misfire problem getting me pist off

aleborjas

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Sep 11, 2005

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Sep 10, 2006

#1

• Sep 10, 2006

• #1

hi, i have a 98' cobra with vortech 10 psi , 42 pounders (no FMU is unplugued sinse i put 42 pounds) and when the engine is arround 5K and up (WOT) the car starts poping by the exhaust looks like misfire, the spark plugs looks ok im using Motorcraft 22C Cooper no platinum, calibrated at 0.35 i whant to try autolite 103, the other thing i think it could be are the spark plugs wires and the coil packs they are the stock ones...
Any sugestions with spark plugs, wires, coils what to buy or what to do?

P.S. i have 75 HP shot but when i push it it pops even more and i dont have any fuel press problems in iddle 38 pounds and full 50 pounds so the problem is not there...

realy need help with this i have a war with some chevys...

 

fastangboi

My first set of nuts vibrated themselves off.

Jul 26, 2006

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Slowville

Sep 10, 2006

#2

• Sep 10, 2006

• #2

try getting an air/fuel reading. lean its fuel system, rich its ignition.

thats the best i got

 

stangGT97

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Dec 22, 2004

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Sep 10, 2006

#3

• Sep 10, 2006

• #3

well if you suspect it is ignition related - when was your last plug wire change? also, running 10lbs on factory coil packs might be part of the problem.. if it isn't giving an intense enough spark, you could be spitting unburnt fuel out the tail pipes, and causing that popping sound you hear.

Pick up a haynes manual and check the primary and secondary resistances according to the procedure laid out in the book. If out of spec, you may want to invest in a set of Screamin' demon coil packs + livewires... that will be more than enough spark for you. You're sure it isn't detonation? Just want to make sure that's been ruled out

 

aleborjas

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Sep 11, 2005

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Sep 11, 2006

#4

• Sep 11, 2006

• #4

the tail pipes are black when i lowered the fuel press the car felt better when i had the FMU conected i had black smoke when i hit the pedal to the floor and without the FMU i have 50 pounds at WOT because i have 2 fuel pumps. thats why i think is electrical problem or spark!
the spark plugs wires are very very old they have like 5 years and the coils are the stock ones... and the car really pops and it does it worst when is hot

 

stangGT97

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Dec 22, 2004

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Sep 11, 2006

#5

• Sep 11, 2006

• #5

5 year old spark plug wires?? I would start with replacing those first... but I seriously think if you're gonna replace the wires, do the whole thing and get the screamin' demon coil packs + live wires.

 

M

my95gtstang

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May 9, 2004

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Chesapeake, VA

Sep 11, 2006

#6

• Sep 11, 2006

• #6

i have the same problem. but mines not up at 5k its all the time and it smokes like a hot girl in a cold place. when im just sitting at a stoplight it looks like im burning out and all im doing is idling. im waitin for her to blow up. what all problems i could have. it pops, smokes, runs rich and is misfiring. how could i fix this?
changed sparkplugs to platinum plugs, it seems like its burning oil and fuel and maybe water getting into my cylinder heads.

 

stangGT97

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Sep 11, 2006

#7

• Sep 11, 2006

• #7

my95gtstang said:

i have the same problem. but mines not up at 5k its all the time and it smokes like a hot girl in a cold place. when im just sitting at a stoplight it looks like im burning out and all im doing is idling. im waitin for her to blow up. what all problems i could have. it pops, smokes, runs rich and is misfiring. how could i fix this?
changed sparkplugs to platinum plugs, it seems like its burning oil and fuel and maybe water getting into my cylinder heads.

Click to expand...

better do a compression test... and could be a blown headgasket if you're blowing white smoke from the tail pipes.

 

aleborjas

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Sep 11, 2005

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Sep 11, 2006

#8

• Sep 11, 2006

• #8

stangGT97 said:

5 year old spark plug wires?? I would start with replacing those first... but I seriously think if you're gonna replace the wires, do the whole thing and get the screamin' demon coil packs + live wires.

