87 5.0 backfires 1st - 2nd shift high rpm

Jay5_o

New Member

Jan 3, 2004

82

0

0

calgary, canada

Jul 4, 2004

#1

• Jul 4, 2004

• #1

Got a problem with backfire under load when shifting from 1st to 2nd 4500+ rpm. sounds like a gunshot going off, and its embarrasing when im raceing.
I got newer rotor ,cap ,spark plugs, wires
what would cause this? leaky injector ? wrong kind of spark splugs ?timing ?
any input would be helpfull to fix this problem

 

8

89rdgt

New Member

Apr 24, 2004

103

0

0

Washington

Jul 4, 2004

#2

• Jul 4, 2004

• #2

Well the off road h pipe doesnt do you any justice in that feild. It give a spot for extra fuel to burn after it leaves the engine. With no cats you tend to get a little backfire out the tail pipe. a bad injector could do it too.

 

281pony

Active Member

Aug 31, 2003

2,681

2

46

Oly, WA

Jul 4, 2004

#3

• Jul 4, 2004

• #3

i had the same problem. had an exhaust leak from mufflers to h-pipe

 

5.0Droptop

...all those nights we shared, and you're a dude??

Special Agent Mukity-Muck Whats in Charge Round Here

May 15, 2002

1,785

1,130

233

Indiana

Jul 4, 2004

#4

• Jul 4, 2004

• #4

Chek to be sure you vac line is still connected to the map sensor If you still SD. Make sure your Spout is plugged in also. Just a couple small things to chek.

 

Jay5_o

New Member

Jan 3, 2004

82

0

0

calgary, canada

Jul 4, 2004

#5

• Jul 4, 2004

• #5

"Chek to be sure you vac line is still connected to the map sensor If you still SD"

huh ? explain

 

T

TheUser

Active Member

Jul 25, 2003

1,859

1

36

Springfield, MO

Jul 4, 2004

#6

• Jul 4, 2004

• #6

If you have a timing light, check the timing. I believe that MAP sensor is on the firewall to the right of the upper intake and it has a vacuum line connected to it...check to make sure that it's in tact and not leaking.

 

5.0Droptop

...all those nights we shared, and you're a dude??

Special Agent Mukity-Muck Whats in Charge Round Here

May 15, 2002

1,785

1,130

233

Indiana

Jul 4, 2004

#7

• Jul 4, 2004

• #7

Jay5_o said:

"Chek to be sure you vac line is still connected to the map sensor If you still SD"

huh ? explain

Click to expand...

On Speed Density mustangs the MAP sensor reads the vacume from the manifold. If the line is off, kinked,leaking, etc it will cause problems. The map sensor is a black box next to the vacume tree its not in the center of fire wall but close to it.