7-6-7 Boost Pattern, Blocked CAT?
 

7-6-7 Boost Pattern.

After a few weeks of changing vacuum hoses, renewing gaskets and tightening/replacing hoses etc I now have a 7-6-7 Boost Pattern (better than my previous 7-5-2!). The car performs exceptionally well now J.

At 6500 – 7000 rpm it dies (i.e. acceleration / boost stops).
From what I understand boost is supposed to hold while redline?
Is this a classic case of a blocked main cat?
Would a blocked main cat explain the lower boost reading?
Could the new boost gauge be faulty as I understand I need 8psi to operate the 2nd turbo, but it is definitely coming in and holding 7psi…

The car has twin K&N Cone filters and a replaced downpipe (’92 Jap import ‘R’ Type)

Any help appreciated…

These are the symptoms of a clogged main cat or precat. Eventually as the clog gets worse, the boost pattern drops to 4-0-4...

I would agree. I had 8-6-8 & suffered from a clogged precat. I'm sure a clogged cat would be the same.

Did you remove your pills when changing out your vacuum lines? This will give you 7lbs of boost.

Re: 7-6-7 Boost Pattern, Blocked CAT?
 

Assuming no pills were removed from your turbo precontrol hose, or your precontrol/wastegate actuator solenoids are working properly, I would check the main cat or precat. The converters are good for no more 70,000 miles or so.

This thread was my experience with a clogged cat. I figured it out toward end of the thread. Ignore the unproductive posts from one of my "haters"...

https://www.rx7club.com/showthread.p...&highlight=404

When you figure out your problem PLEASE follow up on your thread, so you can contribute to the community's knowledge on FD3S sequential turbo problems.

Re: 7-6-7 Boost Pattern, Blocked CAT?
 

Urban myth. You can have 0psi on the primary and still get full secondary. It could be the cat, but seeing as 7psi is the wastegate spring pressure I'd be very suspicious about that.

As others have said, check the wastegate inline restrictor. It sounds like everything is working except boost control.

-pete

Did you remove your pills when changing out your vacuum lines? This will give you 7lbs of boost.

The hoses have been changed at some time (in Japan). I pulled one off last night (turbo precontrol) to see if i could see a pill, there apeared to be nothing in the hose at all :eek:

What does a pill look like?

Why would this only give me 7psi instead of 10psi?

Does this explain the car dying at 7k?

Thanks for all the help :cool:

When you figure out your problem PLEASE follow up on your thread, so you can contribute to the community's knowledge on FD3S sequential turbo problems.[/

One of my pet hates on previous forums....:mad:

They look like "Pills" with a small hole in the center. The pill should be in the boost and prespool hoses. Make sure you are pulling the correct hoses. If the pills are removed, you will get exactly 7lbs of boost on both turbos. You can also tell if you blow through the hose. There is a lot of restricition with the pills in.

Let me know what you find.

Checked the pills last night, what pills? The hoses were completely empty!!! That would explain the 7psi. Manufactured some pills myself (with a 2mm hole drilled through (0.079" for you foreigners!)) to see if it made a difference, got more boost :D

Now it's time to source the correct size pills from somewhere here in the UK...:(

Looks like i have got to the end of my low boost problem...

Thanks to everyone who gave help ;)

Good to here you figured it out. Instead of buying the pills you should make a home depot style boost controller. Try searching the forum, there are a lot of threads on this.

Might just do that, not having much luck here.......

You might check Summit Racing (not sure if they'll ship to you or not):

http://www.summitracing.com/

There's some more info in this thread:

https://www.rx7club.com/showthread.p...hreadid=226647