Flutter under boost

[viperman5]

I am getting a flutter when I hit 10psi. Truck runs great, no codes, spools fine, can make boost as long as under 10 psi, it feels fine. Hit 10 psi, power goes away and I start hearing a flutter sound coming from the turbo area. You can feel it in the truck slightly.

Here is what I have done:
Took air filter off to make sure it was not coming from intake and re-secured.

Took turbo to IC hose off and re-secured.

Thought my IC to Throttle body was loose. took off and used T-bolts to secure.

Thought my boost control solenoid was bad so I went back to boost valve.

Thought wastegate actuator was bad, took off put old working one back on.

Prior to this happening, had wastegate ported, 3"DP put on. Truck ran fine when I got it back for about three weeks.

Any help would be appreciated.

Jay

 

[Tooky]

Re: Flutter under boost

Need more info..... post your mods, and/or a Datamaster file of this event occuring.

Has your truck had a recent ignition tuneup? Too large a spark plug gap from well-worn plugs would cause this.

 

[mpulsev10]

Re: Flutter under boost

How many miles ? Have you ever changed your timing chain and gear? I just had to do mine, you could hear a light rattle and the knock sensor would throw the timing out of wack. Now its great with a new chain/gear.

 

[viperman5]

Re: Flutter under boost

Mods, custom tune, 60# injectors, 20g turbo w/ 50 trim wheel, ALKY injected, 3"DP, removed catcon, ATR exhaust, plugs were just changed 800 miles and regapped to .028. The ALKY and 20+psi were giving me problems with the stock gap.

Truck has 26K.

While I had the wheel well out, I was checking out my 3"DP and checking for any leaks. All was good however.... the band clamp between the exhaust housing and compressor housing was loose enough, I could turn it by hand. I tightened it down but haven't been able to drive. It has rained all weekend in Chicago.

Could that be causing my problems?

PS - I work out of town so I can get Datamaster on it Friday.

 

[turrrbo6]

Re: Flutter under boost

Do you have an aftermarket ign. box ? You have got to keep the sparks lit with alky.

 

[Syclone#2960]

Re: Flutter under boost

I kind of having the same issue.

 

[Daryl H]

Re: Flutter under boost

What kind of hose are you using to the intake of the turbo?
It may be collapsing under the vacuum.

 

[turbodig]

Re: Flutter under boost

Mods, custom tune, 60# injectors, 20g turbo w/ 50 trim wheel, ALKY injected, 3"DP, removed catcon, ATR exhaust, plugs were just changed 800 miles and regapped to .028. The ALKY and 20+psi were giving me problems with the stock gap.

Truck has 26K.

While I had the wheel well out, I was checking out my 3"DP and checking for any leaks. All was good however.... the band clamp between the exhaust housing and compressor housing was loose enough, I could turn it by hand. I tightened it down but haven't been able to drive. It has rained all weekend in Chicago.

Could that be causing my problems?

PS - I work out of town so I can get Datamaster on it Friday.

Sounds like you burned a plug wire. My bet would be #6, but all of the ones on the turbo side can be suspect.

Also check your AFR at WOT... too much fuel can blow out even a good ignition.

 

[Tooky]

Re: Flutter under boost

While I had the wheel well out, I was checking out my 3"DP and checking for any leaks. All was good however.... the band clamp between the exhaust housing and compressor housing was loose enough, I could turn it by hand. I tightened it down but haven't been able to drive. It has rained all weekend in Chicago.

Could that be causing my problems?

PS - I work out of town so I can get Datamaster on it Friday.

Wow, if that clamp is loose I guess there's no telling what could happen. If your housings are not true they could leak boost or even worse, contact the wheels (it's a very close fit). Curious to see what the results of your test drive are. I know it won't be any time soon though because I live in the same area (Milwaukee) and this MONSOON feels like it will never end!! :roll: :lol:

 

[viperman5]

Re: Flutter under boost

I am running the Goodyear hose that is recommended on another site. This is the same hose I have been using for a couple years. I can understand the collapse under vacuum but my issue is under boost and specifically over 10 psi.

I am leaning/hoping that I have solved it with tightening the band clamp or maybe the plug wires with the big ole DP. I did check out the wires but only to see if they are touching the DP.

I will provide feedback when back home. The wife gets us moved, I find a local project and now we move back to Chicago. Travel now Monday thru Thursday.

Thanks for all the help everyone.

BTW - I was not very mechanically inclined prior to this truck. Also the 3.8 turbos are so much easier. I feel like a proctologist working on this truck compared to the Buicks.

What kind of hose are you using to the intake of the turbo?
It may be collapsing under the vacuum.

