Rough Idle / Misfire on Cyl 6
05-29-2018, 06:38 PM
#1
Rough Idle / Misfire on Cyl 6 // SOLVED!!!
Once again, I have spent hours combing through page after page of forums and have found no definitive answer for what could be causing my specific problem.
My truck is a 2005 XLT 5.4 3v with just over 150k miles. I used to have a lot of problems with misfires when I would accelerate between 45 - 50 mph. I first solved this problem after getting a misfire code and replacing the COP on cylinder 8. After a few months the problem returned and I replaced all of the COPs. The truck again ran fine until a few months had passed and the misfire returned. I had a reputable mechanic replace the sparkplugs and decided that I would have him do the phasers, timing chains, tensioners, guides, etc at the same time. The truck ran great for almost a year after this.
The misfire slowly came back. By slowly I mean that I would occasionally get a miss when I was getting on the highway or going over an overpass. I tried to convince myself that it was nothing but I knew in the back of my mind that the problem was returning. I drove out to a vacation spot last weekend (a very hilly vacation spot) and as the truck was accelerating up a hill, the misfires came back worse than ever before. Now, the truck idles very rough, as in I can see the engine shaking when the hood is raised. It misfires badly anytime I try to accelerate to get on a highway. Or if the truck is on cruise control between 65 - 80 mph and I go over an overpass or small hill, it shutters badly. The misfire finally threw a code (P0306) which registered twice when I had the code pulled at Autozone.
A couple of other things I have noticed: the truck has trouble accelerating while driving over bumps/potholes etc. I don't drive over bumpy roads often so this never bothered me much but it is puzzling. Before I had the sparkplugs all changed, the misfire was made especially bad when I was pulling a trailer uphill. I assumed this meant that I fouled a plug. But this last weekend the misfire seemed to be caused by going up a hill again and the sparkplug on the offending cylinder looks fine to me.
I have replaced the injectors on cylinder 5 and cylinder 6 in an attempt to resolve the issue with no change. I pulled out the spark plugs on cylinders 5 and 6 to take a look at them and they look good (although I'm not totally sure that I know exactly what to look for to see if they're still good). I also plan on cleaning the MAF sensor, replacing the fuel filter, and changing the VCT solenoids. I have about a week to get the truck running right before I really need to use it.
Is there anything else I can do? I could spend a fortune replacing everything related to the engine. Let me know what y'all think!
My truck is a 2005 XLT 5.4 3v with just over 150k miles. I used to have a lot of problems with misfires when I would accelerate between 45 - 50 mph. I first solved this problem after getting a misfire code and replacing the COP on cylinder 8. After a few months the problem returned and I replaced all of the COPs. The truck again ran fine until a few months had passed and the misfire returned. I had a reputable mechanic replace the sparkplugs and decided that I would have him do the phasers, timing chains, tensioners, guides, etc at the same time. The truck ran great for almost a year after this.
The misfire slowly came back. By slowly I mean that I would occasionally get a miss when I was getting on the highway or going over an overpass. I tried to convince myself that it was nothing but I knew in the back of my mind that the problem was returning. I drove out to a vacation spot last weekend (a very hilly vacation spot) and as the truck was accelerating up a hill, the misfires came back worse than ever before. Now, the truck idles very rough, as in I can see the engine shaking when the hood is raised. It misfires badly anytime I try to accelerate to get on a highway. Or if the truck is on cruise control between 65 - 80 mph and I go over an overpass or small hill, it shutters badly. The misfire finally threw a code (P0306) which registered twice when I had the code pulled at Autozone.
A couple of other things I have noticed: the truck has trouble accelerating while driving over bumps/potholes etc. I don't drive over bumpy roads often so this never bothered me much but it is puzzling. Before I had the sparkplugs all changed, the misfire was made especially bad when I was pulling a trailer uphill. I assumed this meant that I fouled a plug. But this last weekend the misfire seemed to be caused by going up a hill again and the sparkplug on the offending cylinder looks fine to me.
I have replaced the injectors on cylinder 5 and cylinder 6 in an attempt to resolve the issue with no change. I pulled out the spark plugs on cylinders 5 and 6 to take a look at them and they look good (although I'm not totally sure that I know exactly what to look for to see if they're still good). I also plan on cleaning the MAF sensor, replacing the fuel filter, and changing the VCT solenoids. I have about a week to get the truck running right before I really need to use it.
