latest on boost saga

Wed Dec 17 21:42:19 PST 2008

Thanks Mike,

i'm sure you read that 034 feels pretty confident that the problem was corroded ground wires and terminals. they did remove the exhaust from the cats back, thinking it was an exhaust issue. didn't help, but the car sounded really cool ;-)

see ya,
Robby

--- On Wed, 12/17/08, Mike Miller <mikemilr at blackfoot.net> wrote:
From: Mike Miller <mikemilr at blackfoot.net>
Subject: Re: latest on boost saga
To: centaurus3200 at yahoo.com, 200q20v at audifans.com
Date: Wednesday, December 17, 2008, 7:21 PM

Hi Robby,

I'll take a stab at it here as I have BTDT with low 
boost when I bought my 1st 200q in 1996. I had a normal reading on the WGFV but 
it was bad - Ned Ritchie of IA and I spent many hours troubleshooting 
it and I think mine was the 3rd one found to be bad in the US. Took over a month 
to get the part from the father land.

If you pinch of that hose from the WGFV to the WG, 
you will remove ALL ECU control of the WG. Have you done that yet? 

You say you have a new Bypass valve correctly 
installed. Have you verified the hose the entire length from the back of the 
Intake Manifold to the Bypass valve? If anything is bad ( like it is crimped at 
the bracket on the back of the IM) the Bypass valve will dump boost 
prematurely.

Good to hear you have the Samco's - that should 
eliminate any leaks there - which would show up on a pressure test anyways. 

I don't recall what you are seeing for low boost 
when you do experience it. Is it possible the car is in limp home mode ( 1.3-1.4 
bar) due to a bad MAF sensor? Try to borrow one if possible as they are quite 
expensive.

There is a high altitude sensor - when I turn on my 
key at 5000 ft elev. the boost gauge reads .9 or .8 bar. With stock ECU I would 
never see over 1.7 bar and yet I would get 1.8 bar under about 3000 ft 
elev. At 10k+ ft elev boost was limited to 1.6 bar as I recall. The purpose here 
is to prevent over spinning the turbo in the thinner high alt. air. I guess they 
figured 100k rpm was enough :-)

Basically, the WGFV is the way the ECU controls 
boost - it pulses the WG and prevents it opening at lower boost and then it 
allows it to open as you approach the max boost your ECU allows. If you exceed 
max boost ( like with the hose pinched off or a stiffer WG spring) the ECU 
will ground the fuel pump and not allow you to exceed 1.3-1.4 bar until the 
ignition is cycled.  

Your problem (to me) sounds like an issue with 
either the hose to the bypass valve or a flaky MAF sensor. If you are running a 
K&N air filter, some people have experienced the oil from the filter coating 
and ruining the MAF sensor - I have never had the problem personally. I am 
assuming you have checked the air filter - I did have a rodent build a nest in 
my F350 airbox a few yrs ago the severly limited boost. Little SOB chewed out 
the bottom of the filter and used it and sone underhood insulation for nesting 
material. Went from 24 lbs boost to 14 lbs.

You may not know that you can driil out the top of 
the WG in the center and tighten down the screw inside to increase spring 
pressure - allows for faster spool up of the turbo - same as putting in a 
stiffer WG spring only "free".

I think I saw where you said you had checked 
*every* fuse in the fuse box. I think there are a couple there that will limit 
boost - like that double one nearest the fender in the middle with "moteur" or 
something like that labeled on it.

Just out of curiosity, what are you seeing for fuel 
economy? I'm running an MTM chip ( have run stock and Hoppen stage 1) and I see 
21-22 around town and 25-28 hwy. The reason I ask is that a clogged Cat-con can 
cause low mileage and low boost. A loose part in the exhaust will occasionally 
allow normal performance. Just one more thing to look at :-)

hope some of that is useful

mike

----- Original Message ----- 
From: robert 
weinberg 
To: 200q20v at audifans.com 
Sent: Wednesday, December 17, 2008 5:53 PM
Subject: Re: latest on boost saga

hi mike,

it's an 034 billet bypass. it was installed 
correctly.

i wish i knew what the stock ecu did but i bought the car with 
a dead autocheck. boost, trip, etc. i chipped the car while it was still 
dead.

i developed the boost issues. somewhere in between, i got around to 
frankensteining a another dash's electronics (that white flip down back panel) 
onto my dash which fixed the autcheck, et al.

i'm also running samco 
hoses - any leaky boost and vaccuum lines were just replaced by 
034.

there's definitely something screwy going on with the computer and 
the wgfv. it's reading 1.4 bar like it's not even connected - but it is. 034 
tried a known working valve. no change. they measured the correct signal from 
the computer to the connector.

but something is getting mixed up. and 
sometimes, it works and the car is a flippen rocket.

help me learn, what 
is the purpose of the whole WGFV system? to allow the computer to lower boost at 
high altitude?

from my understanding, that's the only time the computer 
lowers boost. it does not lower boost during detonation, correct? only pulls out 
timing.

Regards,
Robby

--- On Wed, 12/17/08, Mike Miller <mikemilr at blackfoot.net> 
wrote:
From: Mike Miller <mikemilr at blackfoot.net>
Subject: 
Re: latest on boost saga
To: 200q20v at audifans.com
Date: Wednesday, 
December 17, 2008, 4:39 PM

I forget - has the turbo bypass valve been 
replaced and is it hooked up
correctly? It is easy to hook up backwards which 
I believe can limit boost. What
kind of boost does a stock ECU make when 
installed?

mike

----- Original Message ----- 
From: Chris 
Miller 
To: 200q20v at audifans.com 

Sent: Wednesday, December 17, 2008 5:15 PM
Subject: Re: latest on boost 
saga

I'd hook up a test light (LED) to the wastegate frequency valve 
(WGFV).
That way you can watch what the computer is telling the WGFV to 
do.  If I
recall correctly, the LED should light up solid then flash 
rapidly as boost
builds.  If the light stops flashing or goes off, that 
means the signal from
the computer is not closing the WGFV and you'll have 
the 1.4 bar boost max.
Make the lead to the LED long enough and you can stick 
the LED under the
windshield wiper and watch it while driving (or run it in 
the window to the
dash).

Check the basics, too; grounds; wiring 
condition at the multifunction temp
sensor; condition of the gear on the end 
of the distributor.

Chris

On Wed, Dec 17, 2008 at 
10:42 AM, robert weinberg
<centaurus3200 at yahoo.com>
wrote:

034 
says they GAURANTEE they've checked every flippen sensor or possibility
with 
the car. at least she did boost for a little bit with my computer. Dan
at 034 
said he can believe the ecu going bad - like the pressure transducer
- but 
what would make for a flakey chip? they are open to 
suggestions.

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