boost slowly reaches 10 pounds..

[stevieapollo]

It seems when i go into boost i start at 6 or seven pounds then my boost gauge makes its way up to 9 or 10 pounds.... I thought the case was usually you start out hight then your boost tapers down. its almost the opposite for me i start lower then work my way up.. Could this be a problem with me building pressure?

 

When i go into boost i look at my boost gauge and it will say 6 pounds then as the rpms rise ill see the boost gauge work its way up to 10 pounds. is this normal? It almost seems like this only happens most of the time. sometimes i will look down right when i go into boost and ill see my gauge at 10 pounds, it feels good when this happens but its just not always the case. any thoughts?

 

*apollo*

[JoeyLeet2]

Is the car stock? Clogged cats or weak accordion hose?

[ad8tsi]

could be that your waste gate actuator is going bad.

has a test pull the vac lines off the wga and cap them.

take a drive and boost it. control boost with your foot

and watch a non-stock gauge so you don't over boost.

if boost still builds slowly you have a restriction to

either intake or exhaust flow.

[Indiana]

Never run the car without the wastegate reference hose connected unless you want uncontroller max boost from how many ever revs that turbo can spin so you might end up with 40psi before that wastegate opens if it opens at all so you want to blow your headgasket or melt pistons leave the hose off. The hose is not vacuum, its boost pressure there is no vacuum at all related to a stock wastegate actuator. Boost pressure is what opens the wastegate as the boost overcomes the spring in the actuator and the arm from the actuator is extended and pushes on the flapper arm and that is just a lever attached to a little round door that lets the exahust out, its called the wastegate. When exhaust goes out the wastegate it isn't going out the turbine blades in a great enough quanity so that's where there is no boost when the wastegate is open. At least little to no boost that is. If the arm feel off the pin and the wastegate is fully open you may only get a couple psi boost at high rpms. No hose, wastegate never opens. I've never seen a bad wastegate actuator has anyone else? How did it go bad, you set fire to it?

[mikec]

What model year is the car? The 88-later cars, with 5-speed trannies, run a low boost (approx 7.5psi but it can vary +/- 2psi) until the RPMs reach 4000; then it'll quickly jump to around 10.5psi (+/-2 psi again). That's intentional. Auto tranny cars should boost to 10.5psi regardless of RPMs.

 

Slow/laggy boost typically means:

* turbo is "tight" - i.e. hard to spin. On a cold engine, undo the accordion hose going to turbo inlet. Grab the little nut on the turbo shaft and try to spin it. It should turn fairly easily and smoothly. If it has sticky spots or a lumpy feeling the guts of the turbo are cruddy (typically "coked" oil) and it needs to be disassembled, cleaned, and rebuilt.

* tubine wheel on turbo is worn, or the exhaust housing is worn allowing too much exhaust to bypass the wheel rather than spinning it.

* sloppy/loose wastegate, letting exhaust leak around the turbine wheel instead of spinning turbine wheel

* leaking exhaust manifold gasket (got black soot marks on the heat shields or body firewall?)

* leaking turbo to exhaust manifold gasket

 

mike c.

[ad8tsi]

in response to indy's questions: yes, I have seen a bad wga and no, I didn't set fire to it.

symptoms include inconsistent boost levels and inability to reach boost beyond 5 or 6 psi.

I've never opened one up but it doesn't take much imagination to understand there is a sealed

diaphram that over time can leak. will wonders never cease?

 

vacuum line / boost line: are you serious?

[Indiana]

I look at many different things one piece at a time, deal with them when I get a chance and are forced to deal with them when I must. The wastegate actuator no I have never cut one open. Most all of these cars are modded and many hoses are missing, leaking or connected wrong. For 1983 there is a difference in the system and the turbo. The 83 TC05 turbo isn't water cooled, nor were the early 84s. The factory did have a kit to swap the cartridges out for the water cooled TD05 cartridge. There are slightly different actuators for early cars Vs. 88/89 cars. The 83 actuator, if the description is correct and I know there are errors in factory service manauls and I've never heard this before but very few have a fully working stock setup on their 1983 cars. The wastegate on the 83s does get a vacuum on it when the coolant is cold, this is when the thermo valve allows this and its only when the motor is cold so the turbo can't make full boost when the coolant is cold. This is described for a 1983 model only. The 1984-1987 cars have a single port actuator that work much like the 88/89 system but without the "safety" margins and the max boost setting is a bit lower. The 88/89 cars have a three port actuator and differences in the ignition ignitor. When the 02 sensor isn't seeing premium fuel there is a solenoid valve that will limit boost providing all that is connected and working, it will "limit" boost but it doesn't say to what level. The lower end of the three port actuator should be ~8psi. This is also the case for a manual transmission car if the rpms are below 4000roms to keep the lower gears from being slammed from full boost -most remove all this and there is no lower boost limits for lower rpms or for cheap gas.

