turbo actuators which adjust the pitch of the variable vane turbos they have a reputation of sticking.

It's not a massively expensive fix and easy for a technician to check

[gaxor]

Could well be the turbo actuators which adjust the pitch of the variable vane turbos they have a reputation of sticking.

It's not a massively expensive fix and easy for a technician to check

[gaxor]

Could well be the turbo actuators which adjust the pitch of the variable vane turns, they have a reputation of sticking.

It's not a massively expensive fix and easy for a technician to check

[stumcnu]

Fingers crossed. The car goes in later in the week to get checked out, so I'll report back after that.

Thanks again all.

Stuart

[MrTickle]

Gave mine a whirl last night following your post to make a comparison.

Sure enough, 2.5K RPM in 5th and it went straight to 1.2 bar in sport.

[stumcnu]

All sorted. Turned out to be a loose clip around the turbo unit. This was causing a loss of pressure, which in turn was tripping a number of sensors. As such I wasn't suffering only from the loss of boost pressure, but the power was being held back because of all the senor errors.

I'm assured by the garage that I should expect to experience a significantly faster car :-) I've yet to test - looking forward to that!

Only cost an hour's labour too.

Thanks all for your advice - much appreciated.