After a long series of messages here on this forum, I decided to bring my 997.1 Turbo in for service. The issue was a boost gauge that only reads 0-14psi instead of the normal,0-18 psi. In addition, the boost values I receive are never more than 10 even with the sport chromo. It would seem that perhaps, the gauge was programmed incorrectly, and if it went from 0-18 like it should, maybe the same bar graph values would now be at a different scale and the boost would be ok. Was supposed to be easy.
Brought in the car today: This was the technicians write up:

Did a road test. The boost never read more than 7 or 8. In sport mode never more than 10 and it was inconsistent. Did a complete scan and another on tester 4 there are no faults.
Put the car on the lift. Verified the turbo actuators with PWIS and everything is fine.Verified the bypass valves with a vacuum pump, both work well and hold their vacuum.The two actuator rods for the turbos have lots of rust but they work well.
Did mother road test with another tech and psis and the turbos are not boosting completely and are unstable under acceleration.
Verified on (ppn) the procedure for testing the turbo pressure. There is no procedure or special tool.

That's it. Got a call that the car was ready, come and pick it up (1 hour drive).
and the gauge still reads 0-14 instead of 0-18. They acknowledge there is a problem but return the car and say there is nothing that the manual says can be done.
What the heck is this?? What are mechanics doing in a Porsche shop if they cant' diagnose a problem?

What now???

 

No one has any comments?

You know I gave the report to my neighbour and he said it's like taking a car with a flat tire to the dealer, he tests drives it, and then gives you back the car and says there's a problem with the tire. No resolution?

I'm going back there tomorrow, but I'd like to have some ideas to tell their service people where to look. Seems like they don't know.

Ok, car does not make enough boost. Never gets higher than 10. Boost is erratic. As a matter of fact when I tested it today, the boost got up to 10 then dropped to 6 and went back to 10 several times in a matter of 1 or two seconds. Just oscillated back and forth. But the acceleration did not seem to oscillate back and forth.

What are the components involved? You have the turbos, with actuating rods, waste gates and this is all they looked at. What about sensors? What if one of the turbos is not spooling right? How does this work?

The car has a CPO. Aren't they required to fix problems?

 

Well, the first question is whether it's the gauge that's faulty, or if there is something wrong with the turbos themselves. Based on this:
...it sounds like it's not merely a faulty gauge. So they need to trouble-shoot the turbos and figure it out... I don't think anyone on the forum can solve this via the computer; you just have to put pressure on the dealer to get to work and find the solution.

Did you buy the car at this place?

 

Yes, the car was bought at this dealer.

 

Well then they need to step up their game and take care of you.

It's obviosly not an intermittent problem; the tech was able to replicate it and noted that "the turbos are not boosting completely and are unstable under acceleration." So they need to trouble shoot step by step and find out what it is. If they can't, they can get help from Porsche; dealers have a way of consulting with factory techicians on tough cases.

Try again; insist that they figure it out; if they won't or can't, you might need to call Porsche and get one of their reps involved. Or, try a different dealership.

 

It would be great if they had another turbo with SC on the lot - you could at least go out, have them turn that car on and see that the linear boost gauge goes to 18 not 14 like on yours. That would be very visable and credible evidence that at least one thing is wrong.

 

Well they don't have one. and the jury's still out on whether the gauge should read 0-18 or 0-14. On youtube, 0-60 some of the movies show gauges reading 0-18 or over 1.0bar (up to 1.4). But yesterday, someone with a 997.2 said the gauge reads a max of 1.0. Now, if I hadn't seen the 0-18 I would never have looked into this. Afterall, it's not easy to use max boost all of the time !

 

I have 2008 turbo and gauge reads from 0 to 18 and it reads like that even when boost is zero. Just went out to the garage, turned ignition on (didn't start) and selected the boost gauge - here's what it looks like. Show this to the service guys and ask why yours doesn't look like this. As I said 2008 turbo with SC option. Not sure why the picture is upside down - when I select to upload it is correct...but open it, flip it around and you'll see the range of psi from 0 to 18,

 

Thank you for the info. I have a 2007 though, so I am not sure. At this point I have to be absolutely sure.
Thanks

 

My '07 does not have SC and max BAR/PSI are 1.0/12. My last TT had SC and the gauges were 1.2/18 respectively. My GT2 was even higher. Looks like it shows max performance capability that the TT came from the factory with.

 

My 07 TT with SC shows 18psi

 

What dealer?

 

Your dealership should be doing this, but if they won't, you can log requested boost and all the other engine parameters and determine if:

1. Is this just a gauge problem (ie boost requested is appropriate, just not being displayed.)

2. Is there a problem with your AFR that is causing boost to be pulled.

3. Is boost being pulled due to AFR, or is boost falling with IATs <50, normal AFR, timing, etc...suggesting a leak.

This would provide a lot of information to help you. Even if you are unable to repair the problem yourself, you could provide it to the dealership as evidence of a problem.

 

Log boost, afr, timing advance, iat and throttle position for a full 3rd gear pull (turn off PSM it meeses with timing advance) and post up (or plot in excel so we dont have too) and one should be able to get more clues here...

 

I just received a durametric, so I presume I can do this. Need to research a bit though.