Miata Mailing List: January 1996, Message #16
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   From: Eric_Rowland@BayNetworks.COM (Eric Rowland)
Subject: Bad gas
   Date: Tue, 2 Jan 1996 00:49:53 -0500

TOC:
1) Bad gas - what to do?
2) Spark plugs for a supercharged car
3) Motorsport adjustable sway bars
4) Santa's gifts to Lightning

1) No, no!!  Not from the holidays!
It appears that Lightning picked up a bad tank of petrol (for you non-US
types) the other day.  A few miles after filling up, I was cruising along
highway and felt a misfire and saw the tach blip.  Sure enough, as I drove
further it happened again, and then more often.  
When it misses, it feels like it's running out of gas (I unfortunately know
how that feels), more like a whole cycle is missed, vs. a single cylinder. 
It happens occasionally, but isn't repeatable.  Sometimes happens on
acceleration, other times it's just fine.  Most times it's just while I'm
cruising along and it's a single missed pulse, but sometimes it's several and
sounds (and feels) terrible!
I've now run a tank and a half of new gas, a bottle of gas dryer and a bottle
of Techroline through it over a few hundred miles.  I've also replaced the
spark plug wires (I'm at 28K miles) and pulled the plugs, which looked clean,
with a light coating of soot.
My next step is to check my MSD connections (I've disabled the SC already, to
try to isolate it and the AFPR)  I still think it was the gas, but am
surprised that I haven't burned through the shitty stuff yet.  
Thought I'd check the wisdom on the 'net for further suggestions.  Is it
possible (relatively easy) to drain the gas tank, in case there's some really
big crap in there that's fouling the fuel pickup?
I'll probably replace the plugs (they only have 10K miles on them) just
'cause they're cheap and easy (I like 'em like that).  I can't think of
anything else that would be bad (it's either fuel or spark), 'cept maybe the
ECU, and it doesn't act like that.  Could the unique dual coil ignition make
one bad plug act like two bad plugs?
I'm a DIY guy and hope I don't have to resort to a service provider, but if
this ends up costing me $$ and it was the gas, I'm gonna raise some hell at
the gas station!!
Thanks for any help!

2)  Spark Plugs - The Mazda book gives three different heat options for spark
plugs.  I understand that I shouldn't use Splitfires, since they may run too
hot on a 'charged car.  I'm currently running the NGK xxx6xx  plug, installed
by the dealer.  Should I run the coldest plug, assuming that the 'charger
will keep things sufficiently hot?  (Convention says 'hot rodders' use hotter
plugs to get more power)

3)  Installed the MotorSport adjustable sway bars (front & rear) a few months
ago.  Like the firmness, but the car seemed to feel a bit looser in the
corners, tending toward oversteer (eek!).  Since I can ALWAYS induce
oversteer with throttle I adjusted the front bar for more understeer and it
feels a lot better now.  Anyone else have these - where do you have them set?

4)  Lightning's stocking was EMPTY this Christmas!  :-(  Guess I'll have to
take advantage of the after Christmas sales so she doesn't feel bad...
But we DID go on a several hundred mile trip yesterday, gifts in the trunk,
top down and Santa hat on (me).  Several honks and waves - the truckers
seemed to get a kick out of it.  Don't know how cold it was, but hat, scarf,
heavy leather jacket, gloves and heater on full made it comfortable.  Hat's
on (too cold to have them off) to you guys in the cold climates.

Eric & Lightning  (fuming and sputtering, respectively, 'cause of bad gas)
'91B w/supercharger, Borla, an empty stocking and a bad attitude (to be cured
with lighted mirror)
Santa Clara, CA