Re: Two problems

[rdh@genrad.com (Robert D. Houk)]

   OK, gang.  Two knotty ones:

Only two? You lucky devil . . .

   b) At full boost in third gear, the engine sometimes cuts out.  It picks up 
   again when the throttle is closed.

   Ideas and suggestions for either?

Other than the proverbial "Drink Heavily" . . .

What rpm range? (I finally determined my tach reads about 500rpm low at
6000, so I kept bumping into the rev limiter [with Dan's Schrick cam; 
this was never an issue with the factory cam!] "just before" I was ready
for it). This is primarily a 3rd-gear problem, as 2nd (and 1st!) spin
up so quickly that I am usually shifting by then anyways (so even if I
did hit the rev limiter, I am already degassing/declutching/etc.); and
4th (and 5th!) just don't really get that high in "normal" driving.

The '88 is (I would assume) quite a bit different from my '83, but I've
also found that the computer/boost is "right on the ragged edge" of the
computer shutting down due to overboost. In fact, the one drawback to
my S4 turbo upgrade that I just recently discovered is that if you hold
the engine to about 2000rpm (as in top gear uphill curve; or use the
brakes...) after 3-5 seconds the S4 turbo will build up enough boost --
the 7-8psi range -- to trip the overboost shutoff [least ways I'm pretty
sure this is what is happening]. When we first put in the new turbo (with
factory stock wastegate), the computer would sometimes "trip" on overboost
and cut the engine (around 10-11psi). The mechanic "diddled" the computer
(I think 'twas was a resistor either in series or parallel with the pres-
sure transducer) a bit to not trip until "14 or so" psi of boost.

If it's overboost shutoff, just "backing off slightly" on the throttle
should keep running; if you hold the throttle down and it cuts out momen-
tarily, cuts in and runs for a second or two, repeats then it sure sounds
like the overboost circuit cutting in.

Another thing that fooled me for awhile was "running low on gas"! I kid
you not. With what I thought was still "lots of gas" (4-5 gallons) still
in the tank, taking "my favorite onramp (nice curve)" would starve out
the fuel pump about two-thirds of the way through the curve, and only
really pushing it (and it seemed more inclined to bum out on left-handed
turns than on right, but I didn't really experiment all that much with it).
Coincidently enough, these are 3rd-gear onramps . . . once I learned to
keep lots and lots of gas in the tank for high-g turns, no more problem.
(of course it was real hard to reproduce, since I was through the curve
and straightening out, and just holding it to the floor evinced no fur-
ther "straight-line" problems, and I usually bought gas before I got back
to the onramp anyways...took awhile to make the correlation...)

Ah, cars with Personality, doncha just luv 'em!

Good luck.

					-RDH