2004 Rough Idle, Misfire, no codes?
#1
10-23-2015, 07:55 AM
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2004 Rough Idle, Misfire, no codes?
I'm left scratching my head over this one, I haven't been able to get a code from it even though the check engine light will flash when it happens.
The trucks having a bit of a rough idle, at least in my opinion its shaking. For whatever reason and it happens seemingly randomly, it will misfire so bad when I'm driving that it shakes the whole truck, you can hear stuff in the glove box bouncing and the whole 9 yards.... But when I put the code reader on it, it wont read any code and the misfire just goes away and it runs fine for days even weeks????
Anyone have any suggestions I was considering changing the coils but at $240 I'm not sure if that's the best starting point or even if its part of the problem.....
2004 f150 5.4 165k. 8 Plugs and 1 coil changed at 140k.
Thank you,
Ryan.
The trucks having a bit of a rough idle, at least in my opinion its shaking. For whatever reason and it happens seemingly randomly, it will misfire so bad when I'm driving that it shakes the whole truck, you can hear stuff in the glove box bouncing and the whole 9 yards.... But when I put the code reader on it, it wont read any code and the misfire just goes away and it runs fine for days even weeks????
Anyone have any suggestions I was considering changing the coils but at $240 I'm not sure if that's the best starting point or even if its part of the problem.....
2004 f150 5.4 165k. 8 Plugs and 1 coil changed at 140k.
Thank you,
Ryan.
#2
10-23-2015, 10:39 PM
Senior Member
I see several 'possibilities' in your symptoms. I am reading between the lines to an extent, but based on my own personal experience with an like vehicle and identical symptoms.
First (and MOST important), the flashing CEL is warning you that a catalyst damaging condition currently exists [ie: mixture far to fuel rich for the CAT to burn it all off without overheating and destroying itself. Once that condition passes - the CEL quits flashing. IF - the cause did not persist long enough to set a DTC the light goes back OFF. I describe it this way because, while OTHER factors can potentially cause flashing CEL (like an over-zealous/stuck injector) - but you mentioned misfires. Temporary Misfires WILL definitely result in flashing CEL. Therefore, I believe THIS is your cause.
Secondly: According to Motorcraft's OBDII Theory of Operation, another 'drastic' measure the PCM will take in an effort to SAVE its CATS from damage is to alternately SHUT DOWN the injectors & COPS on 1/2 of the cylinders to force limit the amount of unburned fuel getting to the CATS. THAT results in a horrible 4 cylinder like shaking that you describe as "shakes the whole truck, you can hear stuff in the glove box bouncing". I experienced this same symptom, and I believe THIS is happening in your case.
Thirdly: Your at 165K miles - and changed plugs @ 140, raising two questions. 1). how confident are you in the quality of the plug change? 2). have the O2's ever been replaced.
RELATING MY EXPERIENCE around 100-120k miles with identical symptoms. I did three plug changes - changed (ultimately all) COPS and more. Nothing made any difference until the third plug change coupled with an additional simple procedure. (See the post at https://www.f150online.com/forums/v8...ml#post5159499 ). (See also: http://www.f150forum.com/f4/5-4l-3v-...6/#post3930018 ) I believe you are going down the exact same path.
As a result of these experiences, I am an advocate of changing O2 sensors preventatively. Doing so on mine gave an increase in MPG and made a noticeable difference in live data for Fuel Trims. I believe they get "lazy" and lose calibration in the direction that results in the PCM "richening" the fuel mixture.
Following the maintenance detailed in the above links, I have buzzed right on up past 210,000 miles without ANY further misfire problems, limp mode ECL flashing, bucking, or random misfires.
