Boost fluctuation

[imjoesnuffy]

Have began working on the tune in my car. Have an odd fluctuation in boost.

When I get into the gas, pulls strong to 11-12 psi boost. Does a little flutter, backs down to 10 psi then goes on up to 17 psi no problem.???? Engine doesn't bog at all. DS header has been welded up. No vacuum leaks. I thought it might have been the gauge, but you can feel the car sort of plateau then keeps pulling whenever it happens??

I have a stock actuator, I need a HD one. But it is what I have at the moment.

KR 0.0
o2 780

Could it be the trans plus kicking in at WOT??? I adjusted the base timing +6 advanced and the WOT timing as well +2. I have 116 octane in the tank at the moment.

Any ideas would be appreciated,

 

[RUQWKNF]

Did this just start happening? Or has it been doing this for awhile?
Just for giggles, take the downpipe off the turbo and inspect the turbine wheel.
This is not normal and unless you have a leaking wastegate actuator, or a sticking puck, I suspect the turbo might be going south.
Just a thought.

Patrick

 

[imjoesnuffy]

Thanks Patrick,

Just bolted the turbo on at rebuild, 550 miles or so ago. Everything was fine then, zero shaft play, bought it from Grumpy with about 200 miles on it. Less than 1000 total miles and going south?? I have just started really getting into the boost. Didn't get over 5 psi during break in, took it real easy on it. I will pull the DP and check out the puck. I am running the vacuum line straight from the turbo to the actuator. Eventually going to get an RJC manual controller on there.

 

[RUQWKNF]

Then that being the case with the turbo, it should be good. I would suspect either the wastegate, wastegate puck or possibly a leaking hose or collapsing air inlet hose. Very odd, but I would check everything twice. Electrical and or fuel problem shouldn't do this to the boost. Especially with it hooked up "Tuner style."
HTH

Patrick

 

[86BLACKT]

Is turbo ported to puck size?? Just speaking from experience!!

 

[imjoesnuffy]

No the turbo is as it came from the factory. I am a little hesitant to carve on it.

 

[Chuck Leeper]

"I am running the vacuum line straight from the turbo to the actuator. Eventually going to get an RJC manual controller on there."
A stock actuator, and plumbed direct, and 17#?? As Patrick said, look at the w/g. The stock actuator should not be that high, when plumbed direct.
Also, an HD actuator will not allow you to go below about 17#, even with the controller backed off.

 

[86BLACKT]

Problem I had with 52 is the hole that the puck pushes against was too small, Mike Licht told me I had to port it to be a little smaller than puck, took care of the problem for me. I called him all pi$$ed off thinking I got ripped off, and he being the stand up guy he is gave me advice and it was 100% correct, the fluxuation went away

 

[gnx139]

can the WG hole be ported with the turbo on the car?

 

[RUQWKNF]

can the WG hole be ported with the turbo on the car?

Absolutely not recommended. It's best to take the housing completely off the turbo so that you can make 100% sure you get all the metal shavings out of the housing. Without doing this, any carbon or oily residue inside the housing will trap metal particles, then the first time you get on it and the turbine wheel starts to sing along at 110K RPM, those tiny specs of metal will take their toll on the turbine wheel. Not pretty. Some people have done it using a shop vac and rags in a pinch, heck I saw someone doing it at the track once, but I don't condone that type of practice.

HTH

Patrick

 

[86BLACKT]

Patrick is completely correct. I did mine on the car...but is definitely not recommended. The biggest PIA is the downpipe, and oil return line. I was luck, and had no damage...I am about 8 years older and wiser, and wouldn't do it again. Jack Cotton actually ported the 66BB that was dropped off on my porch today for my THDP. Thanks Jack!!

Regards
Rich