92 F150 jumping/bucking intermitently
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3rd Gear
Joined: Jan 2023
Posts: 3
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92 F150 jumping/bucking intermitently
Hey all- first post
92 f150 5.0 5 speed 4x4
204,000 miles
About 2 months ago my truck started kind of bucking and intermittently misfiring it seemed. I started with intake manifold gasket after my mechanic hooked it up to his fogger. The engine was much more powerful after that, but still occasionally bucked, only when it was warm, which I found interesting. After that, I did the rotor, cap, plugs, and wires with no improvement. Checked codes, it was only putting out code 35 for a while (EGR valve position sensor out of range, high) so I started looking at the EGR system. Had old cracked vacuum lines, those are ALL replaced with no change. Did voltage testing and resistance testing on the EVP. Had 5v going to it, and 5000 ohm resistance with no vacuum, and decreased as vacuum was added. That all seemed okay according to the manual. Today I replaced EGR and EVP with no change, I think I will return those new parts. It is now putting out codes 31 (EGR valve position (EVP) sensor out of range (low) AND 35 (EGR valve position sensor out of range, high) this seems ridiculous to me, how is the signal too low and too high? Any advice would be much appreciated. Thanks in advance.
Video attached. Some days I can drive for 10 mins without this happening, then once it comes on it does not leave.
92 f150 5.0 5 speed 4x4
204,000 miles
About 2 months ago my truck started kind of bucking and intermittently misfiring it seemed. I started with intake manifold gasket after my mechanic hooked it up to his fogger. The engine was much more powerful after that, but still occasionally bucked, only when it was warm, which I found interesting. After that, I did the rotor, cap, plugs, and wires with no improvement. Checked codes, it was only putting out code 35 for a while (EGR valve position sensor out of range, high) so I started looking at the EGR system. Had old cracked vacuum lines, those are ALL replaced with no change. Did voltage testing and resistance testing on the EVP. Had 5v going to it, and 5000 ohm resistance with no vacuum, and decreased as vacuum was added. That all seemed okay according to the manual. Today I replaced EGR and EVP with no change, I think I will return those new parts. It is now putting out codes 31 (EGR valve position (EVP) sensor out of range (low) AND 35 (EGR valve position sensor out of range, high) this seems ridiculous to me, how is the signal too low and too high? Any advice would be much appreciated. Thanks in advance.
Video attached. Some days I can drive for 10 mins without this happening, then once it comes on it does not leave.
Logistics Pro
Joined: Nov 2013
Posts: 3,928
Likes: 1,198
From: Mojave, Ca
It's common failure on these trucks? Do you notice your dash lights flicker or your other needles move slightly when it cuts out?
Another common problem is the terminal on the ignition coil loosen up and start arcing and the spark drops out for a second. It's an easy thing to check.
THis guy had a similar problem. You can download the video he posted. https://www.ford-trucks.com/forums/1712258-shudder-skip-2.html
He made another thread that you can review. He said he replaced the coil and it fixed it. https://www.ford-trucks.com/forums/1712028-crank-no-start-again.html
Another common problem is the terminal on the ignition coil loosen up and start arcing and the spark drops out for a second. It's an easy thing to check.
THis guy had a similar problem. You can download the video he posted. https://www.ford-trucks.com/forums/1712258-shudder-skip-2.html
He made another thread that you can review. He said he replaced the coil and it fixed it. https://www.ford-trucks.com/forums/1712028-crank-no-start-again.html
Lead Driver
Joined: Oct 2016
Posts: 6,185
Likes: 633
From: Houston/Sugar Land
It's common failure on these trucks? Do you notice your dash lights flicker or your other needles move slightly when it cuts out?
Another common problem is the terminal on the ignition coil loosen up and start arcing and the spark drops out for a second. It's an easy thing to check.
Another common problem is the terminal on the ignition coil loosen up and start arcing and the spark drops out for a second. It's an easy thing to check.
Thread Starter
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3rd Gear
Joined: Jan 2023
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Worked on it most of the day testing assorted vacuum and electrical connections. All seemed okay. I have now replaced all vac lines, EGR valve, EGR position sensor, and EGR vac solenoid. At one point today I was able to clear all codes, and once again it ran well for 10 mins or so. I was also able to perform a running test for EEC, which pulled codes 77 (Wide open throttle not sensed during self test) and 52 (Power steering switch open circuit). Not sure if these are related. At various points throughout today I pulled codes 31, 33, 34, 35, ALL EGR related. I am really struggling understanding how the system is not working when every part of it is brand new and seems to be functioning (obviously something isn't). After I replaced the EGR vac solenoid it ran the worst it has ever ran. I was frustrated and had to call it a day.
Prototypemech- I see what you are saying, but I am not really having any of those symptoms. Just the tach is jumping, nothing else gives out even for a split second. Perhaps I will try replacing ignition switch and coil for the hell of it.
Prototypemech- I see what you are saying, but I am not really having any of those symptoms. Just the tach is jumping, nothing else gives out even for a split second. Perhaps I will try replacing ignition switch and coil for the hell of it.
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Logistics Pro
Joined: Nov 2013
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From: Mojave, Ca
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