Boost Fade/Falling/Dropping Problem

[4gfun]

I have posted bits and pieces about this in other threads but it is now my primary problem. Please no comments about multiple threads on the same topic since this is a new primary issue.

I have set my MBC at 22 psi with my Big 16g. By 4500 rpm, boost drops to 20 psi. By redline, it is at 17 psi.

I have replaced the MBC just in case it is an issue and still have the same problem.

I have Boost Leak Tested the system with a 6 gallon compressor and have been able to take the pressure up to 30 psi. I do hear air from the valve cover oil cap when I remove it even when timing is set to 30 degrees ATDC. It is not as bad as others have described and I don't want to go broke spending too much money and time on valve stem seals if it not the cause of the boost fade. In fact, I have read that hearing some air from the valve cover opening during a BLT is normal. All BLT are performed cold.

Compression is 161-165 across the board.

I have replaced the throttle shaft seals and put RTV over the BISS Screw opening due to boost leaks. I put the one way check valve to the PCV as well.

My BLT situation is far better than it was before overall and I am not so sure I want to continue to blame boost leaks for this issue.

I have also gotten a Dodge Modded BOV (I really think it looks more like the Dejon but others say it is Dodge Modded).

All of this and I still have the above Boost Fade Problem. In fact, someone else had or has an identical issue:

Is Boost fade normal? - DSM Forums: Mitsubishi Eclipse, Plymouth Laser, and Eagle Talon Forum: DSMtalk.com

All of my mods are in the signature. (Note the 40mm Tial Wastegate). The spring is 16 psi. The wastegate is apparently 10 years old. I contacted Tial to find out more about it since the previous owner installed it. Maybe the spring is tired after that long? (They didn't seem too worried about it).

Could you all give me your thoughts?

Thanks!

 

[LiquidX]

I have set my MBC at 22 psi with my Big 16g. By 4500 rpm, boost drops to 20 psi. By redline, it is at 17 psi.

Depending on mods it's normal for boost for fall by redline. My 16g didn't hold solid the whole way either.

I have Boost Leak Tested the system with a 6 gallon compressor and have been able to take the pressure up to 30 psi. I do hear air from the valve cover oil cap when I remove it even when timing is set to 30 degrees ATDC. It is not as bad as others have described and I don't want to go broke spending too much money and time on valve stem seals if it not the cause of the boost fade. In fact, I have read that hearing some air from the valve cover opening during a BLT is normal. All BLT are performed cold.

Block/pinch off the hose going to the PCV and if your leak from the oil cap goes away then your PCV is leaking (get new OEM unit or a check valve from US Plastic)

I have replaced the throttle shaft seals and put RTV over the BISS Screw opening due to boost leaks. I put the one way check valve to the PCV as well.

Put the check valve on the right way?

 

[4gfun]

Thanks...what about for my mods? I don't think it is normal...but who am I?

What was the behavior of your 16g was it a big or small 16g?
I have read that either should.

The check valve is in the right way. No air is coming in from the check valve.

I just pulled the cat down and still have the same behavior.

Any other thoughts from you or any one?

Depending on mods it's normal for boost for fall by redline. My 16g didn't hold solid the whole way either.


Block/pinch off the hose going to the PCV and if your leak from the oil cap goes away then your PCV is leaking (get new OEM unit or a check valve from US Plastic)


Put the check valve on the right way?

Anyone? You all dropped quite a bit of relevant information in my other posts but I am still stuck on this.

Please help!