really bad miss fire

[Mbxmitch]

Okay guys I'll make it short ans simple to see if you can help as I can't afford a shop right now.

Two days ago my truck started missing so bad that it would barely idle . Blowing black smoke from exhaust .

I did the usual check of sensors such as unplugging them cleaning them . Sprayed the coil and wires plugs to check for arcing . Plug and wires are brand new .

Cleaned the maf
Installed new coil pack
I know my cat is hollowed so no clogs
New filter new o2 sensors

Now if I unplug maf the truck will stay running just run rich and if I plug in maf it idles up and down until it dies.

Could it be a bad maf sensor ?

I was thinking stuck injector but why would it run better with the maf unplugged?

 

[RonD]

On the injector rail is the Fuel Pump Regulator(FPR)
It is controlled by a vacuum line, remove this line and check it for gas or gas smell.
If the diaphragm cracks inside the FPR unmetered fuel is sucked in cause flooding based on vacuum so worse at idle.

Unplugging the MAF sensor puts computer(PCM) in Open Loop so most other sensors are off line and fuel/air mix it from a preset table based on TPS(throttle position)

One of my new spark plugs died after a few months, just driving along and it started missing, plug look good but was dead as a doornail

Also if you have an EGR system the the valve can get stuck open from carbon build up, or the valve is being opened by a bad sensor.

 

[Mbxmitch]

No egr

The plug problem you mention . A month ago someone pointed out that I had a missing cylender so I went and changed the plugs and it fixed it. Plugs looked good though