Click to expand...

thanks for the info wich are the best coil packs? i dont realy like much MSD coils i see more spark with the stock ones i try that on a 5.0 i dont know on this car any other good brand some realy good spark coils? and for the canles i think im going to order the ford racing ones...

 

stangGT97

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Dec 22, 2004

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Sep 11, 2006

#9

• Sep 11, 2006

• #9

Aleborjas, for your application, I would highly recommend the screamin' demon coils + livewires (sold as a kit). If you really don't want to go that route for whatever reason, then Accel coils are pretty good as well.

 

M

my95gtstang

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Sep 11, 2006

#10

• Sep 11, 2006

• #10

or MSD

 

stangGT97

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Sep 11, 2006

#11

• Sep 11, 2006

• #11

my95gtstang said:

or MSD

Click to expand...

well he said he didn't want msd, but yes that is also a viable option, although I haven't used them before..

 

M

my95gtstang

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May 9, 2004

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Sep 12, 2006

#12

• Sep 12, 2006

• #12

oh i didnt see that part. yeah im going to be gettin MSD.

 

aleborjas

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Sep 13, 2006

#13

• Sep 13, 2006

• #13

hi where can i find screamin' demon coils + livewires? in florida? to get them as soon as posible...
other thing is wich plugs can o use sometimes i use 75 shot, i run motorcraft 22C right now i whanted to try autolite 103 any other brand or something like that?
and thanks all for the help!

 

stangGT97

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Dec 22, 2004

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Sep 13, 2006

#14

• Sep 13, 2006

• #14

aleborjas said:

hi where can i find screamin' demon coils + livewires? in florida? to get them as soon as posible...
other thing is wich plugs can o use sometimes i use 75 shot, i run motorcraft 22C right now i whanted to try autolite 103 any other brand or something like that?
and thanks all for the help!

Click to expand...

the 22Cs should be fine, not sure if you should go down another heat range for the blower + nitrous. As far as getting the coils, it looks like they are an online only thing
http://www.performancedistributors.com/4.6ignition.htm

 

aleborjas

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Sep 19, 2006

#15

• Sep 19, 2006

• #15

hi, i can't decide between screamin coil or Boost a spark from kenny bell wich one is better? i whant the best because i have boost + shot and i'm going for 150HP shot, and the BAS work with the stock coils?

 

T

Two Wheel Peel

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Sep 19, 2006

#16

• Sep 19, 2006

• #16

Years ago, my friend had the same exact problem you are describing. It turned out that something was wrong with his bypass valve not working. He was blowing 14lbs. through a Powerdyne blower on a 90GT. Everytime he would get on it, it would let out some loud backfires that sounded like gun shots going off. He got a Vortec bypass valve put on and the problem went away.

 

stangGT97

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Dec 22, 2004

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Sep 20, 2006

#17

• Sep 20, 2006

• #17

Two Wheel Peel said:

Years ago, my friend had the same exact problem you are describing. It turned out that something was wrong with his bypass valve not working. He was blowing 14lbs. through a Powerdyne blower on a 90GT. Everytime he would get on it, it would let out some loud backfires that sounded like gun shots going off. He got a Vortec bypass valve put on and the problem went away.

Click to expand...

that could be it, but his spark plug wires are over 5 years old and with all the extra fuel and air, hes probably not getting a very good spark to get complete combustion.

check all of these things then report back

 

aleborjas

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Oct 16, 2006

#18

• Oct 16, 2006

• #18

hi, i was on a trip and only yeterday i ordered the spark plugs cables, what i did today was to close the plug gap to 0.25" and the problem is 98% gone now it makes it arround 6800RPM's(i feel the car rough in iddle when i closed the plugs why?), i'm going to try new cables and gap the plugs back to 0.35" and see what happens. I checked the coils and they are both good...