First (and MOST important), the flashing CEL is warning you that a catalyst damaging condition currently exists [ie: mixture far to fuel rich for the CAT to burn it all off without overheating and destroying itself. Once that condition passes - the CEL quits flashing. IF - the cause did not persist long enough to set a DTC the light goes back OFF. I describe it this way because, while OTHER factors can potentially cause flashing CEL (like an over-zealous/stuck injector) - but you mentioned misfires. Temporary Misfires WILL definitely result in flashing CEL. Therefore, I believe THIS is your cause.
Secondly: According to Motorcraft's OBDII Theory of Operation, another 'drastic' measure the PCM will take in an effort to SAVE its CATS from damage is to alternately SHUT DOWN the injectors & COPS on 1/2 of the cylinders to force limit the amount of unburned fuel getting to the CATS. THAT results in a horrible 4 cylinder like shaking that you describe as "shakes the whole truck, you can hear stuff in the glove box bouncing". I experienced this same symptom, and I believe THIS is happening in your case.
Thirdly: Your at 165K miles - and changed plugs @ 140, raising two questions. 1). how confident are you in the quality of the plug change? 2). have the O2's ever been replaced.
RELATING MY EXPERIENCE around 100-120k miles with identical symptoms. I did three plug changes - changed (ultimately all) COPS and more. Nothing made any difference until the third plug change coupled with an additional simple procedure. (See the post at https://www.f150online.com/forums/v8...ml#post5159499 ). (See also: http://www.f150forum.com/f4/5-4l-3v-...6/#post3930018 ) I believe you are going down the exact same path.
As a result of these experiences, I am an advocate of changing O2 sensors preventatively. Doing so on mine gave an increase in MPG and made a noticeable difference in live data for Fuel Trims. I believe they get "lazy" and lose calibration in the direction that results in the PCM "richening" the fuel mixture.
Following the maintenance detailed in the above links, I have buzzed right on up past 210,000 miles without ANY further misfire problems, limp mode ECL flashing, bucking, or random misfires.
#3
11-08-2015, 01:03 PM
Join Date: Jun 2014
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I see several 'possibilities' in your symptoms. I am reading between the lines to an extent, but based on my own personal experience with an like vehicle and identical symptoms.
First (and MOST important), the flashing CEL is warning you that a catalyst damaging condition currently exists [ie: mixture far to fuel rich for the CAT to burn it all off without overheating and destroying itself. Once that condition passes - the CEL quits flashing. IF - the cause did not persist long enough to set a DTC the light goes back OFF. I describe it this way because, while OTHER factors can potentially cause flashing CEL (like an over-zealous/stuck injector) - but you mentioned misfires. Temporary Misfires WILL definitely result in flashing CEL. Therefore, I believe THIS is your cause.
Secondly: According to Motorcraft's OBDII Theory of Operation, another 'drastic' measure the PCM will take in an effort to SAVE its CATS from damage is to alternately SHUT DOWN the injectors & COPS on 1/2 of the cylinders to force limit the amount of unburned fuel getting to the CATS. THAT results in a horrible 4 cylinder like shaking that you describe as "shakes the whole truck, you can hear stuff in the glove box bouncing". I experienced this same symptom, and I believe THIS is happening in your case.
Thirdly: Your at 165K miles - and changed plugs @ 140, raising two questions. 1). how confident are you in the quality of the plug change? 2). have the O2's ever been replaced.
RELATING MY EXPERIENCE around 100-120k miles with identical symptoms. I did three plug changes - changed (ultimately all) COPS and more. Nothing made any difference until the third plug change coupled with an additional simple procedure. (See the post at https://www.f150online.com/forums/v8...ml#post5159499 ). (See also: http://www.f150forum.com/f4/5-4l-3v-...6/#post3930018 ) I believe you are going down the exact same path.
As a result of these experiences, I am an advocate of changing O2 sensors preventatively. Doing so on mine gave an increase in MPG and made a noticeable difference in live data for Fuel Trims. I believe they get "lazy" and lose calibration in the direction that results in the PCM "richening" the fuel mixture.
