Need some help with a P0305 code
#1
Need some help with a P0305 code
Ill try to keep the background story short and to the point. I used to be a ford tech, so this kind of work is second nature for me.
I bought a 97 F150 with a 4.2 with 180,000 miles with a blown head gasket on cylinder 3. Had misfire codes for cylinder 2, 3, and 5. Replaced both head gaskets, intake gaskets, injector o rings, pintle caps, plugs, wires, coil. Runs good now expect for a skip at idle, bad enough to eventually set a P0305 code.
Swapped 4 and 5 injector, plug and wire. Code remains cylinder 5. Replaced coil with no change. Aside from the skip at idle the truck runs great. Towed a car 100 miles with it today. No issue off the line or cruising. Only at idle.
Checked all injectors with a stethoscope and they are all firing. Unplugged and capped EGR line just to see, no change. Compression is app 120 on all 6. Plug from cylinder 5 (has 200 miles on it just like the rest) looks the same as every other plug in the engine.
If you pull #5 plug wire while running there is a noticeable change in the idle, its gets worse. Acts like the cylinder is low on compression almost but its not.
I am lost and out of ideas.
I bought a 97 F150 with a 4.2 with 180,000 miles with a blown head gasket on cylinder 3. Had misfire codes for cylinder 2, 3, and 5. Replaced both head gaskets, intake gaskets, injector o rings, pintle caps, plugs, wires, coil. Runs good now expect for a skip at idle, bad enough to eventually set a P0305 code.
Swapped 4 and 5 injector, plug and wire. Code remains cylinder 5. Replaced coil with no change. Aside from the skip at idle the truck runs great. Towed a car 100 miles with it today. No issue off the line or cruising. Only at idle.
Checked all injectors with a stethoscope and they are all firing. Unplugged and capped EGR line just to see, no change. Compression is app 120 on all 6. Plug from cylinder 5 (has 200 miles on it just like the rest) looks the same as every other plug in the engine.
If you pull #5 plug wire while running there is a noticeable change in the idle, its gets worse. Acts like the cylinder is low on compression almost but its not.
I am lost and out of ideas.
#3
#4
#6
I find brake fluid works better than carb cleaner . If there is a leak , it will find it . I would do a leakdown test and running compression test next . I was thinking GM firing order when I mentioned piston travel . Lots of heads have small " cracks " between the valve seats . As long as they do not extend too far , no worries . We use to peen them , back when , if we found them .
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