Hey yall, new to this forum. Bought my 03 expy 5.4 4wd with 212k back in November. A few weeks ago, I started having a rough idle symptom, took it to a few people, all recommended to change 8 spark plugs and the coil pack on cyl 3 (the one that was pulling the misfire code) so did the job myself, used Bosch plugs, set the gap to .054 and were all torqued to about 13 ft lbs. started it back up, rough idle again, and now this time, the truck seemed to be going into limp mode, from a dead stop, the engine would either made clacking ish kinda noise and rev up super slowly, or it wouldn’t rev up at all past 1500 rpm, there also seems to be a knock as well, only in drive. The drivability issue is on and off, hooked my scan tool back up, showed no code for a misfire but gave me code p0353 ignition coil c primary or secondary circuit. Another thing that seems to be happening is my idle is idling at 2k rpm in park, then I shift it down into drive and it shudders and drops the rpm. Again, this issue it on and off aswell, but I did get a code last night for Throttle position sensor but I cannot remember the number. I know this a whole bunch of issues and sorry for any confusion but does anyone have any advice? Anyone with a similar issue and or fix? Get rid of it?
03 Expy 5.4 Rough idle & other symptoms
- Thread starter jalbert3v
- Start date
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whtbronco
Full Access Members
Well as you suggested I think there are or may be multiple issues here. Most may very well be related to the cylinder 3 coil, p0353. Intermittent issues usually lead me to initially suspect an electrical issue.
Did you replace the coil on cylinder 3? If so did you use a Ford coil to replace it? Have you checked the coil connector for cylinder 3 for corrosion?
I would recommend Motorcraft SP-479 spark plugs, but the Bosch plugs should be fine and clearly didn't change the issue. Did you find any ash, oil, damager or variation in wear on the old spark plugs?
This page seems to have a nice explanation and troubleshooting info for p0353:
bryansgarage.com
One other thought make sure the heater valve isn't leaking coolant. It sits right above cylinder 3 and caused me to have an intermittent misfire until I found it.
Did you replace the coil on cylinder 3? If so did you use a Ford coil to replace it? Have you checked the coil connector for cylinder 3 for corrosion?
I would recommend Motorcraft SP-479 spark plugs, but the Bosch plugs should be fine and clearly didn't change the issue. Did you find any ash, oil, damager or variation in wear on the old spark plugs?
This page seems to have a nice explanation and troubleshooting info for p0353:
Code P0353: Ignition Coil C Location - Clear Answer And Fix
Are you finding more information about the ignition coil c location? Let's learn more about code p0353 and where the ignition coil C is located in this writing!
bryansgarage.com
One other thought make sure the heater valve isn't leaking coolant. It sits right above cylinder 3 and caused me to have an intermittent misfire until I found it.
Vincent Vega
Full Access Members
Agree with @whtbronco, check the stuff he mentioned, starting with the spark plugs - they will tell you a lot. Usually misfires on Gen 2s are caused by bad coils, then people replace them with low quality aftermarket coils, which can be bad right out of the box. One way to double check that is swap the #3 coil with a different cylinder, and see if the misfire travels with that coil or not.
I would also check for vacuum leaks, and install a new fuel filter. The previous owners probably didnt replace the fuel filter enough, and after 20 years the vac hosing is at the age where it will fail.
Regarding the noise, get an automotive stethoscope to see if you can determine where the noise is coming from. On these, usually a noise like you are describing will come from the roller followers. Check #1 should be to see if the noise is coming from underneath the valve covers. If so, roller followers are often the reason, and will cause misfires if they get bad enough. Let us know what you find.
I would also check for vacuum leaks, and install a new fuel filter. The previous owners probably didnt replace the fuel filter enough, and after 20 years the vac hosing is at the age where it will fail.
Regarding the noise, get an automotive stethoscope to see if you can determine where the noise is coming from. On these, usually a noise like you are describing will come from the roller followers. Check #1 should be to see if the noise is coming from underneath the valve covers. If so, roller followers are often the reason, and will cause misfires if they get bad enough. Let us know what you find.
