5 and 8 misfire
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rairh (03-25-2018)
03-24-2018, 02:53 PM
#3
Burning Brakes
does the problem clear up under acceleration? If so you could be running too lean of a mixture at idle, check for a vacuum leak around the intake manifold.
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rairh (03-25-2018)
03-24-2018, 04:50 PM
#4
how did you determine you have a misfire?
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rairh (03-25-2018)
03-24-2018, 07:47 PM
#5
03-24-2018, 07:49 PM
#6
put new cap,new rotor, new plugs,new wires. It idles a little rough. Can’t tell it going down the road but when I pull the wires off of 5 and 8 it doesn’t change anything.
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rairh (03-25-2018)
03-24-2018, 08:00 PM
#8
Safety Car
Did it run fine before you replaced the cap, rotor, and wires? If so, check your plug wires for proper firing order again. When all of a sudden two cylinders on different banks are not working and you just made changes, look at the changes.
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rairh (03-25-2018)
03-24-2018, 08:49 PM
#9
no it was doing it before. Is it possible the guy that put the intake on didn’t get it on correct or the gaskets correct because 5 and 8 are right across from each other?
03-24-2018, 08:50 PM
#10
03-24-2018, 08:54 PM
#11
03-24-2018, 09:05 PM
#12
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St. Jude Donor '22
if, if the pickup coil is firing the cyls,
pull valve covers
pull spark plugs
pull dist cap
put engine top dead center #1 fire
note rotor position in dist
hand turn crank watching valves and measure
with dial indicator or small ruler (a good cyl) to
get how much it moves.
measure the valve movement on the bad cyl.
i tend not to go into too much detail because you need to understand on your own
pull valve covers
pull spark plugs
pull dist cap
put engine top dead center #1 fire
note rotor position in dist
hand turn crank watching valves and measure
with dial indicator or small ruler (a good cyl) to
get how much it moves.
measure the valve movement on the bad cyl.
i tend not to go into too much detail because you need to understand on your own
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rairh (03-25-2018)
03-24-2018, 11:36 PM
#13
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On dual planes those two cylinders are usually connected. A vacuum leak can do it. Often there's a big vacuum port on that runner series...plug it off and ck. Could be leaking vacuum booster, headlight tank, etc. Is PCV hooked up there?
JIM
JIM
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rairh (03-25-2018)
he checked idle mix screws. he said smelled rich
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rairh (03-25-2018)
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rairh (03-25-2018)
03-25-2018, 09:15 AM
#16
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make sure your wires are run correctly first. easiest first then get into it up to your elbows.
Then check for spark, then start looking for a vacuum leak. Opposite sides of the cap is a big clue
Then check for spark, then start looking for a vacuum leak. Opposite sides of the cap is a big clue
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rairh (03-25-2018)
03-25-2018, 10:47 AM
#17
did you check if the intake bolts are loose?
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rairh (03-26-2018)
03-27-2018, 07:08 AM
#19
still on 5 and 8 misfire
i took intake off to inspect the intake was replaced right before i got it should back water jackets be pluged off on intake manifold this is a 350 1980
03-27-2018, 08:08 AM
#20
Heel & Toe
Just picked up on this thread.
I'm not sure what you meant by "companion cylinders".
The firing order is 1843 6572 so 5 & 7 are sequential the firing order.
It has been known for cross fire to happen as the leads run close to each other.
You stated "misfire" just confirming you don't mean "crossfire"
Are your plug leads correct on the Distributor?
Mitch
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rairh (03-28-2018)