Is there anything else I can do? I could spend a fortune replacing everything related to the engine. Let me know what y'all think!
Last edited by Southerner; 06-28-2018 at 10:26 AM. Reason: Solved
05-29-2018, 11:51 PM
#2
Once again, I have spent hours combing through page after page of forums and have found no definitive answer for what could be causing my specific problem.
My truck is a 2005 XLT 5.4 3v with just over 150k miles. I used to have a lot of problems with misfires when I would accelerate between 45 - 50 mph. I first solved this problem after getting a misfire code and replacing the COP on cylinder 8. After a few months the problem returned and I replaced all of the COPs. The truck again ran fine until a few months had passed and the misfire returned. I had a reputable mechanic replace the sparkplugs and decided that I would have him do the phasers, timing chains, tensioners, guides, etc at the same time. The truck ran great for almost a year after this.
The misfire slowly came back. By slowly I mean that I would occasionally get a miss when I was getting on the highway or going over an overpass. I tried to convince myself that it was nothing but I knew in the back of my mind that the problem was returning. I drove out to a vacation spot last weekend (a very hilly vacation spot) and as the truck was accelerating up a hill, the misfires came back worse than ever before. Now, the truck idles very rough, as in I can see the engine shaking when the hood is raised. It misfires badly anytime I try to accelerate to get on a highway. Or if the truck is on cruise control between 65 - 80 mph and I go over an overpass or small hill, it shutters badly. The misfire finally threw a code (P0306) which registered twice when I had the code pulled at Autozone.
A couple of other things I have noticed: the truck has trouble accelerating while driving over bumps/potholes etc. I don't drive over bumpy roads often so this never bothered me much but it is puzzling. Before I had the sparkplugs all changed, the misfire was made especially bad when I was pulling a trailer uphill. I assumed this meant that I fouled a plug. But this last weekend the misfire seemed to be caused by going up a hill again and the sparkplug on the offending cylinder looks fine to me.
I have replaced the injectors on cylinder 5 and cylinder 6 in an attempt to resolve the issue with no change. I pulled out the spark plugs on cylinders 5 and 6 to take a look at them and they look good (although I'm not totally sure that I know exactly what to look for to see if they're still good). I also plan on cleaning the MAF sensor, replacing the fuel filter, and changing the VCT solenoids. I have about a week to get the truck running right before I really need to use it.
Is there anything else I can do? I could spend a fortune replacing everything related to the engine. Let me know what y'all think!
My truck is a 2005 XLT 5.4 3v with just over 150k miles. I used to have a lot of problems with misfires when I would accelerate between 45 - 50 mph. I first solved this problem after getting a misfire code and replacing the COP on cylinder 8. After a few months the problem returned and I replaced all of the COPs. The truck again ran fine until a few months had passed and the misfire returned. I had a reputable mechanic replace the sparkplugs and decided that I would have him do the phasers, timing chains, tensioners, guides, etc at the same time. The truck ran great for almost a year after this.
The misfire slowly came back. By slowly I mean that I would occasionally get a miss when I was getting on the highway or going over an overpass. I tried to convince myself that it was nothing but I knew in the back of my mind that the problem was returning. I drove out to a vacation spot last weekend (a very hilly vacation spot) and as the truck was accelerating up a hill, the misfires came back worse than ever before. Now, the truck idles very rough, as in I can see the engine shaking when the hood is raised. It misfires badly anytime I try to accelerate to get on a highway. Or if the truck is on cruise control between 65 - 80 mph and I go over an overpass or small hill, it shutters badly. The misfire finally threw a code (P0306) which registered twice when I had the code pulled at Autozone.
A couple of other things I have noticed: the truck has trouble accelerating while driving over bumps/potholes etc. I don't drive over bumpy roads often so this never bothered me much but it is puzzling. Before I had the sparkplugs all changed, the misfire was made especially bad when I was pulling a trailer uphill. I assumed this meant that I fouled a plug. But this last weekend the misfire seemed to be caused by going up a hill again and the sparkplug on the offending cylinder looks fine to me.
