[s-cars] Stumbling under acceleration.....probable boost leak?

Jim Fleischer jim at almgt.com
Mon Nov 23 17:36:53 PST 2009

Hey guys,

Just returned from a 900 mile mostly highway trip from Texas to Colorado....Noticed shortly after heading out that there was some significant, albeit inconsistent stumbling upon acceleration.  Could half-throttle it and keep it from happening in the lower gears, but fourth and fifth suffered under harder acceleration at lower revs.  Checked all the obvious places for a tear, and tightened up all hose clamps I could get to easlily.....no difference.  Car still pulls pretty well at upper RPMs, but not smoothly by any means.

Was able to replicate this with more regularity as the trip went on, and seems to have gotten worse as the altitude increased.  Was downright difficult at 10,200ft in Leadville, CO.  Disconnected battery overnight to reset ecu, etc. and found no difference today.

My thought is a boost leak, but cannot see/find a tear, and revving the motor in place does not put enough load on to make anything readily apparent.  Before I start tearing off hoses, etc. anything else I could be missing?  

Car is a 95 s6 avant and just turned 80K miles this trip.  Hoses, POS, etc. all original.  Replaced spark plugs and wires @ 60K.  Checked spark plug torque, all good.

Any and all help appreciated!  Do not want to take this in to anyone if I can help it.

Best regards,

Jim Fleischer
'95 s6 avant
'83 ur

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