bw993

+1...
Tim at SFR, when checking 951s for air leaks would lite a cigarette, take a deep draw and exhale the smoke into the J boot after the AFM. He had a cap on the J-boot with an 1/8" nipple that had a hose attached to it. After filling the system with second hand smoke he then hit it with compressed air and looked for leaks. Worked every time according to Tim.

raleighBahn

By the time I blew enough smoke in there I'd be up in the kitchen rooting around for salt and vinegar kettle chips.

beamishnz

No turbo authority (so don't shoot Lart!!) ... but I had this very similar symptoms on an S2 and it was a +ve to earth short that only occurred under acceleration. Battery was not clamped properly and +ve terminal was tilting and touching the chassis under acceleration ... which caused everything to die and then revive the moment the acceleration was cut. Simple and stupid, but took a while to find.

My excuse is that batteries are buried in the boot on RHD cars

Biscuits704

Ditto - same happened to me.

Felt like you were hitting a brick wall. The overboost up until that point was nice though

sdrake

A little preasure and some soapy water and bubbles everywhere.

sdrake

Well, I'm still stuck here. I replaced the cycling valve and all of the vacuum lines and clamps, even replaced the banjo bolts.

Car is still dead lethargic when first started and has the over-boost (falls on it's face) issues under moderately hard acceleration.

Any additional thoughts?

thanks folks

mel_t_vin

Scot, do us a favor and list all parts that have been [recently] replaced.

How old is the fuel pump? Clean filter? Clean wiring/connections? How old is the FPR?

At what reading on the in dash boost gauge does your issue present itself...0.8, 0.9, 1.0 bar? Do you have a mechanical boost gauge? If not, suggest you install one.

Suggest attaching a pressure gauge to the rail and spending some diagnostic time on a dyno, with an exhaust gas analyzer in the tail pipe, to verify fuel pressure under load and AFR across the RPM range/power band.

944crazy

Have you checked the vacuum line connection at the wastegate? It can easily be overlooked when checking all the lines in the engine bay from above.

Ski

I would start with Vac Line routing as mentioned. I'd put a stock chip in over Autothority. Have a spare KLR?

Rando944

I had the exact same symptoms. Problem turned out to be a leaky hose exiting the intercooler. Cracked on the bottom, so it was hard to discover until the hose was off. Clark's Garage said these symptoms are caused by a vacuum/boost leak, and he was right.