disappointing dyno results - HELP

[cobalt911]

Hello all,

Thought I would trundle down to Surrey rolling road and get mine checked out. Was gutted to see 267HP after looking at the neinmeister results in the forum. Charlie at SRR thinks the engine is sound and it is possibly and ancillary such as Vram or the cats. I see the vram issue elsewhere but how can I check that it is all connected and working or is it a job for Northway? He seemed to think that others with vram show more kick at the top end and it can be felt whereas mine was progressive and only reached the 267.

Crying into my beer tonight I suspect but before I get the credit card out once again any thoughts??

Cheers all for any replies..

Mark

 

[sidned]

Mark,

Don't panic just yet. This is exactly what happened to me, and about the same difference in BHP! I took it to my local Indy and they had a machine that can tell if there is a leak in the vacuum. There was, and it was just a case of tracing all the pipes until they found one of them that had been disconnected. They reconnected it and all was well again!

Darren

 

[cobalt911]

Thanks Darren,

Did you do a dyno run afterwards as well? Would be interesting to see the difference it actually made when the pipe was reconnected. I hope it is a simple thing like that - I had a similar issue with the air-con and when I opened up the relay box in the back a cable had come astray!
I do think my cat may be on its way out too though....been smelling a little heavy for a while!

Cheers,

Mark

 

[sidned]

Hi Mark.

I did get it re-dyno'd and it came back at 272.3bhp which is still down, but way better than the 255 or so I had originally. The guy who owned the rlling road suggested it may have been due to the Supercup exhausts. I would have thought they would have added bhp, but he said sometimes they need an engine remap to get the best of them as the standard engine map is expecting a certain amount of back pressure. It sounds too complicated to me, and I didn't want to mess about with remaps in case I had trouble insuring her. I'm happy with the performance as it is. []

Darren

 

[Mark Elder]

Mark,
Did you get a graph of the power/torque from your dyno run?

If yes it would be worth comparing with the two different graphs of the dyno runs on Steve Humphries car - in the post http://www.porscheclubgbforum.com/tm.asp?m=372779

It was Steve's car that had part of the Vram system disconnected in it's first run - if the low graph shapes are same as yours it points to similar fault (and therefore easy to fix) - hopefully!

 

[pse_SC]

How about getting your car plugged in on the diagnostic? When for the one (and only) time I had mine dyno'd, it was a bit down like you say - turned out to be an oxygen sensor. When replaced, made all the difference[]!

 

[cobalt911]

Thanks Maurice,

Took it to Peter Tognola today for a quick check. The resonator flap and vram stuff is all resetting correctly when the ignition is on but I did notice the other day that when I removed a hose there was no 'hiss'. I mentioned the vacuum stuff to Peter and he wasn't quite sure the route I was going down. The diagnostics showed no faults so they will have it in for a day in a week or so. Possibly getting a new cat fitted at the same time (but seems a bit expensive!) to see if that helps but no more insight as of today....

Cheers,

Mark

 

[cobalt911]

OK - interesting discussions with Paul at Northway too. It would appear that the 'hissing' you can hear when disconnecting a vacuum pipe does not always appear and can be a little misleading?!? as long as the resonance flap and vram actuators reset then vram should be ok...mine do seem to reset (although it is not always a pronounced 'click'...maybe the lack of vacuum again? Anyway, when I pull the tube closest to the back (front) of the vram I never get any type of hiss or sound of air!

So, there are 3 more avenues. The first is the oxygen sensor (Peter at Tognola did see this as acting 'sluggishly), there is the catalyst getting old and building up carbon deposits, and there is possibly still something up in the vram. There is also a belt that may need adjustment but Paul said that could be engine out (ouch) so I am not rushing into that!

The plot thickens.....my wallet thins!