Engine runs rough at 1500 rpm, any ideas?
#17
03-30-2014, 02:52 PM
Join Date: Apr 2010
Location: Oak Harbor, WA
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mtbinva,
Sorry for the long delay. There are others FAR more knowledgeable than me on this subject and if you look further up the thread, JBREW provided a link to an article that FULLY explains the EGR system on the 5.4L Tritons. My problem has been much higher than idle, but others kept telling me that EGR problems are typically at ide and can practically stall out the engine from the valve being stuck open. Jbrew has some good troubleshooting methodology further up on my thread. Sounds like you have more of a fuel system related issue. Lack of pressure from a clogged fuel filter or a fuel pump that isn't putting out enough pressure. Test the fuel manifold pressure to make sure the injectors aren't being starved. Best of luck!
Sorry for the long delay. There are others FAR more knowledgeable than me on this subject and if you look further up the thread, JBREW provided a link to an article that FULLY explains the EGR system on the 5.4L Tritons. My problem has been much higher than idle, but others kept telling me that EGR problems are typically at ide and can practically stall out the engine from the valve being stuck open. Jbrew has some good troubleshooting methodology further up on my thread. Sounds like you have more of a fuel system related issue. Lack of pressure from a clogged fuel filter or a fuel pump that isn't putting out enough pressure. Test the fuel manifold pressure to make sure the injectors aren't being starved. Best of luck!
#18
03-31-2014, 12:06 AM
#19
03-05-2017, 10:24 PM
97 expedition 5.4 stumble at 1400 - 1500 rpm
I have a 98 Expedition 5.4L with 111K. Engine seems to run smoothly at idle and all rpms except just under 1500 once engine is warmed up. It doesn't show up when cold. As you slowly approach 1500, the motor starts to surge a bit and drop out/miss and then occilates as it catches itself. Once you push past it, it smooths out again.
No codes popped. Have replaced the PCV valve, repaired a vacuum leak from a burned out elbow way in the back (which seemed to fix, but the problem is back), replaced a throttle position sensor, and checked every vacuum line I could find for defects. I now have a very smooth running truck except at 1500.
It sounds like another vacuum leak, but I already fixed the common culprit of a burned out elbow against the firewall and all the other lines appear good.
Any ideas or quirks I'm missing? Up to now, the truck has run like a champ. Except for the parts mentioned above, the truck is completely stock.
Thanks.
No codes popped. Have replaced the PCV valve, repaired a vacuum leak from a burned out elbow way in the back (which seemed to fix, but the problem is back), replaced a throttle position sensor, and checked every vacuum line I could find for defects. I now have a very smooth running truck except at 1500.
It sounds like another vacuum leak, but I already fixed the common culprit of a burned out elbow against the firewall and all the other lines appear good.
Any ideas or quirks I'm missing? Up to now, the truck has run like a champ. Except for the parts mentioned above, the truck is completely stock.
Thanks.
#20
03-07-2017, 01:23 AM
Join Date: Apr 2010
Location: Oak Harbor, WA
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I never did find the problem with this issue. I had EXACTLY the same issue as you did. The PCM is sending a signal to the VAC valve to open the EGR. I even brought my truck into the Ford dealer a little over a year ago to have them figure it out and finally fix it. Everyone at the shop was at a total loss to explain it. They even called one of the technical engineers at Ford. There basically is no problem with the truck and from what the engineer said, he admitted that the PCM EGR mapping of the vehicle had some 'quirks'. They flashed the PCM with an updated the code which I was told should help. Unfortunately, it has made very little difference. I have had no choice but to simply accept it and put up with it. The truck is turning 20 this year with little else wrong with it. The only think I could suggest is to pay for one of those performance EPROM PCM upgrades that flashes The Whole system with updated mapping. Good luck. Let me know if you find anything else out, but you are not alone.
#21
03-10-2017, 03:29 PM
I never did find the problem with this issue. I had EXACTLY the same issue as you did. The PCM is sending a signal to the VAC valve to open the EGR. I even brought my truck into the Ford dealer a little over a year ago to have them figure it out and finally fix it. Everyone at the shop was at a total loss to explain it. They even called one of the technical engineers at Ford. There basically is no problem with the truck and from what the engineer said, he admitted that the PCM EGR mapping of the vehicle had some 'quirks'. They flashed the PCM with an updated the code which I was told should help. Unfortunately, it has made very little difference. I have had no choice but to simply accept it and put up with it. The truck is turning 20 this year with little else wrong with it. The only think I could suggest is to pay for one of those performance EPROM PCM upgrades that flashes The Whole system with updated mapping. Good luck. Let me know if you find anything else out, but you are not alone.
Thanks for the info. I had read your original post and thought I might have bought your old truck. Just kidding! My vehicle is a carbon copy of yours. No drive ability problems, just an issue that I would like to resolve. My wife tells me I have a problem because I keep looking for a solution to something that's not noticeable. She might be right but I'll keep digging.
Will keep ya all posted. Still waiting for a new TPS to be delivered.
#22
03-10-2017, 03:29 PM
#23
03-29-2017, 12:16 AM
This got stuck in the "reported post" section used to flag things for moderators attention.
I've copied it here into the thread. It seems like Jamone just pushed the wrong button when making the new post
