help - 80Q engine suddenly lags on accel./check engine light intermittent

[Tessie McMillan]

Hi guys! Bear with me, this is long to get to the point. I recently put on
a fabulous exhaust system (www.stans-headers.com) with high-flow cat,
glasspack center exhaust, and Magna Flow rear exhaust. This is NOT a
problem but I think the new breathing is pointing out a
problem/maintenance issue I need to fix in my '88 80Q engine.

With the new exhaust on (which is fabulous, anyone in Seattle needs to go
visit Stan, he has a huge shop and you can just wander around
watching things happen), my car is totally zippy from the get-go. And if
you've driven a stock 80Q, you'll know that's saying a lot &:-). The
exhaust appeared to temporarily correct kind of a sluggishness I
had noticed before I had the exhaust put on, where anytime I
started from a full stop, put my foot down on the loud pedal, the engine
would lag (for a couple of one-onethousands) and then GO! I had tried
injector cleaner additives to my gas, running high octane gas, and
nothing helped *very much*. It seemed like the injector cleaner additive
helped a little, but then the problem came back again. So I'd try it
again, and it would help a little, and then the problem would come back.

Now as soon as the new exhaust was put on -- which I did because my old
system had rotted out completely and I had blown holes in the muffler
portions at a track event (the noise became unbearable) -- this problem
went immediately away for about three weeks. until a day after I drove
the car at the track again.

What is happening now -- from a day after the track -- is that on
sultry days or rainy days primarily, my check engine light will suddenly
come on about 5 minutes into driving. Then the car becomes sluggish at
acceleration and feels like it just isn't breathing properly. As soon as I
get it up to speed in any given gear, it runs fine, but giving it throttle
-- say to pass someone -- is a death-sign. The engine will just turn
sluggish again. What is puzzling is that this doesn't always happen! On a
cool, dry day, I don't have a problem. And I don't tend to have a problem
until the engine warms up. Also, when the light comes on, I sense that the
idle is rougher, and it fluctuates a bit, sometimes up to 1100 rpm,
sometimes down to 800.

The only clues I can add is that Stan told me that the exhaust note would
be fairly non-throaty until some carbon got deposited inside the two
mufflers -- then the note would change and become more throaty. Well, the
note has changed distinctly, so I assume some carbon has been laid down.

Any suggestions where I should start? Could this mean I'm running too
rich and/or fouled my plugs? (I would have thought track driving, high
rpms would help this -- in Alfa parlance we call this an Italian Tune-Up
&:-).) Pardon my ignorance if I say I'm not savvy to the kind of
maintenance I should be doing on my engine, so any PM suggestions and
advice are helpful. I'd like to get this sorted out before the next track
event...

Thanks!

Tess
in Seattle, WA, U.S.A.
'88 80Q (daily driver/track slut, yes, believe it!)
'72 911T -> becoming '73 RS replicar (slowly)
'87 Alfa Spider (learn to use the "cowl shimmy"!)