Yesturday I was driving home from work doing my usual speeds, as I was going up a big hill (hwy 26) I downshifted to 4th to pass a truck and as soon as the RPM's got up to about 4000rpm (not WOT) and I wasn't in Boost, the car suddenly fell flat on its face for 1 second, then returned to normal. I put it back in 5th for a few seconds thinking what the hell that was, then I put it back in 4th and this time hit WOT and got into full boost and it did the exact same thing again.

 

 

I have been having very light surging issues latly at cruise speeds and on initial startup the idle is rough for about 30 seconds then smooths out.

 

It kind of felt like my Chevy Tahoe did when it was getting starved for fuel at WOT (fuel pump was bad)

 

I've replaced :

 

Ignition Coil

Ignition Module/Ignitor

Cap & Rotor

Fuel Filter

Spark Plugs and Wires

 

I'm at a loss.

Spark plugs and wires?

Check your cap & rotor again. I just figured out the reason my Subaru was running like crap (missing badly on startup, if it would run long enough it would smooth out, but still didn't run great) was because the button in the center of the distributor cap came out and there was a nice gap (slowly widening as the bits and pieces eroded away) in the way.

 

-=Russ=-

Sounds like fuel cut to me

 

get a boost gauge on it

 

line to waste gate should be checked

check your air filter too.

 

after you get the problem solved, you can chop out the bottom of the air filter box (leave a lip for the filter) and it will be like you added a couple of cylinders.

I've checked the Cap & Rotor both are fine, Air Filter is new, and I'm running Stock Boost 7psi I also have a boost gadge on it and it still did this when I wasn't under boost.

where is the boost gauge tapped in?

I would put it in the line to the waste gate and check it there.

 

I can not imagine being at 4k RPM and not having any boost

as you say.

 

Do as you wish but I would take a look at the wastegate

and it's plumbing.

 

What you describe is classic fuel cut feel.

Update:

 

 

Well I finally found my problem, it turned out to be a Post Turbo Boost Leak

 

 

The tube from my intercooler to the TB had a slight tear in it leaking boost

 

Fixed the leak and all is well now!

 

Back to kickin rump roast!

That is certainly good to hear. My GL-10 did something similar to that to me once. I had downshifted to pass a slow moving vehicle and all of a sudden there is a big whooosh sound(which is never good)and it feels as though the car has no power. So I pulled over to see what the heck the deal was. No sooner do I pop the hood, steam and coolant starts coming from what appeared to be the intake manifold. So I got kinda irritated and started trying to locate the source. Well, come to find out one of the age old coolant lines that run underneath the manifold had split and gotten about a 1/16" hole in it. Luckily I wasn't far from home, and there was plenty of coolant in the radiator and overflow tank, so I was able to limp it home and fix it. I replaced it and all the other little hoses that same night to safeguard against a repeat of this event.