gutted CAT boost question

[foregn2]

Will a gutted CAT require adjusting boost level down. Seem like my boost has increased and picks up alot faster to the point the car seemed like it was going to over boost and a let out and black smoke shot out the black. Also and WOT kcock gauge goes into RED and turbo makes noise and car hesitates. Any help

 

[fitz3820]

In short, yes with a better flowing exhaust you will increase boost levels.

It doesn't seem that you have a boost gauge in the car, I would recommend one ASAP.

You are getting into some serious knock and need to pull the boost back before you lose a head gasket or do some serious damage to the car.

The black smoke extra fuel being added and the hesitation is the ECM pulling timing trying to prevent you from breaking the engine. The noise you are hearing probably isn't the turbo but detonation - you are basicly beating the crap out of the motor under detonation, it won't last long under those conditions.

 

[foregn2]

In short, yes with a better flowing exhaust you will increase boost levels.

It doesn't seem that you have a boost gauge in the car, I would recommend one ASAP.

You are getting into some serious knock and need to pull the boost back before you lose a head gasket or do some serious damage to the car.

The black smoke extra fuel being added and the hesitation is the ECM pulling timing trying to prevent you from breaking the engine. The noise you are hearing probably isn't the turbo but detonation - you are basicly beating the crap out of the motor under detonation, it won't last long under those conditions.

Thanks for the info. I have a boost gauge and boost went to about 20lbs instantly at WOT. I figured you said about boost , but wanted to be for sure. Will adjust boost back down immediately.

 

[henschman]

ok, i'm definately getting rid of my cat now!

 

[VadersV6]

Dude, was that 20psi on pump gas? Better start a new engine fund. Youve probably already torn up your bearings. Better hope the black smoke is truly black and not dark blue....you couldve blown a ring land off and killed some rings. Boost in the wrong hands is like a gun in the wrong hands. Something's gunna get hurt.
Get together a system of tuning yourself (extender/LS1 translator, bigger injectors/LS1 MAF), and get an alky kit. Learn how to tune without the alky first, for 16-17psi, then do the alky and tune that. Learn to take detonation very seriously. Some people like to tune for a couple degrees of knock retard, but my car will make a popping marble sound before the knock sensor even starts to pick something up. So assuming the knock sensor isnt picking up anything, I tune for O2 volts and engine sound. Tuning with KR alone isnt very reliable and can end with your rotating asembly fitting into a coffee can.

 

[bison]

Dude, was that 20psi on pump gas? Better start a new engine fund. Youve probably already torn up your bearings. Better hope the black smoke is truly black and not dark blue....you couldve blown a ring land off and killed some rings. Boost in the wrong hands is like a gun in the wrong hands. Something's gunna get hurt.
Get together a system of tuning yourself (extender/LS1 translator, bigger injectors/LS1 MAF), and get an alky kit. Learn how to tune without the alky first, for 16-17psi, then do the alky and tune that. Learn to take detonation very seriously. Some people like to tune for a couple degrees of knock retard, but my car will make a popping marble sound before the knock sensor even starts to pick something up. So assuming the knock sensor isnt picking up anything, I tune for O2 volts and engine sound. Tuning with KR alone isnt very reliable and can end with your rotating asembly fitting into a coffee can.

Hopefully that thing is stock or nearly stock. Less damage if thats the case. Whenever doing any mod that frees up exhaust restriction you have to adjust down the boost and ease into it, then begin to increase boost again slowly. Sometimes the wastegate hole will need to be opened up some. I remember the first time i punched out the cat on my old GN 12 years ago. It was a night and day difference as far as spool rate was concerned. A new fuel pump will be needed if not already in place. Good luck.

 

[bison]

ok, i'm definately getting rid of my cat now!

Get a fuel pump and adjustable fp regulator first!

 

[gnx7]

pump gas timing chip and pump gas 91/92 limit your boost to 15/16psi in summer... winter can sometimes tolerate 1-2 more psi.

If not... you will be detonating even if it isn't audible. If it is audible that is already a horrible thing as that is MAJOR detonation.

 

[foregn2]

Dude, was that 20psi on pump gas? Better start a new engine fund. Youve probably already torn up your bearings. Better hope the black smoke is truly black and not dark blue....you couldve blown a ring land off and killed some rings. Boost in the wrong hands is like a gun in the wrong hands. Something's gunna get hurt.
Get together a system of tuning yourself (extender/LS1 translator, bigger injectors/LS1 MAF), and get an alky kit. Learn how to tune without the alky first, for 16-17psi, then do the alky and tune that. Learn to take detonation very seriously. Some people like to tune for a couple degrees of knock retard, but my car will make a popping marble sound before the knock sensor even starts to pick something up. So assuming the knock sensor isnt picking up anything, I tune for O2 volts and engine sound. Tuning with KR alone isnt very reliable and can end with your rotating asembly fitting into a coffee can.

