911GT2

It's been asked, and yes I've searched. However I can't seem to find a real answer to the question. So here goes:

Boost pattern:
1st: 0-0-0
2nd: 0-0-0
3rd: 0-0-0
4th: 10-8-10
5th: 10-8-10

If I'm going uphill and I hold the throttle steady (not WOT, but maybe half) in 3rd gear, I get boost, then I can floor it and get full boost. Not quite 10-8-10, but maybe 9-7-9.

I've traced the check-valve lines and replaced 2 valves. The other one is fine.

I tried unplugging the wastegate and pre-control solenoids, and the boost pattern remained the same (except max boost was 7 psi). I was under the impression that unplugging these should relinquish turbo control to the wastegate spring, so I should get a solid 7 psi. Any help there?

I thought for a while it might be a clogged pre-cat (car is completely stock). But it seems to spool quickly in 4th and 5th, so I have trouble imagining that it would not spool AT ALL in lower gears if the pre-cat was clogged. I have never felt the stock sequential system operate properly, so I don't know how fast it should spool, but it seems quick.

I'm selling the car, but trying to fix it before I do. Anyone have an idea of where to check from here?

RotaryBred

damn bro... very strange problem if u ask me.. are u running a boost controller?

Heisenberg

iTrader: (3)

I had the same problem. But it would only do it in first gear. After I put the DP and PFC on the car it went away.

dgeesaman

iTrader: (7)

I would start with the KOKO test on fd3s.net.

http://www.fd3s.net/boost_test.html

And any of the primary turbo troubleshooting on the autosportracetech site.

That way you can start with the basics: vacuum, pressure, etc.

Dave

911GT2

No boost controller, car is completely stock.


First gear problems are more common from what I've read while trying to find my issue. I considered just putting on a downpipe and seeing if that cured it, but I get the feeling that's not the problem.

I read through both of those sites extensively trying to find something that sounds like it could be causing this, and so far have come up with nothing. It feels like a massive boost leak, but only in low gears. And it is incredibly consistent. I don't have tons of time to spend working on the car so I was looking for somewhere to concentrate my efforts.

What boggles my mind is that it works so well in 4th and 5th... and yet not at all in 1st 2nd and 3rd.

Here's a question for the stock sequential guys: Cruising along in 4th, say 3k rpm or so, if I go WOT, there is a 1.5-2 second delay before the turbos build any boost. Is this normal? (despite almost 3 years of owning an FD, I have NEVER felt the stock sequential system working properly!)

Mahjik

iTrader: (1)

Start with the KOKO test as dgeesaman mentioned up above. It sounds like your turbo control system is not working properly. When it has problems, it manifest itself in the lower gears (because you rake through those pretty fast). It's odd that you have the problem in 3rd.

Either way, you need to start eliminating things. Start with the KOKO test to check the turbo control system. You aren't going to find that needle in the haystack just by standing back and trying to eyeball it's location.

IRPerformance

iTrader: (41)

A lazy/sticky solenoid will sometimes cause the symptoms you are describing. Start testing them per the mazda manual.

dgeesaman

iTrader: (7)

I think that kind of comprehensive work is a little out of scope at this point. But if it were my car and I could spend the time, that's what I would prefer to do too.

Dave