Popping Then Loose Boost

[Brian Verson]

I have a strange concern with my motor . I just added a TA49 turbo and I can't get it dialed in like it was with the stock turbo.
It doesn't matter what boost or timing level I'm at it still does it , not as much with lower setting but it still does it.
Its feels like a miss when running at around 3500 rpm and up
and my boost is all over the place. It jumps back and forth. When I'm running 20psi of boost and it feels like it misses. The boost level will drop to 14/15 psi of boost and then recover . The engine was rebuild about 20K miles ago by the original owner .
Could the valve springs be my problem not allowing the engine to build or hold boost at a certian RPM, or is it something else?



TA49 , SMC , 3"ss ATR dp Single Shot , V-Booster , FMIC , Adj. Wastegate , BLA BLA BLA .
My best run 13.57et / 106.98 mph no midrange power .

 

[UNGN]

What injectors are you running?

 

[GN-231]

Check for exhaust leaks around the turbo flange and stuff. 20 psi seems like a lot of boost, did you start low on your boost and tune your way up to 20 psi??? The 49 flows a lot more air than the stocker at set boost levels so you might have better luck running a lower boost than you used to with your stock turbo. You might be fine with the 20 if you are using your SMC though.

 

[Sleeper]

Are you running any type of scan tool? Are you getting any knock ? What are your O2 #s?, Any additional info would be helpfull
Off the top of my head... I would guess bad coil pack/module

Paul

 

[Snappy6]

I am running 40lbs inj.
I will check for exhaust leaks and all the bolts to make sure they are tight .
I have a snap-on scanner my o2 mv is around 800/850mv at WOT some times it jumps to 900mv but not offen . I've tried playing with fuel pressure , boost levels , and timing setting but it doesn't help. My TPS is 4.53v at WOT , Coolant temp is around 170 / 190 depending how long is sit in the staging lanes.

I have replaced the coil pack , MSD wires , and Plugs AC43TS .350gap and had no change . Installed a Heated O2 sensor from Kirban ( Which I Highly Recomend ) .

Thanks Brian

 

[Sleeper]

Just throwing stuff out there... Does it feel like wastegate flutter? Is it the stock puck or OS?
Since you are pushing a lot of air you may be having MAF drop outs. Whose chip are you using?
Any knock?

Paul

 

[kevans]

Just for more input...I had the same problem and it turned out to be the wastegate solenoid. Tried...new ones...known good ones...everything. Eventually I just bypassed the solenoid and had the command taken out of the chip. Works great.

Also if you are running a stock MAF sensor you could get an "overload" to the MAF at certain boost levels and that has to be dealt with. LS1 MAF sensor cured that problem for me.

Kev

 

[Snappy6]

I'm using the Casper Electronics 7 pos. Chip .
I have a 3"ss ATR downpipe w/the over size puck . But I,m not really sure what what wastegate flutter feels like?
I know a lot of people that are using the stock MAF sensor with this turbo and don't have this problem . I will hook my lab scope scan tool to it and check voltage at the sensor under load to see if I have any dropouts in voltage .
I will also bypass the wastegate solenoid and try it that way.

Thanks Guys Brian

 

[Snappy6]

I'm thinking it might be wastegate fluter . I was talking with a Mike Christman A GN GOD out of St. Louis . He was saying the the hole in the exhaust housing for the waste gate needs to be 1" 400 thousands mine is .920" of and inch my puck is 1" 500 thousands .
The stock turbo housing is the same as this one . If I'm am moving more air should there be a bigger hole for the exhaust to escape through ?

 

[UNGN]

To small a wastegate hole would cause overboost, not a drop off in boost.

The only way overboost would cause your boost to drop is if you got Knock, and timing retard. This would show up on your scan tool, Right? You are using something that is monitoring knock, right?

More than likely your puck is sticking open. This appears to be very common on ATR TH style downpipes. You are like the 23 person this happened to on this BB alone. The Fall of 2000 is when this started cropping up big time. Take your rod off and make sure the arm moves freely. Get it up to operating temperature and see if it still moves freely (use pliers). Because this has happened so many times in the past, I would suspect it first.

Whatever you do, DON'T port your wastegate hole, yet. Porting your waste gate out to 1.4" and the 20 psi boost won't drop to 14 psi, it WILL be 14 psi and you'll have to crank in 5 or 6 arm revolutions to get back to 20 psi. This extra force you will crank into the actuator will create extra bind and the sticky puck is more likely to stick open. problem not solved.

ATR is aware of the problems in the past and if your DP has not been repaired by them, it may need to be.

 

[Snappy6]

Thanks UNGN I will call ATR in the morning and ask about this .
I checked the rod cold but not hot seems like it moves freely at this point.
It didn't do this with the stock turbo and .83 EH does the TA49 make that much difference .

 

[Snappy6]

Boost Surge And Popping

UNGN :
Thank you for all your help . I called ATR and they knew just what was wrong. They told me to install a manual bleed valve instead of using the ECM and wastegate solenoid . They sent me the bleed valve and it fixed me right up.

Thanks again Brian Verson (Snappy 6)

 

[UNGN]

Good deal.

That makes sense. If the puck is a little sticky it may hang when the solenoid is cycling. A bleed valve doesn't cycle the wastegate. No cycle, no stick.

When going to chips like a max effort, you don't use the solenoid anyway. In the future, if you go to an electronic boost controller, the problem may crop up again (or the puck might work itself loose, by then, too, so you may be fine.)

 

[rastaz]

Can someone explain this bleed valve a bit more? How does it work and install? Do you need to have your chip modified?

TIA

 

[UNGN]

First, here's how the stock car works:

When the wastegate solenoid is open, no boost pressure is being directed to the wastegate actuator and the turbo will make boost until the motor blows.

If the wastegate solenoid closes, boost is contained in the "Y" hose and when it reaches a certain level, it overcomes the spring pressure of the wastegate actuator and opens the puck.

The computer chip electronically controlls the solenoid and can "cycle" the solenoid if programmed to do so to provide increased boost from a pure solenoid closed position.

A bleeder set up bypasses the solenoid and uses a bleeder valve instead of the electronic solenoid. Similar to a pressure regulator, the bleed valve will bleed off boost until a certain point at which boost is directed to the the actuator to open it.

If you keep your stock solenoid plugged in, but bypass the hose, the computer will never know you are using a bleed valve.

 

[Snappy6]

UNGN is right on the money !!! And it only takes 5 minutes to install . I'm running 19/20 lbs of boost and 24* of timing w/Alky. and 104 octane boost in the tank. No more problems with boost control.
ATR sells them for $39.95 + $5 shipping (864) 972-3800
Part # CV100A AC CONTROL VALVE KIT GN

 

[rastaz]

Thanks guys,

Snappy, I assume that ATR kit comes with instructions cause I'm not sure I'm smart enough to install it properly without them. The wastegate solenoid is retained in this set up, right?

 

[UNGN]

Originally posted by rastaz
Thanks guys,

Snappy, I assume that ATR kit comes with instructions cause I'm not sure I'm smart enough to install it properly without them. The wastegate solenoid is retained in this set up, right?

The solenoid isn't used, but the actuator still is. You keep the solenoid pugged in, however, or you will get a malfunction code.

 

[Snappy6]

Thanks to all who Helped ...