I have replaced the injectors on cylinder 5 and cylinder 6 in an attempt to resolve the issue with no change. I pulled out the spark plugs on cylinders 5 and 6 to take a look at them and they look good (although I'm not totally sure that I know exactly what to look for to see if they're still good). I also plan on cleaning the MAF sensor, replacing the fuel filter, and changing the VCT solenoids. I have about a week to get the truck running right before I really need to use it.
Is there anything else I can do? I could spend a fortune replacing everything related to the engine. Let me know what y'all think!
06-01-2018, 09:08 AM
#4
05 5.4l 3v s.crew lariat
You have replaced a lot of parts, are they OEM
Non oem parts can haunt you . Never had any luck with aftermarket cops . Injectors work very hard I replace them all every 100k with new . After market phasers are a definite no-no . Some parts get ignored like spark boots they need changed each 60k when you change plugs. Misfires show up under load because you are climbing hill and in high gear -low rpm . It is still miss firing and slowly damaging cats when you don't feel it .
Ignition circuit must be perfect on these engines ,if done right it will last 60k . Off brand plugs ,dirty porcelain ,bad boots ,carbon build up around tip , old version plugs that crack easy or bad out of box , not using dielectric grease sparingly ,not cleaning cop contacts , clips on connectors not snapping on , not torque wrenching plugs in 25 to 28 foot pounds all add up . Get these right and this stuff will not happen .
Change that oil often ,get that carbon out of there . Change vcts if they are old style and have many miles on them. If you do timing job change tensioners to old type steel ratcheting type with no seals to blow out ,replace oil pump with new melling high volume 340hv . Make sure other parts are the latest . Use mc oil filter with good anti drain back valve.
Ignition circuit must be perfect on these engines ,if done right it will last 60k . Off brand plugs ,dirty porcelain ,bad boots ,carbon build up around tip , old version plugs that crack easy or bad out of box , not using dielectric grease sparingly ,not cleaning cop contacts , clips on connectors not snapping on , not torque wrenching plugs in 25 to 28 foot pounds all add up . Get these right and this stuff will not happen .
Change that oil often ,get that carbon out of there . Change vcts if they are old style and have many miles on them. If you do timing job change tensioners to old type steel ratcheting type with no seals to blow out ,replace oil pump with new melling high volume 340hv . Make sure other parts are the latest . Use mc oil filter with good anti drain back valve.
06-02-2018, 09:19 AM
#5
Non oem parts can haunt you . Never had any luck with aftermarket cops . Injectors work very hard I replace them all every 100k with new . After market phasers are a definite no-no . Some parts get ignored like spark boots they need changed each 60k when you change plugs. Misfires show up under load because you are climbing hill and in high gear -low rpm . It is still miss firing and slowly damaging cats when you don't feel it .
Ignition circuit must be perfect on these engines ,if done right it will last 60k . Off brand plugs ,dirty porcelain ,bad boots ,carbon build up around tip , old version plugs that crack easy or bad out of box , not using dielectric grease sparingly ,not cleaning cop contacts , clips on connectors not snapping on , not torque wrenching plugs in 25 to 28 foot pounds all add up . Get these right and this stuff will not happen .
Change that oil often ,get that carbon out of there . Change vcts if they are old style and have many miles on them. If you do timing job change tensioners to old type steel ratcheting type with no seals to blow out ,replace oil pump with new melling high volume 340hv . Make sure other parts are the latest . Use mc oil filter with good anti drain back valve.
Ignition circuit must be perfect on these engines ,if done right it will last 60k . Off brand plugs ,dirty porcelain ,bad boots ,carbon build up around tip , old version plugs that crack easy or bad out of box , not using dielectric grease sparingly ,not cleaning cop contacts , clips on connectors not snapping on , not torque wrenching plugs in 25 to 28 foot pounds all add up . Get these right and this stuff will not happen .
Change that oil often ,get that carbon out of there . Change vcts if they are old style and have many miles on them. If you do timing job change tensioners to old type steel ratcheting type with no seals to blow out ,replace oil pump with new melling high volume 340hv . Make sure other parts are the latest . Use mc oil filter with good anti drain back valve.