 

 

The hose to the actuator comes from one of the intercooler pipes, there isn't ever any vacuum in the intercooler plumbing. The positive boost pressure from that plumbing is what is connected to the actuator by that reference hose. It may be called a "vacuum" hose only in name but it never sees vacuum, ever unless its a stock working 83 system which there are but a handful and I know the one 83 I drive that system is intack but I never checked it and on the other 83s its all been removed. I also remove all the "safety" system if you will that limits the boost at lower rpms in manual trannys cars and I only run premium fuel. The 87 I know you can run cheap gas and I can't remember but I didn't think that 87s had a 3 port actuator. 88/89 fuel systems you could run cheap gas and you would have lower max boost as a result IF the stock system was all in tact and functioning.

 

So, if an actuator is "bad" that means that either the spring inside is busted, and how did that happen OR its the diaphragm that is leaking. In regards to not making boost a leaking diaphragm won't let boost build to push against the spring that is holding the arm in. Its the extension of that arm that opens the wastegate and that is only going to happen when boost pressure acts upon it. Apply all the vacuum you like to an actuator and it won't do anything at all (unless you have an 83 actuator). The range of movement of the arm on these actuators is about 1/4" and that just barely lets the wastegate flapper open. If you have some boost limiting or strange boost levels that are low then its very possible on an older car that there is something physically holding the flapper open. It might be a piece of carbon, a piece of a valve seal or a piece of a broken jet valve or a piece of a broken spark plug who is to say. If you removed the actuator and this was going on, after the actuator is off that flapper arm can move WAY back, if anything was in there at that time it would fall out. If the arm was not connected at all I know that modded cars can still make about 5psi boost its happened to us more than once. A stock setup wouldn't do that. Its much more likely that the actuator you had was adjusted wrong, it did not have enough preload on the flapper or at rest it was actually holding it from seating. The actuator does have a resting position and you can slip that arm over the flapper and unless its pulling against it to keep it closed you'll not get full boost and it may vary. Manual boost controllers. I hate them they are pieces of crap. Engine bay temperatures effect them, they won't react the same way two times in a row but for most people and what they want form them they will work. The do not act like solenoid valves. The stock system has the chamber filling with pressure trying to move the arm out to reduce boost, MBC can limit this effect but blocking some of the boost and EBC remove it all. An EBC won't pass boost pressure to the actuator until the set level is reached so there is no loading of the actuator chamber and this can also have a nice side effect of slight boost spike on each shift from the time it takes the boost pressure to pass through the valve and fill the chamber. The tests for a "bad" actuator are all about if it CAN'T let the wastegate open, not that it does and shouldn't.

 

This is a 1983 ONLY description.

http://photos-e.ak.fbcdn.net/hphotos-ak-snc1/hs215.snc1/8220_1052066480085_1778479606_104158_5734002_n.jpg

 

What does the first sentence of that description say? Its says it is there so the boost can't EXCEED the specs, not cause it to be lowered. If its lowered then the actuator isn't the problem. It may seem like it was the problem and the one you put on was actually just shorter so it loaded up the flapper and allowed higher boost to be made.

 

So, where's the part about ceased wonders in this?

------------

"I've never opened one up but it doesn't take much imagination to understand there is a sealed

diaphram that over time can leak. will wonders never cease?

 

vacuum line / boost line: are you serious? "

------------

Ya, I'm serious. Same is assumed about the vacuum advance unit, it advanaces timing for vacuum and then retards timing when under boost. Its when those diaphragms are leaking you have problems. The motor knocks, the ignitor then instantly pulls back timing to save the motor and the car jerks and bucks just about the time you were feeling good.

 

http://www.b2600turbo.com/images/diagramvacadvance.jpg

Edited October 22, 2009 by Indiana

[nycain]

had the same issue just solved it , i changed the clips the vaccum advanced and the secondary injector car runs like crazy my car 88 auto

[stevieapollo]

whats the best way to check the vac advance where did you get ur replacement?

[Indiana]

autoparts stores have them, may have to be ordered. they also sell a hand vac. pump with a gauge I think its brand name is "mighty pump" or something like that.