 

[viperman5]

Re: Flutter under boost

Also check your AFR at WOT... too much fuel can blow out even a good ignition.

Interesting... I do have wideband on the truck. It does run on the "safe" or rich side under full boost. At least I have another avenue if I haven't fixed it.

 

[Daryl H]

Re: Flutter under boost

Intake of the turbo not intake of the engine.
What hose do you have going to your turbo?

I am running the Goodyear hose that is recommended on another site. This is the same hose I have been using for a couple years. I can understand the collapse under vacuum but my issue is under boost and specifically over 10 psi.

I am leaning/hoping that I have solved it with tightening the band clamp or maybe the plug wires with the big ole DP. I did check out the wires but only to see if they are touching the DP.

I will provide feedback when back home. The wife gets us moved, I find a local project and now we move back to Chicago. Travel now Monday thru Thursday.

Thanks for all the help everyone.

BTW - I was not very mechanically inclined prior to this truck. Also the 3.8 turbos are so much easier. I feel like a proctologist working on this truck compared to the Buicks.

 

[Jimmy]

Re: Flutter under boost

IMHO the fluttering sound is the turbo to IC or IC to TB connection.

That is where the pressurized air goes.

So the engine feels good but you are hearing a boost loss,or is the engine bucking as well?

 

[viperman5]

Re: Flutter under boost

That is the reason I checked the turbo to IC then IC to TB first. I thought for sure that was the cause..

The truck runs great, I drove it from Indy to Chicago with no problems. It spools fast like it used to, if I am part throttle and keep it under 10 psi it pulls as normal. At or around 10 psi, I hear the flutter around the turbo area, I can feel a slight vibration consistent with the flutter, boost will keep going up but power falls off then boost falls off. No bucking, it just doesn't go like normal 20 psi blasts.

IMHO the fluttering sound is the turbo to IC or IC to TB connection.

That is where the pressurized air goes.

So the engine feels good but you are hearing a boost loss,or is the engine bucking as well?

 

[sy2639]

Re: Flutter under boost

Did you have the exact same symptom before reinstalling the boostvalve? The reason I ask is because my boostvalve makes a flutter like noise when it hits its pressure setting.

I am getting a flutter when I hit 10psi. Truck runs great, no codes, spools fine, can make boost as long as under 10 psi, it feels fine. Hit 10 psi, power goes away and I start hearing a flutter sound coming from the turbo area. You can feel it in the truck slightly.

Here is what I have done:
Took air filter off to make sure it was not coming from intake and re-secured.

Took turbo to IC hose off and re-secured.

Thought my IC to Throttle body was loose. took off and used T-bolts to secure.

Thought my boost control solenoid was bad so I went back to boost valve.

Thought wastegate actuator was bad, took off put old working one back on.

Prior to this happening, had wastegate ported, 3"DP put on. Truck ran fine when I got it back for about three weeks.

Any help would be appreciated.

Jay

 

[Vertigo]

Re: Flutter under boost

I'm with Jimmy
Definitely sounds like a boost leak. It won't run rich since it's a MAP-based system so the only negatives you'll find are possibly noise and a hotter intake charge (low power).

Do a bike tube pressure test.

 

[viperman5]

Re: Flutter under boost

Hey Josh, I went to the boost valve because I thought stock solenoid/actuator was causing the flutter so I get it with both.

With is a bike pressure test?

Thanks again for all the help.

Jay

Did you have the exact same symptom before reinstalling the boostvalve? The reason I ask is because my boostvalve makes a flutter like noise when it hits its pressure setting.

 

[Flyin Ryan]

Re: Flutter under boost

With is a bike pressure test?

http://www.sytyarchives.com/howto/viewarticle.php?article_name=find_vacuum_leak.php&dir=engine

 

[UR50SLO]

Re: Flutter under boost

I get the same thing when I get spark blow out on the wife's Typhoon... 10psi is the place it starts to happen. Part throttle/mid throttle ok up to 10lbs then at WOT it'd sputter and power fall off/boost fall off. This was all before the engine rebuild but the main problem was spark blowout.
I ended up putting a MSD 6AL,Blaster coil and a set of NGK Irridium plugs gapped at .30
Have not had a issue with old engine or new engine since.
I don't run Alky on anything.
If there's no boost leak then it's sparky going pooof !!!
~Scott

 

[viperman5]

Re: Flutter under boost

Sorry for the delayed response. I waited for a set of UR6 plugs. The tighten band clamp and new plugs still didn't cure my problems. Still the flutter above 10psi. Today I recorded two short DM files. These are both from 2nd gear, part throttle until it hits the flutter. If someone can help me look at them and provide feedback, I would appreciate it.

If it is spark blow by, would should I look at replacing?