Weird boost pattern: 14-5-5
 

Okay, like the title says, I'm apparently getting a WOT boost pattern in 3rd of 14-5-5. I have NO idea where to start with diagnosis. I lose power over 10psi, so I've naturally avoided it even before installing the boost gauge (which is sweet as hell; GReddy V2 FTW) but at WOT, that's what happens. 14psi, cut cut cut until transition, drops to 5psi and stays there the whole RPM range.

I have searched, but I'm feeling woefully overwhelmed at the possibilities. I'm thinking I might just take the car in and have the rat's nest redone, but that's a lot of money, especially if the problem is relatively easy to fix, and especially since I'm staring down an eventual rebuild.

I'd like to have this issue resolved BEFORE I have the engine rebuilt... I'd hate to accidentally spike 14psi on a fresh motor...

Thoughts? Thanks in advance.

What are the airflow mods on the car?

First, what are your mods. 14psi on the primary... with no real transition... sounds like your wastegate is not opening at all. And it also sounds like you are getting no secondary. Try this thread:

https://www.rx7club.com/showthread.p...ht=boost+issue

Lots of people smarter than me posted in this one, but I haven't read everything to see if there is any relevance.
https://www.rx7club.com/showthread.p...ht=boost+issue

also try here: http://www.autosportracetech.com/RX-...leshooting.htm

There are no airflow mods on the car. Based on what I'm reading, it looks like I lost the connection between the primary compressor and the pre-control wastegate. I'm finding that I'll need to have the primary working before I should even be looking at the secondary, so I'll start with the spiking and go from there.

I'll pull the UIM and snap some shots this weekend. I've already been told that the rat's nest is going to need some real work. No one has said how much, though. Heh.

So your saying your third gear pull got you 14psi on the primary and then fell off to 5 at transition, then stayed at 5 back to red line. First of all you only need to make 8 psi on the primary to be able to transition to the secondary. You didn't say what ECU you are running to be at 14 psi even on the primary turbo, so it sure looks like your losing your pressure when the secondary comes on which wold seem like a leak some where in the secondary part of the system, not in the rats net. Losing that much pressure 14 psi to 5psi I would think you would hear that leak.

14 psi on a stock car indicates a problem with the wastegate or the line from the primary turbo to the wastegate actuator (or pre-control actuator).

Much appreciated, but the car is stock. The 14psi spike comes with power loss, presumably from fuel cut, after 10psi. If I feather the throttle around 9psi under 3500 RPM, I get smooth power, but it doesn't matter if I mash the throttle or not after 4500... there's never any more than 5-6psi.

I'm sticking with the problem being in the rat's nest. The primary shouldn't be making 14psi at all. When I've figured THAT out, I'll start puzzling about the secondary. No use stressing top end boost if I have to tip toe around town as it is.

Since your car is stock, you need to get the primary boost down to 10 psi or it won't matter that you only make 5 psi on the secondary, your going to damage the motor putting 14 psi on a stock setup. Once you have the primary to 10 psi then you need to find the boost leak in the secondary part of the system, since it drops off after the CRV is supposed to close (either it's leaking) or one of the hoses has a split in it. Get your primary in check first and then go for the leak.

Update: I finally broke down and took the car to MazdaTrix. I'll post up as I learn of their diagnoses of the problem. (I figure I owe it to would-be searchers to "complete" this thread for them.)