overboosting --> my 86 5ktq

[Larry C Leung]

The coil signal gets cut off by the ECU in an overboost condtion. See the
ABC's of (High) Boost in Scott Mockry's site sjmautotechnik.com  (or
something thereabouts, see the audifans.com website, vendor listing to be
certain of the website address) to understand ALL of the details on boost
on the I-5 cars. After you read this rather comprehensive site, you'll be
better equipped to ask questions.

LL - NY

On Fri, 30 Nov 2001 13:27:10 -0800 Brian Devlin <bdevlin at stanford.edu>
writes:
>My main goal is to get more boost quicker, rather than higher
>pressures. As it is right now, the turbo barely has a chance to work
>in first gear before I shift, and there's noticable lag at every
>shift.
>
>Part 1: the frequency valve
>What interests me more about this is that the claim that boost comes
>on sooner. If I understand correctly from things I've read here, the
>wastegate setup in these cars bleeds off some pressure all the time.
>So it seems that modulating this tube/valve would be a way to get
>boost quicker. I'm just not sure how the frequency valve is actually
>working.
>Part 2: the spring
>My car did come with a boost spring, in the glove box. If I install
>it, I was thinking of using a 4kq relay (probably any NA relay) for
>the fuel pump. This type of relay uses a signal from the coil to turn
>on and off, so it wouldn't be as dangerous as jumpering the relay.
>Anybody out there try this?
>Part 3: the "chip"
>Anybody have btdt on the chip mods vs jumpers? Like hp vs engine
>damage?
>-Brian
>
>this all started with:
>
>>On the way home from the QCUSA driver's school at Sears Point (my
>car
>>was just parked there, I was taking pictures) my car developed a
>massive
>>overboost problem. Perfectly drivable as long as I keep my foot out
>of
>>it, but boost comes on much stronger and at lower RPMs than
>usual...at
>>minimal throttle I hit 1.8 bar on the gauge and hit overboost (qlcc
>>chip, Scott Mockry 1.8 bar spring...like a Charlie spring). I made
>it
>>home fine, in fact didn't hit overboost once after realizing what was
>up
>>and keeping my foot out of it.
>>
>>I stopped to take a peak at a gas station, but not much light. No
>>obvious hose problems at the WG lower chamber so I am guessing it is
>a
>>sticking WG (doubtful, this came on all of a sudden), or more likely,
>a
>>torn WG diaphragm.