I have now replaced both vct solenoids with new ones, cleaned the MAF sensor, cleaned the throttle body, and replaced the air filter for good measure. I do have one cop wire plug that wont snap on and I can't figure out why. Other than that, I'm not sure what could be causing all of this especially since it was running great until I got in the hills. I'm going to take it to a mechanic on Monday to see if he can diagnose the problem. Then I'll fix the problem if I can afford to. Either way, I think I'm putting the truck up for sale next week. I'm jumping ship on this one, especially if the timing is f**ked up again. I've only driven the thing 10 or 15k miles since I did all the coils and plugs. Hopefully the mechanic can give me some direction.
06-02-2018, 11:28 AM
#6
LightningRod
@Southerner I think you might benefit from my long drawn out headaches with misfires. I'm now at over 230,000 and routinely run 50 to 70 OBDII drive cycles without the PCM registering a single misfire. I posted a long writeup here: https://www.f150forum.com/f12/ford-f150-2005-f150-stutter-dead-spot-rpm-drop-45-60-mph-u-load-167125/index4/#post4405407
Also, IMO - if you aren't getting timing codes - I believe you are getting by with the non-oem timing components.... FOR the time being. I would clean the carbon from the extended spark plug holes (beyond the threads), replace the plugs that have registered misfires (you can't see internal ceramic cracks), use ONLY NEW boots, and do a "hospital clean" spark plug job (without greasy finger prints on ANYTHING), and make sure the COP clips snap down. I think there's a 99% chance that will cure your misfires.
Also, IMO - if you aren't getting timing codes - I believe you are getting by with the non-oem timing components.... FOR the time being. I would clean the carbon from the extended spark plug holes (beyond the threads), replace the plugs that have registered misfires (you can't see internal ceramic cracks), use ONLY NEW boots, and do a "hospital clean" spark plug job (without greasy finger prints on ANYTHING), and make sure the COP clips snap down. I think there's a 99% chance that will cure your misfires.
06-02-2018, 04:20 PM
#7
@Southerner I think you might benefit from my long drawn out headaches with misfires. I'm now at over 230,000 and routinely run 50 to 70 OBDII drive cycles without the PCM registering a single misfire. I posted a long writeup here: https://www.f150forum.com/f12/ford-f150-2005-f150-stutter-dead-spot-rpm-drop-45-60-mph-u-load-167125/index4/#post4405407
Also, IMO - if you aren't getting timing codes - I believe you are getting by with the non-oem timing components.... FOR the time being. I would clean the carbon from the extended spark plug holes (beyond the threads), replace the plugs that have registered misfires (you can't see internal ceramic cracks), use ONLY NEW boots, and do a "hospital clean" spark plug job (without greasy finger prints on ANYTHING), and make sure the COP clips snap down. I think there's a 99% chance that will cure your misfires.
Also, IMO - if you aren't getting timing codes - I believe you are getting by with the non-oem timing components.... FOR the time being. I would clean the carbon from the extended spark plug holes (beyond the threads), replace the plugs that have registered misfires (you can't see internal ceramic cracks), use ONLY NEW boots, and do a "hospital clean" spark plug job (without greasy finger prints on ANYTHING), and make sure the COP clips snap down. I think there's a 99% chance that will cure your misfires.
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06-28-2018, 10:25 AM
#8
Alright, after months of dealing with this I finally found my issue. The valve cover was actually cracked on the bolt hole for the ignition coil retainer bolt on cylinder 5. I had to look very closely but that is definitely the reason for my misfire as the bolt would not tighten down enough to hold the coil in place. I fixed the problem by replacing the coil (I guess it went bad in the process of not making good contact with the plug?) and using a zip tie through the hole to keep it in place. If I really wanted to fix it right I’d have to pull the valve cover and replace it, which wouldn’t be bad, but I’m planning on selling the truck in the next couple of weeks anyway and it’s running great as is.
Now to figure out why why the brake warning light is always on! 😂
Now to figure out why why the brake warning light is always on! 😂
06-28-2018, 10:54 AM
#9
Mark
iTrader: (1)
pull the rear wheels and look at the release lever for the parking brakes... they get corroded and do not release correctly..
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Southerner (06-28-2018)
