Overboosting Problem

Sean Krupa

Sean Krupa

Moderator
I have been trying to solve my overboost problem. I unplugged the wastegate solenoid to see if it gets 8-11psi and it's going up to 15psi. I have turned the wastegate out 4 turns and it barely got any better.

I have done the following mods this winter, Bellmouthed Inlet of turbo, Bellmouthed Outlet of turbo, Ported the mismatch to exhaust manifold, ported the wastegate a little. I installed a Muffler Delete pipe. I STILL have a CAT. I have a 3" ATR exhaust also.

What could possibly be the reason why I'm overboosting looking at Datamaster, and should I keep loosening the wastegate until I get 8-11 with the solenoid unplugged?
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: Overboosting Problem

Do you have a test pipe or high flow cat installed. Mine crept upto 13-4psi with a high flow cat and the solenoid unplugged.
 
Sean Krupa

Sean Krupa

Moderator
Re: Overboosting Problem

I have a Stock Chip with a ATR replacement cat, not High Flow. I also have new vaccum lines.

Thanks,
 
syclone rider

syclone rider

New member
Re: Overboosting Problem

Im having the same problem with it unplugged im at 12.But with it plugged it was overboosting and busting up.But i have no cat.
 
dalwine250

dalwine250

Donating Member
Re: Overboosting Problem

check for a sticking wastegate when its hot . i went thru the same issue after gutting my cat.the stock wastegate is too small for a free flowing exhaust.i opened mine up,knocked out the plug,cut out the bridge and made the DP fit the big flange (JSM flange). solid boost control ever since
 
Mtn Z

Mtn Z

Donating Member
Re: Overboosting Problem

I have the same issue as well. 14 psi with the solenoid unplugged and overboost with it plugged in. This is with no muffler and the stock cat.
 
syclone rider

syclone rider

New member
Re: Overboosting Problem

dalwine250 said:
check for a sticking wastegate when its hot . i went thru the same issue after gutting my cat.the stock wastegate is too small for a free flowing exhaust.i opened mine up,knocked out the plug,cut out the bridge and made the DP fit the big flange (JSM flange). solid boost control ever since
Click to expand...
Pics if you have them please.
 
Sean Krupa

Sean Krupa

Moderator
Re: Overboosting Problem

I have checked the wastegate, and it was NOT Sticky, moves Freely after a Datamaster run.
 
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dalwine250

dalwine250

Donating Member
Re: Overboosting Problem

sorry i lost the pics when my old lappy died . there are pics on here somewhere of simular porting
 
Sean Krupa

Sean Krupa

Moderator
Re: Overboosting Problem

I have been using Datamaster while my dad is driving and I'm looking at the screen, so we have an accurate reading of boost, even though I have an aftermarket boost gauge.

Could my overboost be a cause of a bad wastegate actuator?

Sure I would love to have a JSM downpipe and cut off the back of the turbo, but funds aren't cooperating at the moment and would like to get things running right in stock form.

Thanks for all the suggestions,
 
Sean Krupa

Sean Krupa

Moderator
Re: Overboosting Problem

Update,

I bypassed the wastegate solenoid by just putting vaccum line from the compressor to the actuator. It barely made a difference in how much boost I can build. I also turned the wastegate out another 2 turns (Total of 6 turns) and now the boost is at 10psi.

The wastegate actuator seems to be working fine being that I tested it with an air compressor and it moves freely. The setting I have now on the wastegate is that it's slightly open and its still making alot of boost.

I'm going to try and install my ATR 3" muffler back on to see if it makes a difference even though it's a straight through design.

I'm wondering if the porting of the mismatch to exhaust manifold is making it overboost? Also, I have 2 turns left on the wastegate rod before the rod end comes off. My dad said that he has never had any boost problems before all the porting/muffler delete. The truck runs Great with no other problems beside the overboost and slight knock between shift points.

Keep the suggestions coming, I appreciate it:tup:
 
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sharkbait

sharkbait

New member
Re: Overboosting Problem

everything ive read regarding overboost indicates that opening up the exhaust on a stock turbo/wg using anything but a JSM style will result in overboosting. it kinda makes sense because the exhaust side of the housing is restrictive where the wg puck is. thats why unshrouding the wg puck and using a JSM style dp work. just my .2
 
Sean Krupa

Sean Krupa

Moderator
Re: Overboosting Problem

Here are some pics of the Porting I did to the Turbo,
TurboBellmouthInlet.jpg

TurboBellmouthOutlet.jpg

TurboPortWastegate.jpg


Could all the porting of the Turbo be causing Overboost?
 
sharkbait

sharkbait

New member
Re: Overboosting Problem

im thinking porting the wg wouldn't be a bad idea, since you don't have the cash for a JSM dp right now.
 
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