silverbullet

Hi,
My car has a Accuboost with cv delete, with a Vitesse chip set. The problem is that I can't get over 15 psi. I can get 15 in third gear sometimes, and in 4th and 5th usually. Sometimes it will show 15 from 3rd gear on up. Then on other occasions boost will be lower (12-14) in the same gears. I expect the usual drop off at high rpms, but should'nt a k26 be able to make at least 17psi?
I don't think I even get boost in first gear at all. When set at a specific boost level, each gear should produce about the same amount correct?
I was thinking that it might be the unshimmed, stock wastegate. I don't think that I have a vac leak, as it has a strong vacumn and does boost to 15psi sometimes. Can a stock wastegate hold more than that? All ideas greatly appreciated!!!
Thanks,
Josh

NZ951

I say wastegate... they are junk. Compared to modern Tial units and so on.

silverbullet

Alright,
Just went out with the wastegate hose clamped shut. Still only got 15psi. That would mean the problem is making boost, not just holding it. Like a small leak somewhere that gives way at around 15psi, making it hard to find. Would hooking an air compresser up to the banjo bolt and setting it to around 18psi work? That way maybe I could find to leak better. God I hate boost issues!
Thanks

special tool

No, its your wastegate. I am surprised you can get 15 at all.
The exhaust pressure alone will push the valve out, it doesn't need the signal.

azmi951

different weather conditions require differnet settings on the mechanical boost controler to achieve a set boost level.
In terms of electronic boost controling what you are doing now is setting a duty cycle and as a result of a duty cycle you get a boost level. Electronic controlers set a level and then determine a duty cycle to achieve this.

fast951

- I would pressure check the ciomplete intake system
- Check for leaks in the exhaust before the turbo (tough one)
- Check the turbo for any play or damage to the compressor wheel
- shim the WG 4-5mm washers will do wonder.

silverbullet

But wouldn't the car normally boost way high when you disconnect the hose that goes to the wastegate? I basically blocked it where the banjo bolt is via a bolt and hose clamp. How should I pressure test the system?
Thanks guys

special tool

It wll boost to whatever the wastegate spring will hold - against exhaust (only) pressure.
If you take it off and shim it 4-5mm you will hold a little more.

silverbullet

Yay, an excuse to buy a new wastegate! I will order a 38mm Tial as soon as possible. Thanks for helping me understand this stuff!
Josh

NZ951

www.speedforceracing.com or MySwiss for the Tial units

Gator_86_951

You'll need an exhaust shop to help you with the install since your car is an 86.

NZ951

Thats the thought, but I ave heard of buys with an 86 and it fitting fine... I just got the muffler shop to weld in some new pipe for $50.

Gator_86_951

is the tial dual port?

NZ951

All Tial are homy.