1991 944 turbo power loss
 

Hi all hope you can help me with the problem that i have with my car,what has happend in the last month is that the acceleration as slowed down alot,it used to really shift,now not so much,i have checked all vac pipes and all that i can think of,the car runs just fine no miss fire, ticks over fine,it holds its boost in all gears, you can not falt it apart from its gone slower,as far as i now it as not been modified apart from a manual boost controller,at this time it is in a garage i think that it is a split oil breather pipe under the inlet manifold,this only happed when i was testing it after cleaning air filter to see if that would bring my power back,the garage sead that it may have been split for sometime,allso there is a vary small leak at the exhaust crossover pipe,not sure if that would make it loose power,one last thing,the engine was rebuilt about 25k ago.thanks any help would be much appreciated.

A broken crossover pipe could cause your issues, as could the broken oil breather pipe...

Have the garage pressure test the intake tract (10PSI applied through the J boot where the air flow meter attaches).. and using soapy water sprayed on the rest of the intake pieces till they see bubbles forming...

The crosover (since you KNOW it is bad) should also be replaced.

A gradual loss of power can indiacte a few things, but getting the KNOWN issues addressed first should be the priority.. Your crossover could be partially collapsed, the post turbo exhaust could be clogged or collapsed, the turbo could have supperficial damage, or damage to any of the intake / vacuum / oil vapor purge systems could all cause your issues...

Check the down pipe from the turbo. It is a two-wall design and the inner wall can collapse restricting flow and limiting power. This happened on the 88 I owned and was diagnosed by full boost being measured but low power.

To confirm, you will need to pull the pipe and look inside or scope it with a section of hose. We could not press a garden hose through the pipe.