McWillies
Member
- Joined
- Aug 30, 2017
- Messages
- 65
- Reaction score
- 16
- Points
- 8
- Age
- 25
- Location
- Louisiana
- Vehicle Year
- 1989
- Vehicle
- Ford Bronco II
- Engine Size
- 2.9l
- Suspension Style
- 4wd
I've had this issue for a while now, but I'm now getting around to digging into it. The problem is weird because it's not definite, but it is only under certain conditions... very specific conditions.
When the engine's cold, it starts up great. Start going down the road and all is well. Get on the highway and a few minutes in, once the engine is warmed up, I'll get a weird "jerk" around the speed it usually shifts into OD. To give an example; I'm going down the highway and then have to slow down to 55 or 60. When I go to speed back up, the truck sorta sputters/jerks. Almost like if it dies for half a second, comes back alive, dies again, so on and so forth. I can either give it more gas and it will power through (issues disappear at WOT) or I can manually shift it into 3rd (go from OD to D). When I'm in 3rd it doesn't happen at all at the same speeds. Continuing the story, I get off the highway and stop at the red light. While I'm sitting at the red light, it's trying to die on me and won't idle for shit, so I have to hold it at a higher RPM (I don't know what RPM because my tach doesn't work, but my foot is barely on the pedal, probably a few hundred over normal idle). The light turns green, I start to take off and the truck is sputtering and jerking, but only if I hold the RPMs at a normal rate and keep it constant (as you normally do when accelerating). If I give it some beans (more like a single bean, it's a 2.9 after all), the issues disappear.
Now let's talk about the starting with a misfire. I have a good example to share. I did some front end work on it recently after a wreck and needed to make it to an appointment at the alignment shop. I had to go down the highway to get there. The same issues I talked about before were happening (dies down at light, yada yada). Keep in mind it was hot as hell out, 90 degrees and sunny. Alignment tech jumps in and starts the truck and it does fine. Gets it on the rack and starts doing his thing (where I go they don't use the electronic stuff for alignments). Since they don't use the computers they make adjustments to get it close, take it for a drive to see how it feels, and come back to make more adjustments. First time he started it up to test drive, everything went fine. He drove it around for a minute, came back and made some adjustments. Second time, it wouldn't start. I could hear him cranking it and the first two or three times, it fired off, but it was really rough and died seconds later. Kept trying and after the fifth or sixth try it would just crank. Like I said before, I've been having these issues for a while so I know the little tricks to get it running. He opened up the door to the waiting room and told me it wouldn't start. I walked out there and told him to feather the gas pedal while it's cranking. Started up with a mean misfire, but he gave it some gas and it cleared up. Took it on the test drive, came back and did his thing, and from then on it started fine (I think he took it on two more test drives). When he was done and I went to leave, it started fine and I drove off.
Now to get to what I've done so far:
A couple months ago I replaced the MAP sensor, thinking that might be the issue. No dice.
The other day I had it in the shop to do the front brakes and decided to investigate this issue again. I remembered about two weeks ago, I got a CEL for a few minutes when it was happening, then it disappeared. Did a KOEO test to check for codes. All clear on hard faults with an 11, but I got a 41 from the continuous memory. Looked it up and that appears to be the O2 sensor. Ran to the parts store, got a new one, and threw it in. The old one had a Ford logo on it, not Motorcraft, so I can only imagine it was the same one as from the factory. Yesterday I drove it home (hour and a half mostly 60mph+). Same issue as far as the jerking when in OD, but it didn't seem to wanna die on me when I was stopped at a light after getting off the highway and when I stopped at the gas station and shut the truck off for a minute, it started back up fine. I also noticed that if I kept the speed about 69-70mph on the speedo (more like 72-73, tires are bigger than stock), it doesn't jerk when in OD.
-------------------------------------------------------------------
From what I've been able to interpret, it seems the jerking happens when I'm in a specific RPM range and the engine is warm, and it's just a coincidence that it always starts on the highway (any driving I do around town at low speeds is for a short amount of time).
