Coil on cyl. #1 and #5 been replaced. but check engine light still on. DTC still exist. all sparkplug been replaced,fuel injectors been cleaned.
SOURCE: 1988 ford f150 302ci miss
possible bent push rod or colapised lifter
open the valve cover and start the truck make sure all the rocker arms are moving
SOURCE: engine code p0307 cylinder #7 misfire
It could be carbon deposits on valve seats keeping valves from totally closing. You can try getting you a can of motorcraft PM3 top end engine cleaner and get engine up to operating temp then remove one of the small vacuum lines from the intake and draw the contents of the can slowly into the engine.After you have drawn in the contents shut engine off and let it soak for about 45 minutes then crank it back up and let it run until it clears. Now it will smoke like a forrest fire while you are doing this so don't be alarmed,just tell the neighbors you are spraying for mosqitos.This may cure the problem. If not you may be looking at a valve job.
This can be verified with a compression test if this is what is causing it.
SOURCE: I have a 2005 ford ranger 3.0L with repetitive engine codes
these engines did have some exh valve issues, service bulletin 05-26-3. one other thing to verify is that the cam synronizer (CMP) is correctly installed. if its not right on, its way off.
SOURCE: Engine misfires on #1 cyl. Code P0301. plug, fuel
Then the coil is bad. Even if the specs were ok, which they r not, the cracked case means its junk.
SOURCE: vehicle came in for check
A misfire at idle that smooths out at cruise is ALMOST ALWAYS caused by a vacuum leak. Take a hard look at your fuel trims at idle. If the Bank 2 Long Term Fuel Trim is more than + a couple points higher than the Bank 1 trim, your problem is most likely a vacuum leak. If the Fuel Trims even-out while holding the engine at 2000 RPM for about 20 seconds, then a vacuum leak is DEFINITELY your problem. I would suspect a leaking lower intake gasket leak because an upper plenum leak will normally affect all cylinders.
2004 Marauder and 2003-2004 Mustang vehicles built before 12/19/2004 equipped with 4.6L 4V/5.4 4V engine may exhibit a runs rough, lacks power, and engine misfire, prompted by a MIL light and DTC codes P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, and P0316.
ACTION
Diagnose engine for engine misfire concern. If diagnostics determine an engine misfire which is characterized by leakage through exhaust valve(s), only replace the affected cylinder head(s).
SERVICE PROCEDURE FOR VEHICLES WITH RUNS ROUGH/MISFIRE CONDITION:
1. Perform relative compression check on all cylinders. If abnormal, check cylinder leakage and actual compression for "low" cylinders refer to Workshop Manual (WSM), Section 303-00.
2. If leakage/compression check indicates a valve train concern, per valve train diagnostics in WSM, Section 303-00, replace cylinder head and cam assembly, pipe plugs and timing chain tensioner, per procedure outlined in WSM, Section 303-01.
3. If cylinder leakage and compression tests are inconclusive, perform misfire diagnostic, per TSB 05-22-8.
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