I have a problem that seems weird to me. If I'm in 4th or 5th gear and floor it, it will build up about 5 psi then stop for a second then finish building up to 10 psi. It's like it runs out of breath and needs to take a break and then start again. What is weird is that it accelerates very smooth in 1st through 3rd. No hesitation at all. Any ideas or things to look for?

hows the a/f ratio when it happens? could be too rich at that point

Being rich could bog you down......like me. But hey, I'd rather be rich than lean.

I'll pay a lot better attention on the way home. I'm pretty sure it's like .96 though which isn't real rich. It gets about .88-.91 at 10 psi. But why would I hit a rich spot only in 4th and 5th gear?

Are you using some type of boost contoller? Maybe its sticking or malfunctioning, causing the wastegate to open prematurely...Just a thought..Check for boost leaks too..and vac line leaks..

Well I have a simple homemade bleed valve on the WG vac line but it's not bleeding anything because the spring is 10psi. I really don't think it's a boost leak. Trust me I know how they feel because it took me like 2 weeks to get rid of them all :p I do have a vac leak sometimes that I can't find. My idle will just drop to 10 hg for a bit and then come back up like nothing happened. I don't know what's up w/ that???

hey since some of you guy's have had boost leakes how do you know if you do? I ask because sometimes my car wont hit full boost till 4-4500 rpm then other times it's on tap at 3500-4000. what should i be looking for?

What I did was take a spray bottle of soapy water and w/ the car running spray down a connection spot and rev the engine. If it bubbles you have a leak. There are other ways but this is just a quick test. I think you can take the IC pipe off from the compressor side and cover it w/ cardboard and the car should die from lack of air. If it runs you have a leak. Don't quote me on the second one because I've never tried it.

Any more ideas on my problem? Do you think it could be fuel related?

I believe it does sound like a fuel problem. In 4th or 5th gear, you have less torque, and due to the gear ratio at those gears, it's going to take more time to build up the rpm's. Since you're seeing .96V, that's rich enough to cause the car to bog down a bit. Because of the gear ratio and lack of torque in the higher gears, the ecu might not be able to adjust the fuel curve fast enough (in 4th and 5th).

If you try to accelerate from, say 4500 rpm to 5000 rpm, does the car still hesitate? If it does, you might be experiencing fuel cut. However, I think it's the ecu not knowing what to do with that excess fuel. Also, do you have any kind of fuel control, i.e., an AFC? If you did, you could try to out the fuel curve a little. I know this isn't very scientific, but this is similar to what I experienced in the past.

Nope, no fuel controllers. Everytime I've done it it's been from a pretty low RPM (2500-3000) I will experiment tomorrow on the way to work and try from a high RPM and see what the a/f is and if it bogs. Thanks for the help so far guys.

Well I got on it at ~4K in 4th gear and it just pulled w/ out hesitation. So it's only doing it in high gears when it has to build up boost.

Sounds like fuel to me, or lack there of.

That sounds almost like you're running rich. Unfortunately, without any for of fuel controller to lean out the fuel system, it's going to keep doing that. It's better than running lean, right? Or, you could try to lower the WOT (under boost) fuel pressure a tad bit. That might help. What kind of FPR do you have?

I have the Vortech SFMU. I've never messed w/ the "boost" screw or anyhting though.

If it won't hurt anything then I'll just let it annoy me. I'm going to see how fast I can get the car w/ stock ECU and #30's so I won't be getting an AFC anytime soon.

What about FCD? Are you using anything to block the MAP sensor from seeing boost? (The options I know of are HRC FCD, Vortech VC1 & VC2, and MissingLink check valve.)

My HRC FCD hesitates a LOT when transitioning into a full boost situation. It feels like the MAP is lazy and doesn't report in to the ecu until a second or two of mashing the throttle. Datalog/watch your MAP voltage and your O2, and post it here.

I have a VC-2, no datalogger, and no money to buy one ;)