[s-cars] Saga continues: Miss not from bad WGFV - Could it be the MAF?

[Walsh, Edward]

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Hi Bob,

I recently swapped in spark plugs and the entire coil pack (including
plug connectors) from fellow lister Ian Duff's 95.5 S6A.  Although he
runs stock boost, his components are known good.

My car ran the same as it did with my own components.......

Thank you for the input, Ed

-----Original Message-----
From: Robert Myers [mailto:robert at s-cars.org]
Sent: Thursday, April 10, 2003 4:15 PM
To: Walsh, Edward
Subject: Re: [s-cars] Saga continues: Miss not from bad WGFV - Could it
be the MAF?



Ed,

This _still_ sounds like some sort of an ignition problem to me.  You
state "plugs are good".  How do you know this?  They are new?  You also
state "plug connectors all have 5K ohm resistance".  That's good.  What
is the condition of the insulation for these connectors?  I have seen
stumbling behavior very similar to what you describe caused by leaking
plug wires.  These were wires on am '89 200 rather than the boots of our
S-cars but the comparison is still valid.  These wires had perfectly
good internal resistances but were leaking voltage  (and therefore
current) through the insulation.  This caused a weak spark which was
insufficiently strong to ignite a high pressure fuel/air mixture when
boost levels were high.  Do you have a known good set of plug boots
available for substitution into your engine?


At 02:03 PM 4/10/2003 -0400, you wrote:



I realize this thread is getting old, but WTF,  I need da boost.  The
WGFV
is OK, so here is where we, err , I stand:

95 S6 with 83k

- Plug connectors all have 5K ohm resistance
- Plugs are good
- ECU is good
- WGFV is good
- Coil pack is good
- Idle is smooth
- New O2 Sensor
- Turbo is quiet
- Waste Gate is not torn, slides smoothly up and down with no play
- Power is smooth until about 1 bar
- Miss is subtle, but prevents boost from hitting 22-23 (MTM 1+) in all
but
gears, boost fluctuates from 17-20.5 in 5th gear
- Miss is worst when accelerating hard on the Hway, after coasting in
heavy
vacuum for a while (like slowing for traffic on a 2 lane road,
downshifting
from 5th to 4th, then overtaking on the left - big stumbles/brown pants)
- Miss is most apparent when engine is COOL
- Motor will over boost to 28+ PSI if floored at low RPM (<2,500) in
3/4/5
gear.  When boost is that high, the motor makes a different, very rapid
"thumping" noise.  ECU will sometimes bring boost down to safe levels,
but
sometimes it won't, and only my right foot prevents a grenade.

Everything in the ignition system checks out.  Boost plumbing seems
fine.
Could the MAF be throwing bad values to the ECU under high boost? (I use
paper filters)  Is there a test procedure for the MAF?  Could a bad MAF
cause the mentioned symptoms?

Thanks for any/all advice,

Ed


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____

I've been wondering...  Who would Jesus bomb?

Bob
*****
 Robert L. Myers  304-574-2372
 Rt. 4, Box 57,  Fayetteville, WV 25840 USA  WV tag Q SHIP
 '95 urS6 Cashmere Grey - der Wunderwagen   ICQ 22170244
  http://www.cob-net.org/church/pvcob.htm
<http://www.cob-net.org/church/pvcob.htm>
*****