car misses randomly

[98gtmustang64]

At low rpm it will miss but if i go wot it will stop and it happens randomly to ive replaced plugs, wires, and coil packs thinking it was electrical but it still does it and its starting to make me angry

 

[wmburns]

Mods? Under drive pulleys?

Underdrive pulleys are bad about messing up the crank shaft position sensor signal. Some are worse than others. If the damper is bad, lose, incorrectly torqued this can cause problems like you are having.

 

[GDawg]

Our cars aren't meant to be driven at low rpms. If you stomp on it at 2000 rpm not much is going to happen if not hickup.

 

[98gtmustang64]

when im in town that kind of low rpm and when im cruisin down the highway at like 70 it will do it for awhile and then it will just stop

 

[98gtmustang64]

and yea i do have underdrive pulleys

 

[GDawg]

When's the last time you changed your fuel filter? Have you ever ran fuel injector cleaner on your injectors?

 

[trinity_gt]

When did the missing start? Did you do any mods (specifically, the UDPs) to the car and notice it was suddenly missing?

 

[98gtmustang64]

it started along time ago but then it didnt do it for awhile and now its doin it again i had my mods on before this started happening and i just replaced the fuel filter and i have ran cleaner through it

 

[califsp]

If you don't have any codes it sounds like a bad oxygen sensor

 

[pilks]

If you don't have any codes it sounds like a bad oxygen sensor

i'd second the oxygen sensor

check the voltage on those bad boys

 

[wmburns]

IMO, An O2 sensor isn't likely to cause a MISFIRE.

If you are positive this isn't an ignition problem (or crank shaft sensor), look first at the MAF for a sudden loss in power. Clean it using a product designed for the purpose.

This could also be an EGR problem (excessive flow, EGR valve leaking), or an evaporative purge problem (VMV valve stuck open).

To confirm the diagnosis, monitor the LTFT (both banks), RPM, load, TPS, and air flow with an ODB2 scanner.