fluctuating boost @ full throttle with t3/t4

[tiresmoke69]

Here is the problem description: when I do a 3rd or 4th gear pull, boost comes up to 15 psi and then fluctuates between 12 and 15 psi under full throttle.

Here is a video of a 4th gear pull with this occuring ( watch the boost gauge ): s264.photobucket.com/albums/ii161/thinkskater14/?action=view¤t=001-1.flv It is hard to tell in the video, but when it fluctuates the car rocks back and forth from it.

Checks I have done so far:

Boost leak tested (found 3 leaks and fixed them), but no change with fluctuation prob.

I am using a ball/ spring boost controller.

I have my wastegate actuator vaccum lines ran as follows: from the top port of the actuator to the vaccum tree ( with boost controller in between ). I have tried hooking the bottom port to a vaccum source, and all it does is make the boost stay at 10 psi no matter what the B/C is set at.

I have check my adjustable WG actuator arm and it is tight and has preload.

I am kind of stumped on this one... any helpful ideas would be great....

Here are 2 pics of the type of actuator that is on my t3/t4

[svojohn]

Connect the top port directly to the compressor housing. Connect the bottom port to your boost controller and connect the boost controller to the intake manifold.

[tiresmoke69]

Ok I did exactly what you said, but then it wouldnt go over like 6 psi ( no matter what the boost controller was set at ). I connected the top port to the boost controller, then to the manifold. Bottom port to compressor housing. After doing this the fluctuation prob is still there, no change.

On the way back from my run the car decided to go dead for no reason. I check the fuel lines and i have good fuel pressure. I checked the coil and spark plugs and they are firing. Non of the sensors are unplugged. I noticed that when I turn the key on the rpm gauge was sweeping, so I figured a ground came loose. I couldnt find any grounds loose. Also when I turn the key on there is a buzzing noise coming from a black box right next to the VAM. I have never heard this noise before so im guessing that is the prob.

Here are some pictures of the black box making the buzzing sound.

[Stinger]

That's the IRCM (Integrated Relay Control Module). A relay buzzing means there is a wiring issue elsewhere typically.

[tiresmoke69]

I will see if i can fix that tomorrow so I can get back to the fluctuating boost problem... Im thinking its going to be my wastegate because i dont know of any other reason for the fluctuation to occur.

[chris98gt]

Hey, did you ever figure out what the problem was? we just put new t3/t4 setup on out 88tc swapped mustang and seem to be having the same issue. Was it a problem with the wastegate or something else?

[tiresmoke69]

Yes, it was the wastegate actuator. I borrowed one off of a subaru just to test it out and it worked great. I think my diaphram was torn inside the actuator causing it to fluctuate. I would try a different actuator.