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91 Explorer - Trans Won't Shift
- Thread starter azrael_ak
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- a4ld high idle transmission
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What about the trans kickdown cable? Nobody has mentioned this yet, could it be hanging up?
+1 on checking the vacuum line to the modulator. Also, check the vacuum "octopus" thing on the rear driver side of the upper intake manifold. Make sure all receptacles on it have either a line attached, or a rubber cap. Sometimes under hard acceleration the cap will blow off, or the vacuum line to the modulator will blow-
+1 on checking the vacuum line to the modulator. Also, check the vacuum "octopus" thing on the rear driver side of the upper intake manifold. Make sure all receptacles on it have either a line attached, or a rubber cap. Sometimes under hard acceleration the cap will blow off, or the vacuum line to the modulator will blow-
azrael_ak
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I am going to ramp it tonight and crawl under there to check the vacuum line to the trans. Wouldn't it not shift at all if it was leaking? The detent cable looks like its working fine.
We tested for vacuum leaks with carb clean the other night but couldn't find any. I replaced the TPS as well as the MAFS with no change other than the computer telling me that the error for the mass airflow sensor was fixed.
This morning the idle was 1100 and when i got home and put it in park the idle jumped to 2200 again.
This is extremely frustrating. The motor was just overhauled completely and I can't understand why it's doing this. The only thing I can think of now is the idle air control module i bought was defective. I bet it doesn't even have 2500 miles on it.
Does anyone know what the vacuum should be on the system while its running? I do have a vacuum gauge i could put on there.
malohnes
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My vacuum is at 20-21hg, at idle. Lemon replacement parts are not uncommon. I got 2 bum TPS's before, from different stores.
Reset your computer, disconnect bat for 15 minutes and connect and see if that has any effect.
Reset your computer, disconnect bat for 15 minutes and connect and see if that has any effect.
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VSS= Vehicle Speed Sensor.
It tells the ECM (Vehicles computer), when to shift the trans. It sets the shift points according to speed / acceleration. Yours is a mechanical driven gear with a cable attached to the speedometer in the dash, and the 2 wire ECM connector. This slides into the back of the transfer case, and is held on with a single 11mm bolt.
The gear on it meshes with a larger gear on the output shaft. We change the VSS gear to adjust our speedometer, and correct the shift points when we change tire diameter sizes. There are about 1/2 dozen sized gears, all a different color, for your rig. These gears spin the VSS shaft, and in turn do two things. 1) Spins the speedo cable to the dash cluster. 2) sends a pulse in voltage to the ECM. The faster you go, the faster the pulse signal. Newer models (97.5+ yrs) did away with this sensor, and use a tone ring in the rear differential, and shares the ABS sensor for the same information sent to the ECM. This is why those models have to have the speedo calibrated with a special electronic device, connected to the ECM.
I only suggested checking the voltage on it as another item to check off your test list, as it does play a part in the shifting system. I have had a couple go bad on me, so I know it's possible.
Another sensor that plays a part in vehicle idle, and how it runs, is the Temp sensor. When these go bad, it tells the ECM the wrong temps, and the wrong fuel air mixture, idle speed information is sent out. Some may think the engine is always cold, or always hot.
Your issue is two fold with no O/D & high idle after warming, so it's kind of hard to help on a forum. Normally if I had to answer each issue individually, I would say check the IAC & TPS besides the vac leaks. For the no O/D, I would say check the solenoid and/or the drum band. If the band broke, the clips are what break, and most of the time, they fall off into the pan. Easy to test that, by turning the tension bolt. Count the wrench turns inward, and see if it spins free with no resistance. If there is, turn it back the same amount of turns. Be easy on the bolt when doing this, as if the clip is still good, you can break it off yourself. You don't want to do that. lol
Maybe this guy can help if he sees this. Hey @NICE59FORDF100 , any ideas?
It tells the ECM (Vehicles computer), when to shift the trans. It sets the shift points according to speed / acceleration. Yours is a mechanical driven gear with a cable attached to the speedometer in the dash, and the 2 wire ECM connector. This slides into the back of the transfer case, and is held on with a single 11mm bolt.
The gear on it meshes with a larger gear on the output shaft. We change the VSS gear to adjust our speedometer, and correct the shift points when we change tire diameter sizes. There are about 1/2 dozen sized gears, all a different color, for your rig. These gears spin the VSS shaft, and in turn do two things. 1) Spins the speedo cable to the dash cluster. 2) sends a pulse in voltage to the ECM. The faster you go, the faster the pulse signal. Newer models (97.5+ yrs) did away with this sensor, and use a tone ring in the rear differential, and shares the ABS sensor for the same information sent to the ECM. This is why those models have to have the speedo calibrated with a special electronic device, connected to the ECM.
I only suggested checking the voltage on it as another item to check off your test list, as it does play a part in the shifting system. I have had a couple go bad on me, so I know it's possible.
Another sensor that plays a part in vehicle idle, and how it runs, is the Temp sensor. When these go bad, it tells the ECM the wrong temps, and the wrong fuel air mixture, idle speed information is sent out. Some may think the engine is always cold, or always hot.
