Why???

[BigBlueChevy]

Hey ya'll,
Old girl is having a bit of an issue it seems. Leaving walmart earloier today about 5 minutes into my way home I lost boost. Guage read a vacumn, and you could HEAR the turbo clearly not spooling. I lay into the throttle more and still nothing.

Got to a stop light and I heard the turbo "spool up a little"(like you just started the truck after sitting all night and its just "waking up") Accelerated, and low and behold I have boost. Climbed as normal, but as soon as the TCC locked at 45mph, boost dropped again. Again, couldn't get the turbo to spool up.

Finally got home and reved it, still no boost(and you could tell the engine wasn't getting air) Guage went down as manifold had a vacumn now. Shut it off and checked everything, intake was clear, compressor shaft spun completly normally with no play at all as always, wastegate gave me resistance with vac line plugged in and without it flopped normally(seemed a little tighter than usual but not by much. Vac lines are good and nothing else seems to be wrong.

Suggestions???

Maybe its karma? I've been talking about getting an ATT the past few weeks and even have a picture of it in the truck to show off to friends.

Thanks all. I have to run to work now and won't be back till 8 ish but any and all answers will be appreciated.

 

[Dieseldad97]

How's the air cleaner look? Maybe pull it off and run her a bit and see if it makes a difference. Good luck.

 

[Turbine Doc]

WG solenoid ??? idle thumb check isn't sufficient, you need to run with gauge at power, where are you reading vac before or after the WG sol, pump could be making vac, but if solenoid isn't opening for max vac applied WG won't stay shut fully, just a little open on WG and you won't make boost, also check the "can" on side of the turbo, if diaphragm has a leak it won't hold vac applied, and WG will open.

 

[BigBlueChevy]

The gauge itself is tapped into the lower manifold on the drivers side. Its night out right now so a lousy camera phone won't provide you guys even a half decent pic. (Hell I just remember I never showed you guys )

I was "reading" vacumn by reving the engine, the boost gauge went backwards till it hit the needle that wont let it go any farther back. (Reading vac/boost through the manifold not solenoid. Sorry for confusion) I have no clue whether or not the solenoid is providing vacumn. Thats a good place to look though. Again, I'll have to look tomorrow.

Driving to work it did it again. TCC locked, after 45mph and after about 30 seconds boost dropped off. Same as before. Once I stopped, I had spool up again.

Coming back home from work(after 6 hours of sitting) was different. I decided to drive half the way home under 45 to avoid locking the Torque Converter, I made boost the whole time. It did its usual drop off then spool back up but no drop off and no response afterwards. The other half I went faster and had no problem at all. Even with the TCC locked. ugh, so confused.

I can note however, that it does feel or sound like not I'm making as much boost as before(the problem that is). Guage seems to varify that.

I'm thinkin solenoid. Which gives me all the more excuse to get the ATT faster

 

[buddy]

Can you define how much boost you are used to seeing?

More than likely one of your plastic vacuum tubes is cracked. So when you are into it it some vacuum to the wastegate actuator.

Look around the solenoid and around thermostat housing where the bends and things are.

Get a vac guage and check for vacuum coming from vac pump then at the actuator.

If it is the solenoid and you want to get by for now you can hook vacuum pump direct to wastegate actuator with some vac hose and rerouting.