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  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific Tech

Misfire Under Load

  • Thread starter Thread starter birel21y
  • Start date Start date Aug 14, 2008
B

birel21y

New Member
Jul 28, 2008
16
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0
Reno, Nv
Aug 14, 2008
#1
  • Aug 14, 2008
  • #1
I have been having this problem for a couple weeks now. Ever since i changed my plus, wires, cap and rotor, o2 sensors, and cleaned my MAF. It seems like an ignition problem, like its on and off running on 7 cylinders only under load, and missing. and it will do it more often when the engine is cold, or when i first start it up, and like i said, its only under load. Could this be a cracked spark plug? I was runing NGK Iridiums, but now im running the regular v-power plugs. Do i need Iridiums with my Crane Cams Fireball Ignition? There seems to be a high amount of resistance through the cap and rotor. they only have around 100 miles on them, and the brass tabs inside the cap are turning silver and black, and the conections look burnt ontthe rotor.

Heres the mods.cobra cam, ported / polished non smog Gt40 heads Trick flow valve springs hardened push rods, trick flow valve covers, 1" phenomic spacer matched upper / lower cobra intake, 75mm bbk throttle body, bbk intake, optima red top battery, ported mass air, underdrive pulleys, no air pump / egr, findanza 13lb. billet aluminum flywheel, centerforce dual friction clutch, 2004 mach 1 rear end with 355:1 gears, 180* thermostat. EXHAUST- bbk eaqual length shorty headers, bbk x-pipe, borla xr-1 cat-back. BRAKES / SUSPENSION- 10th anvrsy. red powdercoated cobra brakes, 13" vented / slotted / cross-drilled brembo rotors, steel braded brake lines, Tokico shocks all way around, eibach progressive rate springs, bbk upper / lower control arms, polyurathane rack bushings, a-arm bushings, transmission mount, subframe connectors. INTERIOR- 2004 Mach 1 seats / gauge bezel / Airbags / panels / center consol / shifter handle/ carpet / dash/ shifter bezel...ect, Autometer water temp and lean/rich gauges on A-piller mach 460 sound system, Windshield tint strip, 20% tint side windows, 5% on back 3 windows, short throw shifter. EXTERIOR- 17" mach 1 rims, 2004 mach 1 flat black wing, black trimmed taillights, cobra package, grillecraft silver grille.
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
33
129
Aug 14, 2008
#2
  • Aug 14, 2008
  • #2
Though you said it happens only under load, I'd try to run a cylinder balance test to see if it can pick up a slightly deficient cylinder.
 

BlackVert

15 Year Member
Oct 3, 2003
5,589
9
98
Bethesda, MD
Aug 14, 2008
#3
  • Aug 14, 2008
  • #3
yeah, that does sound like an ignition issue. probably a cracked plug or possibly a bad or loose wire
 

Bosko5.0

Active Member
May 18, 2006
1,067
0
37
longwood, FL
Aug 14, 2008
#4
  • Aug 14, 2008
  • #4
make sure your wire aren't cross firing.
 
T

tstang21

Member
Apr 14, 2008
219
0
16
Aug 15, 2008
#5
  • Aug 15, 2008
  • #5
agree. makes sure their not cross firing. check your plugs and wires to see any signs of wear. check your rotar as well
 
B

birel21y

New Member
Jul 28, 2008
16
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0
Reno, Nv
Aug 15, 2008
#6
  • Aug 15, 2008
  • #6
what do you mean cross firing? Like i mixed up my spark plug wires?
 
T

tstang21

Member
Apr 14, 2008
219
0
16
Aug 15, 2008
#7
  • Aug 15, 2008
  • #7
not that. i meant check your firing order to see if everything is in the right order. oh also check your tps voltage as well.
 
B

birel21y

New Member
Jul 28, 2008
16
0
0
Reno, Nv
Aug 15, 2008
#8
  • Aug 15, 2008
  • #8
what should i be running for rotor to cap clearance? its about 3mm right now.
 
B

biglar

New Member
Aug 21, 2007
33
0
0
pine beach nj
Aug 15, 2008
#9
  • Aug 15, 2008
  • #9
i had a similar problem and it turned out the dizzy went bad which is common on high mileage 5.0`s. when you take the cap and rotor off is there alot of black dust inside the dizzy? if so then the bearings on the dizzy are bad. replace with a new motorsposts dizzy

Hope this helps

Biglar
 
B

birel21y

New Member
Jul 28, 2008
16
0
0
Reno, Nv
Aug 19, 2008
#10
  • Aug 19, 2008
  • #10
Problem solved guys.... thanks for the help. It was just a cracked spark plug.
 
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