I've read the TFI module can cause issues similar to this. When I was doing the O2 sensor I looked at the wires and they seemed fine. Felt around the back of the distributor and the TFI didn't feel melted or deformed.
When the engine's cold, it starts up great. Start going down the road and all is well. Get on the highway and a few minutes in, once the engine is warmed up, I'll get a weird "jerk" around the speed it usually shifts into OD. To give an example; I'm going down the highway and then have to slow down to 55 or 60. When I go to speed back up, the truck sorta sputters/jerks. Almost like if it dies for half a second, comes back alive, dies again, so on and so forth. I can either give it more gas and it will power through (issues disappear at WOT) or I can manually shift it into 3rd (go from OD to D). When I'm in 3rd it doesn't happen at all at the same speeds. Continuing the story, I get off the highway and stop at the red light. While I'm sitting at the red light, it's trying to die on me and won't idle for shit, so I have to hold it at a higher RPM (I don't know what RPM because my tach doesn't work, but my foot is barely on the pedal, probably a few hundred over normal idle). The light turns green, I start to take off and the truck is sputtering and jerking, but only if I hold the RPMs at a normal rate and keep it constant (as you normally do when accelerating). If I give it some beans (more like a single bean, it's a 2.9 after all), the issues disappear.
Now let's talk about the starting with a misfire. I have a good example to share. I did some front end work on it recently after a wreck and needed to make it to an appointment at the alignment shop. I had to go down the highway to get there. The same issues I talked about before were happening (dies down at light, yada yada). Keep in mind it was hot as hell out, 90 degrees and sunny. Alignment tech jumps in and starts the truck and it does fine. Gets it on the rack and starts doing his thing (where I go they don't use the electronic stuff for alignments). Since they don't use the computers they make adjustments to get it close, take it for a drive to see how it feels, and come back to make more adjustments. First time he started it up to test drive, everything went fine. He drove it around for a minute, came back and made some adjustments. Second time, it wouldn't start. I could hear him cranking it and the first two or three times, it fired off, but it was really rough and died seconds later. Kept trying and after the fifth or sixth try it would just crank. Like I said before, I've been having these issues for a while so I know the little tricks to get it running. He opened up the door to the waiting room and told me it wouldn't start. I walked out there and told him to feather the gas pedal while it's cranking. Started up with a mean misfire, but he gave it some gas and it cleared up. Took it on the test drive, came back and did his thing, and from then on it started fine (I think he took it on two more test drives). When he was done and I went to leave, it started fine and I drove off.
Now to get to what I've done so far:
A couple months ago I replaced the MAP sensor, thinking that might be the issue. No dice.
The other day I had it in the shop to do the front brakes and decided to investigate this issue again. I remembered about two weeks ago, I got a CEL for a few minutes when it was happening, then it disappeared. Did a KOEO test to check for codes. All clear on hard faults with an 11, but I got a 41 from the continuous memory. Looked it up and that appears to be the O2 sensor. Ran to the parts store, got a new one, and threw it in. The old one had a Ford logo on it, not Motorcraft, so I can only imagine it was the same one as from the factory. Yesterday I drove it home (hour and a half mostly 60mph+). Same issue as far as the jerking when in OD, but it didn't seem to wanna die on me when I was stopped at a light after getting off the highway and when I stopped at the gas station and shut the truck off for a minute, it started back up fine. I also noticed that if I kept the speed about 69-70mph on the speedo (more like 72-73, tires are bigger than stock), it doesn't jerk when in OD.
-------------------------------------------------------------------
From what I've been able to interpret, it seems the jerking happens when I'm in a specific RPM range and the engine is warm, and it's just a coincidence that it always starts on the highway (any driving I do around town at low speeds is for a short amount of time).
I've read the TFI module can cause issues similar to this. When I was doing the O2 sensor I looked at the wires and they seemed fine. Felt around the back of the distributor and the TFI didn't feel melted or deformed.