Yeah on 93 pump gas, thats why i got worried. car is pretty much stock except for the things in my signature. Before I gutted the CAT i didnt have these problems. I keep adjusting the wastegate almost to the point where it is past the hookup and I'm still jupm up to 18-19 lbs of boost.

What next?

 

[foregn2]

Hopefully that thing is stock or nearly stock. Less damage if thats the case. Whenever doing any mod that frees up exhaust restriction you have to adjust down the boost and ease into it, then begin to increase boost again slowly. Sometimes the wastegate hole will need to be opened up some. I remember the first time i punched out the cat on my old GN 12 years ago. It was a night and day difference as far as spool rate was concerned. A new fuel pump will be needed if not already in place. Good luck.

Have RED XP pump. Yeah this gutted CAT thing is a big DIFFERENCE.

 

[bison]

Yeah on 93 pump gas, thats why i got worried. car is pretty much stock except for the things in my signature. Before I gutted the CAT i didnt have these problems. I keep adjusting the wastegate almost to the point where it is past the hookup and I'm still jupm up to 18-19 lbs of boost.

What next?

What chip do you have in there? Test wastegate hoses and actuator for pressure leaks. Any perforations in any of the hoses between the compressor, solenoid, and actuator will cause an increase in boost. If it has the original hoses their toast. Replace them ASAP and dont drive hard until you get the boost down! Wastegate actuator diaphragm could have holes in it also causing overboost.

 

[foregn2]

What chip do you have in there? Test wastegate hoses and actuator for pressure leaks. Any perforations in any of the hoses between the compressor, solenoid, and actuator will cause an increase in boost. If it has the original hoses their toast. Replace them ASAP and dont drive hard until you get the boost down! Wastegate actuator diaphragm could have holes in it also causing overboost.

RA 93 chip

 

[foregn2]

What chip do you have in there? Test wastegate hoses and actuator for pressure leaks. Any perforations in any of the hoses between the compressor, solenoid, and actuator will cause an increase in boost. If it has the original hoses their toast. Replace them ASAP and dont drive hard until you get the boost down! Wastegate actuator diaphragm could have holes in it also causing overboost.

Kind of new to this but a how do I test for pressure leaks?

 

[Paul Clark]

Get a Mighty-Vac hand operated vacuum pump/tester.
They're great for checking both engine vacuum and possible leaks.
Wondering how you're getting that much boost with a stock wastegate setup and the rod being backed off.
Sure it's not a HD unit?

 

[bison]

Wondering how you're getting that much boost with a stock wastegate setup and the rod being backed off.
Sure it's not a HD unit?

Thats what i was wondering. Boost leaks are the more likely suspect. The mighty vac works well or you could check for big leaks by sucking on the hose and sealing the hose end with your tongue.

 

[foregn2]

Get a Mighty-Vac hand operated vacuum pump/tester.
They're great for checking both engine vacuum and possible leaks.
Wondering how you're getting that much boost with a stock wastegate setup and the rod being backed off.
Sure it's not a HD unit?

I have a adjustable wastegate. Just found why boost levels were possibly high. Found a hose was loose by the turbo dont know which one or what it is but its was off . Going to connect and see if that helps.

 

[fitz3820]

When you test, don't just punch it and see if it still goes to 20psi!!!!

Find a nice open stretch of road and ease into the boost - you really need to get it down below 14-15 psi at least on pump gas.

You might want to get a new set of vacuum lines that control the boost - goes from the turbo to the wastgate actuator and the wastegate solenoid.

Most vendors will carry it.

 

[VadersV6]

When you test, don't just punch it and see if it still goes to 20psi!!!!

Find a nice open stretch of road and ease into the boost - you really need to get it down below 14-15 psi at least on pump gas.

You might want to get a new set of vacuum lines that control the boost - goes from the turbo to the wastgate actuator and the wastegate solenoid.

Most vendors will carry it.

Alot of multi-owner TR's will have the vacuum line system all screwed up and hosed wrong. You should get a vacuum line chart and make sure everything is right. The wastegate may be plumbed up wrong.

 

[foregn2]

When you test, don't just punch it and see if it still goes to 20psi!!!!

Find a nice open stretch of road and ease into the boost - you really need to get it down below 14-15 psi at least on pump gas.

You might want to get a new set of vacuum lines that control the boost - goes from the turbo to the wastgate actuator and the wastegate solenoid.

Most vendors will carry it.

Thanks, I'm good now. Got a long stretch boost stayed at 15lbs no knock. I had it about 16-17 lbs before no problem. May just work my way back to 16lbs.