99F350V10 |
04-23-2012 06:04 PM |
1999 F350 6.8L V10 No Code miss
My 1999 F350 6.8L V10 has a slight (and what seems to be intermittant) miss. My code reader (Innova 3100) returns no errors, however. Any ideas on what I can test next? Here is what I've tried so far . . . .
(1) Installed new spark plugs. - Although the plugs that were removed were that old, I replaced all of the plugs with new ones after properly gapping each per Chilton's manual.
(2) Performed fuel pressure test. Fuel pressure with key on and engine off equals 34 psi, which is within the recommended range specefied by Chilton's manual.
The leak-back <2 psi in 5 minutes (well within spec).
With engine running, fuel pressure dropped to 28 psi (normal).
Acquired resistance readings on fuel injectors (all within 11-18 ohm range as specified in Chilton's manual).
(4) With engine running @ ~1500rpm, coils packs unplugged one at a time. - Each time one of the coil packs was unplugged, there was a noticeable change in engine performance. This led me to conclude that each coil pack and plug was indeed working fine.
I did receive a comment from another shade tree mechanic about a a possible fault in the computer board. But I do not know how to test this, or even where it is located on the vehicle. Any advice here?
|