pnoob2

hello, just put in a full BB header and exhaust combo...now im getting considerable bogging under boost. however after it bogs for a second or so the boost begins to build and runs fine again....this process repeats itself over and over and i was able to replicate the problem in second gear and up but not really in first.. My mechanic said it might be a faulty diverter valve...so we are putting in a 996tt diverter valve in it for a stiffer spring rate. any ideas???? I also have a 1 bar spring in the car....everything else is bone stock. Feed back welcomed

pnoob2

just tried the 996tt diverter valve...still the same problems ...bogging ....its easier to bog when trying to boost with low load...like starting off in second gear or third.

pnoob2

I think the headers may be leaking........=(

Staffan

Is it like a fuel cut off?

If so, it's most probably the pressure switch in the intercooler that is activated due to high boost.

Edit:
Read my post below on what to do now.

Staffan

The pressure switch cuts the fuel when the pressure in the intercooler reaches a specific boost level.

Reasons for the pressure switch would activate now:

1. Faster turbo spool due to shorter headers and less back pressure in the exahaust creating a pressure spike in the intercooler
2. Boost creep, meaning your headers can't evacuate enough exhaust through the waste gate (common B&B problem)
3. Problems with the waste gate

Next step
1. I would start by checking the wastegate plumbing and make sure the waste gate opens properly
2. Ground the pressure switch and logg the boost

Don't worry, I've been there, so has many on this forum.
Depending on the outcome of your tests there are several options, but I can tell you one thing, don't run away and buy a new wastegate (at least not yet), a common suggestion that in many cases is a waste of money IMO.

Staffan

Why do you think that?

tjr

From my own and a friend's experience, some B&B headers seem to leak a bit when the engine is cold - you'll hear a ticking on start-up that goes way once the engine is warm.

fritz k.

i have had a similar effect two years ago.
turned out that one of the pressure hose clamps were in place, but not tightend. that may cause the pulsing boost.

fritz

pnoob2

How do i check the plumbing in my wastegates?

Staffan

Could you elaborate on what you mean by "bogging", how does it behave.
The fuel cut is pretty harsh, not like a rev limiter.

About the wastegate, it has two air ports, top and bottom.
The top one should vent to air and the bottom one should be connected to the intercooler.

The top one is a thin steel pipe, make sure it vents to air, not plugged and no connected to anything. It vents behind a metal cover.

The bottom port is connected to a small steel pipe, this pipe is connected to a rubber hose that goes to the intercooler (left side). If this rubber hose is pinched the wastegate won't open.

Staffan

Good call.
I think I misunderstood the "bogging".
When installing the B&B headers the turbo had to come off.
Could be the hose going into or more likely the hose going out from the turbo.

pnoob2

well this is what i have gathered so far....when i say bogging i mean the boost when it is building flutuates on /off on/off ... also I noticed the car is running rich the tips on both the exhaust and wastegate ends are black from fuel. The car is so rich that today ...(hot day 90degrees) it bogged out at idle and died. I did no tuning to this car ...however the previous owner put in a 1 bar spring and im sure had to turn up the fuel to compensate for that added boost....ever since then besides putting on headers and exhaust no tuning has been performed.

pnoob2

I will have my mechanic check the waste gate plumbing and all the pressure hoses to make sure they are tightened in the meantime....then if all else fails we will retune the A/F ratio

pnoob2

Staffan, I was reading your previous post about the pressure switch, I dont think its cutting fuel...although it feels like the same symptom, but my car is clearly running too rich to have fuel cuttoff...even at idle today it bogged out...and I do notice that when the car does bog under boost it is dumping black smoke ...another sign of running rich

pnoob2

these cars are sure temperamental ...