Car: Mr2 turbo 1991
 
Problem: Ive got a problem with boost drop that i still havent figured out. Boost will get up to 17psi and will drop down to 12-14 psi at around 5000rpm onwards...
 
With my old set up i ran the following mods:
-2.5inch exhaust with knocked out cat
-Aftermarket side mount cooler
-Standard ECU with FCD
-Ct26
-Turbotech manual boost T set to 17psi (these are pretty reliable, used them on many of my other cars i used to own.)
 
I than upgraded ecu to Blitz Acess ecu, i also upgraded turbo to CT20b and that didnt fix the boost drop.
 
I need ideas on what i could try to resolve this boost drop pls:
So far its not:
turbo
actuator
ecu
 
Other possibilities? aftermarket IC? Standard knocked out cat? Ideas please.
 
Thanks for reading, ADZ.

Have you disconnected the T-VSV valve from the wastegate?
On the wastegate there is two hose connections.
One goes to the turbo compressor or intercooler pipe.The other goes to a valve under the inlet manifold which the ecu uses to limit boost when the engine is cold or when knocking etc.
If you haven't already done so, block off that second connection on the wastegate so you only have the one conection to the turbo compressor or IC pipe.
 
Does that sense?
 
If you have already done the above then i have no idea what the problem is :)
 

Ye ive already done that thx. Any other ideas?

I wonder if you just getting a spike to 17psi, but stables at 12psi?

Or possibly ign break down in higher rpm?

Wouldnt think boost leak.

What BOV are you using?

just_ace

I wonder if you just getting a spike to 17psi, but stables at 12psi?

Or possibly ign break down in higher rpm?

Wouldnt think boost leak.

I may or may not be.
In my opinion its not because ive started with 10 psi and gradually upped my boost. Holds 17 psi from 2 800rpm to about 4500rpm and than the dropping starts...

MR2QIK

What BOV are you using?

Standard BOV...
Is the knocked out standard cat maybe causing the boost drop?

Even though you may think the Turbotech MBC can ruled out, I would still try another MBC and also check the length of vac hose to the actuator etc. shorter the better.

Also the standard downpipe and Cat is pretty restrictive regardless of thw guts having been knocked out of it.

MRTurbo

Even though you may think the Turbotech MBC can ruled out, I would still try another MBC and also check the length of vac hose to the actuator etc. shorter the better.

Also the standard downpipe and Cat is pretty restrictive regardless of thw guts having been knocked out of it.

Yea, the vac lines are pretty short. Guess ill borrow mates BC and make sure that its not my boost T.
After that i guess all that is left is downpipe, and if that doesnt fix it, ill look at the cooler, as i dont know what brand my aftermarket cooler is...

The std dump wroth cat punched out should still allow decent boost to redline shouldnt drop that much.

Either way should still get a 3 in dump.