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P0307 (M) Cylinder #7 Mis-Fire Misfire detected in cylinder #7.

40K views 17 replies 5 participants last post by  zzzzzzz 
#1 ·
what will get this to come on ?
i was thinking my cam sensor ?
spark plug,tested by moving to other side
spark plug gap,tested
spark plug wires, tested by moving to other side
coil,tested by moving to other side
fuel injector,tested by moving to other side
wiring connectors to injector,tested
wiring connectors to the coil, tested
do compression test,tested and ok
check oxygen sensors not tested but why would just one cyl be bad ?

if tested by moving to other side did not move to the new cyl#
i'm at a lost for what to try

on the cam wheel or part that the sensor sees is #7 the one with lest teeth ?
 
#2 ·
What's the year and engine?
 
#3 ·
If you have a 5.2/5.9 you certainly didn't move the coil from one bank to the other because there is only one. If you have a 4.7L you couldn't have moved S.plus wires from side to side because they are coil on plug Ign. So as Rick99 asked what engine? 4.7L you might have a failing coil or injector drivers in the module. 5.2/5.9L possibly the magnetic pickup in the base of the distributor is bad. This controls the fuel injector timing so it’s important
 
#4 ·
hemimech said:
If you have a 5.2/5.9 you certainly didn't move the coil from one bank to the other because there is only one. If you have a 4.7L you couldn't have moved S.plus wires from side to side because they are coil on plug Ign.
That's what I was getting at, the stuff you said you did just doesn't add up. If you want us to help (and we'll be glad to), you've got to tell us what you've actually done so far and what engine this is. The reason most people will focus on the simple stuff first is because, if it is all good, you are lead to replace seriously more expensive parts.
 
#5 ·
surrey
it is a 2000 4.7 with 175k km on her and an eng that has 200k km on it

with the "spark plug wires, tested by moving to other side" i was off on this the shop i was at told me how they had tested things was by moving thing to the other side and i thought it had wires .i'm trying to keep the cost down and i think he was pulling out his hair on this one
 
#6 ·
do a laek down test..........bad valve may not show up in a simple compression test............another would be an intake leak in #7 intake runner causing lean missfires...............is it really that cylinder???? 3rd one back drivers side??
 
#8 ·
just need to check inj driver with a simple noid light.......check coil driver the same way.............just to make sure the pcm is grounding them as it's suppossed to............i'd be doing a leak down test.............i might also remove the valve cover to check the valve springs....................
 
#10 ·
As stated above, use a noid light to try to find out if the fuel or the Ignition is dead on cyl #7. If you find one that the light doesn’t flash on trace it back to the controller. The injectors and coils are all powered with battery+ by the same circuit thru the ASD relay, so your probably good there( if it were bad you would likely loose the rest of the bank not just one cylinder.) So concentrate on the grounding/control driven by the PCM. For the Injector on cyl# 7 the 18Ga. Violet wire runs to the driver on connector #2 pin #2 (Second connector from the left on the PCM plastic will be white when unplugged). OHM out the wire and look at the terminal to be sure it isn’t corroded, damage or backed out. For the ign. coil the control wire goes to connector #2 pin#7, it is a Dark green w/orange stripe. Perform the same diagnostics as above. Take a look at the weather pack seal that is on the PCM connector; look for any tears or cuts that might let moisture in.
To answer your questions above, no a cam sensor won’t cause a single cylinder misfire. Yes, a bad driver in the PCM can cause a cylinder to drop out (Along with a short to power or ground in the control wire). If this is a consistent misfire that never goes away and your mechanic can’t find it with his own abilities and the information everyone had provided here…time to take it to another shop.
 
#12 ·
Leak down requires a dedicated tool that measures air flow %. The cylinder that is to be checked is brought up to top dead center(preferably using a dial indicator). An air hose from the tool is threaded into the spark plug hole. Shop air (60-100psi depending on tool brand) is applied. The tools gage indicates the percentage of air flow moving through the cylinder. Generally your looking at anywhere from 2% - 15% on a good engine. As the percentage increases higher a process of elimination needs to be used to determine the cause of the high leak rate. Typical causes are: (1)exhaust valve not seating(burnt valve, distorted valve seat or broken spring) (2)Intake valve not seating (carbon deposits or broken spring) (3)Leakage past piston into crankcase (worn cylinder bore, weak or broken piston rings, or even a piston with a hole burned thru it if cylinder ran lean). If leak down and compression are equal across all of the engines cylinders, then the problem is most likely electrical or fuel related.
 
#13 ·
i think i'm going to try a new injector in #7 and see if it does it and if it does not then i think the big D is going byebye and i will see if i can get a megacab but i hope the injector will fix it .i do not like thinking about new trucks yet $$$
 
#14 ·
what is the diff of a compression test to a leak down test ?
do thay not tell you the same thing ?
at this time i'm looking at the injector side so i'm trying TKO injector cleaner ,,,,, i think the injector is going nfg and needs to be replaced
 
#15 ·
Cylinder #7 misfire

I have an 01' with the same issue! I let a local superstore change the oil in my truck and ever since then the engine light has been on with a code P0307. Shortly after that it started to make a ticking noise like a clock. Being a misfire code, we changed plugs to split-fire platinums.Re-set cpu and within minutes it was back with the same code. Then changed the coil over #7. Same issue. Moved coils around,checked gaps on plugs. Once again got code P0307. Changed fuel injector for poops and hahas. Still no fix. Even went as far as to change the Throttle Position Sensor and PCV valve. Still says #7 misfire.AARRGGHH!!!!!
Another member of this forum said his started ticking after a quicky places' oil change also. He said that he ran "sea-foam" through the oil for an hour. Then changed the oil himself and replaced a "lash adjuster". He hasn't had a tick in over a year. Guess what I am doing this weekend!. Drop me a line and I will let you know if it gets rid of the P0307 code once and for all!!!!
 
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