'95 850 Turbo - Odd Turbo Behavior Following PCV Job

[scottyscott]

So I replaced the PCV system, cleaned the EGR, cleaned the throttle body and the intake manifold, serviced the injectors, and replaced the vacuum lines and intercooler hoses with silicone tubes/hoses. Necessary gaskets, etc., also re-done, of course. Previously replaced the TCV about two weeks before the PCV job. Didn't end up a screw/bolt extra or short. (Pat on my own back. Good job, given that I've NEVER done any repair work on a car before except twisting an oil filter on or off.)

First start after all the work: car fired up nicely, no DTC codes thrown. Rough idle; turns out I had the the vacuum lines from the sensor on the top left of the intercooler reversed (one goes to the EGR valve, one goes to the vacuum tree). [Unless I read the diagrams wrong...this could actually be my whole problem.] Swapped those lines and the car idles just as it did before. No other problems.

Took the car out for a spin; after a couple times around the block, took it into traffic. I floored it to make it into a tight space on a state highway...and the car burned rubber all the way across the intersection. Kinda freaked me out, mainly because of the oversteer. Subsequent tests revealed that the turbo gauge is pegging ALLLL the way to the right (past the white) when the throttle is wide open. The engine isn't cutting out as described in other overboost posts, although I'm afraid to push it for more than just a second or two. So maybe I'm not "allowing" enough time...for what, the ECM to detect overboost or for the overboost conditions to properly develop? Neither of these things should take SECONDS. Milliseconds, I would think. But maybe I'm wrong.

Mind you, the turbo behaves nicely all other times; I've yet to see more than just slight boost at 2000-2500 RPM or less. The gauge moves about 1/8 an inch into the white with WOT from standstill, at least initially. It's not until the engine reaches higher speeds (above ~2500 RPM) that the turbo starts sucking air like Rosie O'Donnell on a treadmill.

The car behaved like this previously when the fresh-air vacuum line to the TCV was unplugged. But Everything checks out: lines are connected (checked and rechecked), sensors are connected and functioning ok, no DTC codes. (Well, except 1-1-1.)

I've heard that the gauge should never move past the 3/4 position, and before the PCV job, the turbo would "stick" exactly at 3/4, even with WOT. I prefer that behavior.

Any ideas? I'd really like to NOT bend a rod. And I'm not super comfortable driving on the interstate if I'm going to NOT be able to "floor it" without damaging my engine.

Thanks.

[Matty Moo]

Sounds like the hose that goes to your wastegate isn't connected.

[scottyscott]

Sounds like the hose that goes to your wastegate isn't connected.

Yeah, it's connected.

[vjaneczko]

Smoke test? I'd also double-check the hoses are running to the right spots.

[scottyscott]

Resolved: the vacuum lines to the wastegate and the air intake were swapped. Stupid mistake. I checked this so many times, I'm not sure how I missed it. Thanks for all the suggestions, guys. Car's behaving very nicely now, and flies right up to 115 without breaking a sweat or blowing the hood off. Haven't been able to get any faster than that on the freeways around San Antonio...at least not yet.