intermittent hesitation problem
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From: East Coast
I have to pass inspection, and this is my daily driver, so I'd like to keep the EFI all in working order. My truck just started last week with this. I changed both fuel filters, put in drygas, and filled the tank again. It seems a little better than it was. I'm going to see how it is after running some more, maybe I just got some bad gas, if not I'll have to take it into a shop 
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I replaced the Oxygen sensor, and it drives a whole lot better, although I'm still getting the code 31,10,and 11 now, whereas before I only gotten the 31, and then the 11....humm I didn't know there was a 10, at least it drives better at low speed without the shuttering. I had rebooted the computer after replacing the sensor. So I have to go an find out what the code 10 is for. I rather have the emissions connected also, has thats the way the engine was designed for.
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I just changed my O2 sensor about a month ago, and it was before it was giving me any problems. I'm getting the same codes now as I always do, it ran fine for a long time like that. I checked things out again. The vacuum to the egr seems ok, the egr and sensor are new, O2 sensor is new. I don't know what else it could be. 
I was hoping it was fuel related, because after the drygas and fuel filter it seemed a lot better, but after getting gas it's not much better. It accelerates better, but it still cuts out on me driving. My truck seems to be worse at slower speeds, like trying to accelerate in 3rd from 35 mph, I don't usually have to downshift, but that's when it seems to be giving me problems now.
I was hoping it was fuel related, because after the drygas and fuel filter it seemed a lot better, but after getting gas it's not much better. It accelerates better, but it still cuts out on me driving. My truck seems to be worse at slower speeds, like trying to accelerate in 3rd from 35 mph, I don't usually have to downshift, but that's when it seems to be giving me problems now.
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From: Right Next to U
Nickmobile67, Did you reboot the computer? I have found that rebooting the computer after a sensor or a part thats been replaced helps to reprogramm the computer for your new parts. I usually reboot after its been warmed, then drive it slow for a while, then speed up to 45 then slow down again to 25 to get it to change gears, I done it a few times and then drove for 30 miles to get it to learn its new parts again...doing the speed limits and the usually stop an go routine during the 30 mile run...Even stopping an letting it sit afterwards for about 10 min then setting the carb adjustment. You do that by letting it warm up to operating temp, then turning it off. undo the neg battery cable, within 3 min. Adjust the curb idle on the Throttle body screw, reconnecting the battery within the 3 min. Restart an let it idle. Repeat as necessary.This info came from a mech. Book on EFI engines from Ford. Hope this helps.
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Yes, after the sensor change I left the battery disconnected for probably 10 or 20 minutes. I then drove the truck to town and back, so I got a little smooth 50 mph driving, and some stoplights, all that, and the sensor change was about a month ago and I've driven the truck almost every day, but the problem just started last week.
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Even after the battery was disconnected I still got that damn code 31 (even with engine off test), along with some other bs code telling me the temporary memory was lost because of the battery. also, my meter gives me a steady code when the truck is shut off, what is that trying to tell me?
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From: Right Next to U
It will have the last code on screen for 30 sec or until you turn it off. To clear the codes from the tester, simply unplug the battery from the tester, then reconnect the battery to redo the test. I have the Digital one, and like it better than the blinking light one, from that one, I couldn't blink unless I would missed the code....To clear the memory on the truck computer, it should clear after 30 min, then you have to drive it doing all of the above for the computer to do its thing, with all the sensors, relearning your driving and the condition of the engine. If it doesn't clear after 30 min, try to clear it with the ignition on engine off, just turn the tester off will clear the RAM on the computer...according to the manual. SO far I am also still getting the 31 code, but also getting the 11 pass code after that,(KOEO) But it runs lots better an no more struttering and dieing when its moving. Doesn't die at all when its first started up.
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Before I put the scanner in test, when it's still in hold, and I put the key on, by the time I walk back to put the tester on I am already getting a steady code. What does that mean? I heard something about it signaling some sort of connection problem or something, but I don't know. I drove the truck to work today and it didn't give me any trouble. 
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From: Right Next to U
When you first decide to do the test, first turn ign on, walk back up front, turn the tester on, then press test, wait for results, wait 30 seconds after last test, turn tester off, walk back around to turn ignition off. post results.
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First, hello to all. Second, I am having the same problem with my 82 F150. I replaced the engine as it didn't run when I got it. Re-ran all of my vacuum lines (even had a shop check to see that I did it correctly). Rebuilt my carb. It is a 4.9L L-6. It idles beautifully, runs like a champ. But, when accelerating, it bogs down, then runs fine again. Today on the highway was the worst it has ever been. At 55-60, I mashed the pedal to the floor and it actually started losing speed. The engine was not making strange noises at all. I let off, went back to a regular driving position and it accelerated back to speed. It almost acts like a brake is constantly trying to slow it down. Like the other folks having the same issue, it is 1. not conistent, and 2. ANNOYING. I have replaced all the vacuum lines, rebuilt the carb and tomorrow will replace the vacuum switch, PCV, and take off the EGR to see what the deal is. Any help would be great.
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From: Right Next to U
Nick, remove the batteries and redo the test, make sure its in the on position before turning the ign on, then walk back around (not engine running but to on) press test then wait for results, after 30 sec. turn tester off, turn ign off, post code(s).
Percy, Sounds like the fuel pump is bad or fuel filter clogged, check filter near tank if you have one, if not put a clear inline filter on it before the carb. whenit boggs down stop, and go check filter to see if it has any in it. If not either of above, it could be ign. module problems.
Percy, Sounds like the fuel pump is bad or fuel filter clogged, check filter near tank if you have one, if not put a clear inline filter on it before the carb. whenit boggs down stop, and go check filter to see if it has any in it. If not either of above, it could be ign. module problems.