1993 f150 4.9 5 speed manual
Having bucking issues while accelerating. When I got the truck a month ago, it would only happen once in a while. Mainly on the highway and would just cut out for a few seconds then kick back on. I ignored it and it drove very nicely. No matter the load or rpm, it drove fine. Until a couple weeks ago it was cutting out again. I noticed the voltage gauge was going crazy. I noticed the bolts attaching the alternator case together were loose. I tightened the bolts and haven’t had an issue for a few weeks…. Until Yesterday, I started the truck and started driving and it would buck and the truck felt like it was struggling to get fuel or something. No voltage gauge issues this time. It was just bucking while accelerating and having trouble picking up speed. No codes other than 522, 565 when engine is off. And 30 while engine is running. I am at a total loss. I am thinking about removing EGR vacuum like and capping it to see if the issue comes back. I do have an exhaust manifold leak but no codes related to a o2 sensor issue.
Has anyone had an issue similar to this? And what should I test for first since it is intermittent?
Also 565 means canister purge solenoid issue. The smog pump has been removed. I’m not sure if this draws this code or not. Or does this even cause a bucking issue
Could the smog pump mess up oxygen sensor function? Part of the clean air is injected right at the exhaust manifold, upstream of the sensors, and more air comes down a pipe that goes in to the second catalytic converter from the top, making it harder to steal. That’s the 1996 OBD2 configuration anyway. Not sure the catalytic converter is the same in 1993.
I wonder if the capacitors in the ECU are failing. At 30 years a lot of those start drying up. The smaller ones first. The alternator problem made me think of this, since failing capacitors might make it more sensitive to Voltage fluctuation. It’s usually something that gets a little worse day by day or week by wee when they dry up. I like to change them before they fail in ECUs. Okay I just read on another site that yes there are capacitors and they fail and it causes problems like unstable idle and the check engine light never comes on.
My 1996 started stalling after being started, and then when put under load it would lose power for 1 second and then run well again for 1 second or so back and forth a few times for about 8 seconds as it slowly corrects itself. This happened at the same time as oxygen sensors failed and the fuel pressure regulator leaked in to the vacuum, so I thought it was related to that, but that was fixed. But if it’s not old gasoline then I think it is capacitors. It’s best to change them anyway.
The truck has an ECU, Airbag ECU, and ABS ECU, the radio (mine has stopped picking up any stations since 2023), and cluster. Only 5 things, and only one is critical for driving. Modern cars have 10+ with electric power steering that may not be so easy to access.
Now if you have any tips about the windshield water drain that goes down a passage that is in front of the door hinge pillar and built in to the cab and leaks water inside I would like that. It looks like they used wax like a toilet ring seal at the factory to seal this passage. It can only be accessed with long and narrow tools from the opening on top.