rmoleman

86 944 Turbo
Driving to the store today I got stuck behind a slow car on a four lane road. I was in third gear and going fast enough that no down shift was needed, just press the gas pedal and let the turbo do the rest. Except just as I hit ~3k when I expected the turbo to come on strong the engine starts to make sputtering noise and the car lurches under acceleration as revs build abnormally slowly. The dashboard boost gage was at it normal maximum. The car drives normally in 1st and 2nd, but the same problem occurs in 4th and 5th.

I am guessing this is some problem with the waste gate. The waste gate looks original so it has 55,000 miles on it. Has any body had a similar problem?

Zeff

there are several threads about this... could be vaccum problem or ignition. How old are the plugs/wires? Also has the car been sitting for a while?

Ski

Give her the old vac line check and check the intercooler hosed and the one at the throttle body.

You may be hitting boost protection, if the car is stock - which could be related to the wastegate.

rmoleman

The car has not been sitting. the plugs, wires cap and rotor are less then 6 months old.

Zeff

if the car hasn't been sitting go over the vaccum lines like Ski said. Hope you find the culprit.

Tom M'Guinn

It does sound like a classic weak ignition though, especially if it runs fine in lower gears or under less load...

Any chance you have moisture in the cap? Sometimes a leaking waterpump will condense into the cap... Boots on tight? Coil ok?

Assuming its not the ignition, I'd next check the bypass valve and the line to it, and the big intercooler couplers.

pozican

When this happened to me it ended up being that rubber boot that goes from the IC pipe to the intake.

It has a small crack in it, and I didnt really notice for a couple troubleshooting sessions.

rmoleman

15 minutes on the interstate at 60-75 mph and the problem went away.

Tom M'Guinn

Any chance the ignition got wet -- any signs of coolant leak?

testarossa_td

Might I just mention the ole TPS. Throttle Position Switch for search.
or the AFM Air Flow Meter tracks.

toddk911

+1