Following the maintenance detailed in the above links, I have buzzed right on up past 210,000 miles without ANY further misfire problems, limp mode ECL flashing, bucking, or random misfires.
First (and MOST important), the flashing CEL is warning you that a catalyst damaging condition currently exists [ie: mixture far to fuel rich for the CAT to burn it all off without overheating and destroying itself. Once that condition passes - the CEL quits flashing. IF - the cause did not persist long enough to set a DTC the light goes back OFF. I describe it this way because, while OTHER factors can potentially cause flashing CEL (like an over-zealous/stuck injector) - but you mentioned misfires. Temporary Misfires WILL definitely result in flashing CEL. Therefore, I believe THIS is your cause.
Secondly: According to Motorcraft's OBDII Theory of Operation, another 'drastic' measure the PCM will take in an effort to SAVE its CATS from damage is to alternately SHUT DOWN the injectors & COPS on 1/2 of the cylinders to force limit the amount of unburned fuel getting to the CATS. THAT results in a horrible 4 cylinder like shaking that you describe as "shakes the whole truck, you can hear stuff in the glove box bouncing". I experienced this same symptom, and I believe THIS is happening in your case.
Thirdly: Your at 165K miles - and changed plugs @ 140, raising two questions. 1). how confident are you in the quality of the plug change? 2). have the O2's ever been replaced.
RELATING MY EXPERIENCE around 100-120k miles with identical symptoms. I did three plug changes - changed (ultimately all) COPS and more. Nothing made any difference until the third plug change coupled with an additional simple procedure. (See the post at https://www.f150online.com/forums/v8...ml#post5159499 ). (See also: http://www.f150forum.com/f4/5-4l-3v-...6/#post3930018 ) I believe you are going down the exact same path.
As a result of these experiences, I am an advocate of changing O2 sensors preventatively. Doing so on mine gave an increase in MPG and made a noticeable difference in live data for Fuel Trims. I believe they get "lazy" and lose calibration in the direction that results in the PCM "richening" the fuel mixture.
Following the maintenance detailed in the above links, I have buzzed right on up past 210,000 miles without ANY further misfire problems, limp mode ECL flashing, bucking, or random misfires.
In that post they're describing multiple locations for the 02 sensors, which ones did you do or did you do all 4?
great post, Thank you for the help!
Ryan.
#4
11-08-2015, 03:03 PM
#5
11-08-2015, 06:21 PM
Senior Member
@glc is absolutely correct, the Front O2s are the ones that measure Fuel/Air ratio.
Actually, I changed all four of mine - and I think it is about $240.00 well spent every 100k or so. However I hope my question didn't mislead. Your O2s _ARE_ WORKING if your CEL flashes, and then clears. EXCESS, UNBURNED fuel is getting to your O2s, and they are reacting the proper way, although that doesn't mean they aren't 'lazy' or their reading is calibrated, but they ARE working.
Look for WHY unburned fuel is reaching your O2s. ??? Misfires - most likely-, Sticking injector(s) - perhaps, Intake leak - possibly contributing to rough idle the rough.
In my case - it was due to intermittent misfires that I had fought unsuccessfully for an extended period of time. All my O2s were replaced as part of that exercise.
Actually, I changed all four of mine - and I think it is about $240.00 well spent every 100k or so. However I hope my question didn't mislead. Your O2s _ARE_ WORKING if your CEL flashes, and then clears. EXCESS, UNBURNED fuel is getting to your O2s, and they are reacting the proper way, although that doesn't mean they aren't 'lazy' or their reading is calibrated, but they ARE working.
Look for WHY unburned fuel is reaching your O2s. ??? Misfires - most likely-, Sticking injector(s) - perhaps, Intake leak - possibly contributing to rough idle the rough.
In my case - it was due to intermittent misfires that I had fought unsuccessfully for an extended period of time. All my O2s were replaced as part of that exercise.
#6
11-18-2015, 10:08 AM
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#7
11-23-2015, 01:57 PM
