Hey guys, I have been chasing a misfire on this truck for a while now. So far I have changed, coil packs, o2 sensors (had codes), cleaned EGR ports in the throttle body (had low flow codes) and fuel filter. I just checked dpfe sensor voltage tonight. Key on, engine off, top (signal) wire when back-probed was at around 1.1 Volts. Is this in spec? Also, I bought a code reader with mode 6 and checked out the test $53 data in hopes of discovering what cylinders were missing. Well, it’s saying that cylinders 1-8 are OK, but cylinders 9 and 10 are missing. What does this mean considering the engine is a v8?

One more thing to note, not sure if related. The interior dome lights are “pulsating” so to speak at idle and truck seems to turn over a little slower than normal. Battery is brand new. Could this be correlated to the engine missing, and if not, what would cause it? Thank you all for your time.
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Check your plugs and wires.
Revisit the code reader and make sure your getting useful information
Check your alternator for pulsing interior lights

 

cleaned EGR ports in the throttle body (had low flow codes)

Just about bet that you will get the EGR code again as the EGR pressure sensor that sets just in front of the EGR that has the two rubber lines coming to it with a plugin is going bad. DO NOT GET A CHEAP ONE FROM CHINA. Spend the $130.00 and go to Ford and get theirs. They are heavier than the cheap ones and have a better wiring field in them. (On a note this is a Ford problem from day one on these trucks and Ford changed this sensor and they say change them out at 100,000 miles.

The interior dome lights are “pulsating” so to speak at idle and the truck seems to turn over a little slower than normal.

Is the door open? Could be the door switch going out or whatever. Could be ground at the driver's side kick panel.
How old is the starter?
Have you checked your wires running to the starter to make sure they are still good?

Have you changed the plug wires?

 

Just about bet that you will get the EGR code again as the EGR pressure sensor that sets just in front of the EGR that has the two rubber lines coming to it with a plugin is going bad. DO NOT GET A CHEAP ONE FROM CHINA. Spend the $130.00 and go to Ford and get theirs. They are heavier than the cheap ones and have a better wiring field in them. (On a note this is a Ford problem from day one on these trucks and Ford changed this sensor and they say change them out at 100,000 miles.

Is the door open? Could be the door switch going out or whatever. Could be ground at the driver's side kick panel.
How old is the starter?
Have you checked your wires running to the starter to make sure they are still good?

Have you changed the plug wires?[/QUOTE]


Will change out that pressure sensor.

I will try to locate the ground you speak of for the pulsating dome lights.

I checked starter connections, all looks okay and the cables seem to be in good shape.

As for the plug wires, I have changed them. But it’s been a year or two, and they were a set I found on Amazon. They all look okay, but i know that doesn’t mean much on plug wires.

 

we had a 2007 4.6 motor that had a missfire.. chased for a couple years. New plugs and coils would help, then back to missfire a few weeks later..... Finally changed the injectors and problem gone for 4 years.

 

Does it misfire only when it's raining?