[Shotimes] Smog Woes

Fri, 5 Mar 2004 10:34:44 -0500

AC affecting idle.  That sounds familiar.  When my defroster is on,
the idle will sometimes drop enough to stall the car if I don't catch
it in time.  When I pull the intake off to finish the plug wire job I
plan to clean the IAB.  If that doesn't work, I'll have to start
trouble-shooting.

Mike Wojton
Toledo, Ohio

-'95 White MTX
   '96 Brake Upgrade

"Avoid the clap." - Jimmy Dugan

shotimes-admin@autox.team.net wrote on 03/05/2004 10:20:54 AM:

> I've been too busy at work to make much progress on the car, but I did 
get a
> new intake manifold gasket installed this week. I had mangled the 
previous
> one after removing the manifold after my first smog test - now at least 
I
> know it's not contributing to my woes.
> 
> Original test results with 80mm maf and lpm were as follows:
> 
>             Item    max/ave/meas
>  15mph       HC     114/31/38
>              CO     0.73/0.10/.01
>              NO     785/237/1064
> 
>  25mph       HC     88/20/34
>              CO     .61/.09/.01
>              NO     724/199/723
> 
> So I have some HC I could "trade" for NO with some lpm programming, I
> suppose. Not a very precise way of doing that, though, unless it can be 
done
> in real time.
> 
> My subsequent test attempt was done on a rainy day with the OEM maf 
setup
> (no lpm) and the spout plug pulled. That resulted in an aborted test, 
after
> several attempts, due to difficulties maintaining a constant rpm. I 
think
> Leigh's comment below regarding the AC system may be correct though - it 
was
> raining and the defroster may have been on. The AC system on this car 
does
> have issues that affect the rpm's when it kicks in.
> 
> The EGR passages are very clean. The back sides of the valves have a 
little
> crud on them, but from my untrained eye it doesn't seem like a lot.
> 
> The intake tract is pretty oily, but I believe this is a typical result 
of
> the PCV system, right?
> 
> Where do I get GM top cleaner and is this used in the gas tank or 
applied
> directly thru the intake?
> 
> Thanks much,
> 
>     Alan
> 
> 
> > Turn the A/C off, restart the car, and see if that helps. My 
compressor on
> > my 89 was seizing intermentantly, and it thru off the idle control 
computer
> > bigtime for over a year til I found it.
> > To check for vacuum leaks: disconnect hose at engine, need hand held 
vacuum
> > pump/guage, should hold.
> > I've seen leaks in hoses, connections, fittings, vacuum tank in 
fender, and
> > the vacuum pull hose for the cruise control down by the clutch pedal 
where
> > it rubbed thru the hose by the steering gear (my 94 with dead cruise).
> > Manifold vacuum leaks can be checked with a spray of some type at the 
gaket
> > area with engine running.
> > With all the mods you have you may need to check that your O2 sensors 
are
> > good, and the mixture is right. Did you get CO readings during you 
smog
> > check?
> > Good luck
> > Lee
> > 
> > 
> > ----- Original Message -----
> > From: "Alan Fanning" <Awfanning@earthlink.net>
> > To: "SHOtimes" <shotimes@autox.team.net>
> > Sent: Thursday, February 26, 2004 12:53 AM
> > Subject: [Shotimes] Smog Woes
> > 
> > 
> >> Between the weather (rain), work (12 hr days), and the SHO I'm about 
to go
> >> 'round the bend. I figured I was a shoe-in to pass smog today with 
cool
> > damp
> >> weather and the SPOUT plug pulled. No such luck - besides running 
like a
> >> pig, as you had warned, the engine wouldn't hold a steady rpm setting
> > while
> >> on the dyno and the test was ultimately aborted after several 
attempts.
> > Last
> >> time around (a couple weekends back) it seemed to hold rpm but 
wouldn't
> > pass
> >> on NOx.
> >> 
> >> I removed the intake last weekend to clean the EGR passages (didn't 
seem
> > to
> >> be clogged) and buggered up the gaskets in reinstalling the manifold. 
No
> >> spares, so I just put it back together. No doubt this didn't help 
matters,
> >> but one of the things that has puzzled me on this car from the get-go 
is
> >> that, with the trans in neutral or clutch pedal in, I can't get it to 
hold
> > a
> >> constant elevated rpm below about 2000 rpm. It either scoots up or 
down
> > from
> >> the point I'm trying to hold. Seems like a connected symptom. Vac 
leak
> >> maybe?  I've previously checked/replaced all the hoses and the intake
> >> gaskets.
> >> 
> >> I've got about 5k on new plugs, plug wires, O2 sensors, IAC valve, 
and
> > just
> >> about everything else that is replaceable. I was running a 55mm MAF 
which
> > I
> >> believe to be good, and no LPM. Spec's include Stage 1 cams, SHOShop 
3.2l
> >> w/10.5:1 compression, stock manifold, new/rebuilt OEM-spec injectors.
> > Engine
> >> seems a little rough at idle, but I have no way of telling whether 
it's
> > the
> >> cams or something else.
> >> 
> >> Any help appreciated. I'm about to run out of time (and patience) 
here.
> > It's
> >> a pretty car but...
> >> 
> >>     Alan
> >>     '91 SHO
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