Charlie360

Hi All,

Although I've been lurking on the forum for sometime and learning a lot from you all, I haven't posted until now. Apologies for the log in name I've been converted from being a 360 modena owner to a 01 996TT and am based in the UK.

My problem is that I recently had a minor rear shunt in the car and it's been in the body shop for a new rear bumper and other minor components around there, the airbox was not damaged and nothing forward of that seems to have had any problems. I have got a higher flowing exhaust and the 200 cell cats on the car plus a stage one type upgrade (so running around 500bhp at the fly wheel). I collected the car from the body shop last night and on my journey home could not get more than 0.5 bar of boost (with the upgrade it usually peaks at 1.1 and can sustain 0.8~0.9 bar) so I returned to the garage today and had them check the diverter valves for leakage and also put the diagnostic computer on the car (I had a coil pack failure giving a slight misfire a few months ago which resulted in lower boost) but neither showed any fault. The mechanic therefore thinks there is a pressure leakage else where in the system and wants to take it all apart again!! after the accident I don't recal any lack of boost when I drove it to the garage, so am not sure if its as a result of the shunt. If anyone has any experience of such issue or can shed light on whether they think it's an electrical or physical (ie pipe leakage) fault I'd be most interested. Thanks in advance for any replies and what a great forum.

Periokid

If the diverters are fine then I would first suspect a leak. It could be a broken intake hose after the turbos. There is a lot of piping and it could be before or after the intercoolers.

It could also be a loose clamp to any of these hoses.

Check the hoses before anything else.

ebaker

Check the hoses that connect to the diverters.

Charlie360

Thanks for your responses guys, I have had a couple of further thoughts and comments;
As stated previously, the car reaches 0.5 boost fairly easily and quickly, well at least as quickly as normal, if there was a leak surely it would take longer to get there and the ceiling boost would be variable rather than a standard 0.5 everytime - it was this fact that made me wonder whether it was an electronically imposed limit.

ebaker

Maybe you got some low octane fuel.

Periokid

Perhaps, unless the system is sealed until you reach that level of boost. Some loose connections may only open at pressure. Check allthe clamps and fittings.

Charlie360

Well the mechanic has pressure tested the induction system now and found no leaks so it's either a turbo problem or an electrical fault somewhere! more time on the computer then.........

Gilhart 54

Charlie 360,

Give your battery a full charge then take it for a run. I recently installed a smaller battery in my TT for a track event and found that it was incapable of handling the electrical needs of the TT. I was getting .4-.5 bar with the small battery and back to .8-.9 with the original Porsche battery reinstalled.

Your battery may have lost charge while sitting at the repair shop.

Rick

Charlie360

Thanks for all your responses - the battery was a possibility as it was completely flat and therefore all the warning lights were coming on - however everything apart from the boost issue was solved by a complete battery charge and run. So a couple more days of head scratching and pressure testing the induction system finally uncovered a "frequency valve?" in the induction system that was sticking half open (Not a diverter valve) so that was sorted and it now seems to be back to full operating boost - which is nice!