Your issue is two fold with no O/D & high idle after warming, so it's kind of hard to help on a forum. Normally if I had to answer each issue individually, I would say check the IAC & TPS besides the vac leaks. For the no O/D, I would say check the solenoid and/or the drum band. If the band broke, the clips are what break, and most of the time, they fall off into the pan. Easy to test that, by turning the tension bolt. Count the wrench turns inward, and see if it spins free with no resistance. If there is, turn it back the same amount of turns. Be easy on the bolt when doing this, as if the clip is still good, you can break it off yourself. You don't want to do that. lol
Maybe this guy can help if he sees this. Hey @NICE59FORDF100 , any ideas?
azrael_ak
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Okay, Today while driving I got the idea to tap my brake pedal while doing 55.
As soon as i tapped it the vehicle's overdrive kicked off and the rpms went up accordingly. So... Is it possible to lose 4th gear and still have working OD?
I am going to look at changing those sensors you talked about... the temperature reporting sensor... and will look into testing the speed sensor.
Am going out right now to test the vacuum system with a new gauge I picked up.
As soon as i tapped it the vehicle's overdrive kicked off and the rpms went up accordingly. So... Is it possible to lose 4th gear and still have working OD?
I am going to look at changing those sensors you talked about... the temperature reporting sensor... and will look into testing the speed sensor.
Am going out right now to test the vacuum system with a new gauge I picked up.
azrael_ak
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Tonight I put a vacuum gauge on the main hub and it was -20-21. Sounds normal.
On the road today i was at 55mph and tapped the brake pedal and it kicked out of overdrive like normal. So I was mistaken, the OD is working. Is it possible that I just lost my highest gear?
My next questions are... Is it possible the tach is screwed up and giving me an incorrect reading? How do you test RPMs with a multimeter? My neighbor has the fancy one that can test rpms. But we need to know how.
Also. How do you go about testing the Speed sensor on the diff?
On the road today i was at 55mph and tapped the brake pedal and it kicked out of overdrive like normal. So I was mistaken, the OD is working. Is it possible that I just lost my highest gear?
My next questions are... Is it possible the tach is screwed up and giving me an incorrect reading? How do you test RPMs with a multimeter? My neighbor has the fancy one that can test rpms. But we need to know how.
Also. How do you go about testing the Speed sensor on the diff?
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You don't have a speed sensor on the rear, just an ABS sensor. Read my previous post again please.
Count the shifts as you climb in speed all the way to 60 mph or so. Or... while in Drive, doing 60 mph, watching the Tach, shift into OD while maintaining the same pressure on the skinny pedal. Does it shift into OD? Do the RPM's drop?
The trans should shift out of OD at higher speeds when you let off the gas, and back onto the gas. It will drop a gear, and RPM's will climb temporary until it shifts back into OD at your cruising speed. The only reason I say this, is to make sure your not thinking it's not working right.
Count the shifts as you climb in speed all the way to 60 mph or so. Or... while in Drive, doing 60 mph, watching the Tach, shift into OD while maintaining the same pressure on the skinny pedal. Does it shift into OD? Do the RPM's drop?
The trans should shift out of OD at higher speeds when you let off the gas, and back onto the gas. It will drop a gear, and RPM's will climb temporary until it shifts back into OD at your cruising speed. The only reason I say this, is to make sure your not thinking it's not working right.
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Actually, tapping the brake causes the torque converter to "unlock". The last "shift feel" to occur on a flat surface while climbing speed is the lockup. Overdrive comes first, then lockup.
You can turn overdrive off, and lockup will still occur in the lower "3rd" gear.
You can turn overdrive off, and lockup will still occur in the lower "3rd" gear.
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You are correct. 
my point though was that lockup is the last "shift feel" to occur and the first "downshift feel" when the brake is tapped. The TC needs to unlock before the actual downshift can occur. It also has to be unlocked while up shifting gears.
my point though was that lockup is the last "shift feel" to occur and the first "downshift feel" when the brake is tapped. The TC needs to unlock before the actual downshift can occur. It also has to be unlocked while up shifting gears.
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Yeah, that's what I was trying to say earlier, but your explanation is better. 
On my 1st gen, with it's 3rd A4LD in it, and with all of them, letting off the gas, unlocks OD TC lockup, at higher cruising speeds. I do not have to tap the brake for that to happen. It does not lock backup until I ease out of the throttle after resuming cruising speed. I know about the brake pedal unlocking it, and the OP had already stated it works, so I left it alone.
On my 1st gen, with it's 3rd A4LD in it, and with all of them, letting off the gas, unlocks OD TC lockup, at higher cruising speeds. I do not have to tap the brake for that to happen. It does not lock backup until I ease out of the throttle after resuming cruising speed. I know about the brake pedal unlocking it, and the OP had already stated it works, so I left it alone.
azrael_ak
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Okay.... It's been a few days of troubleshooting and replacing more parts. I took my friend to the hospital the other night and jumped on the freeway to get home and noticed that my rpms were the same no matter what speed i was doing. I think the stock tach spun itself out and its not right anymore.
I picked up a Equus from Schucks and installed it using the clip that goes over the spark plug wire but its not picking up. So i went back and they explained to me how that method usually never works due to the shielding in the wires and said I should either use the green wire and plug it into the distributor block or the tach test port. So that is what I am working on today.
I will post the results later on. Just driving around it doesn't really feel right. At 55 i take my foot off the gas and the rpms drop down to idle speed and if you put your foot back on the gas it almost slams it trying to get back up to speed.
I know it didn't do that before the incident.
I picked up a Equus from Schucks and installed it using the clip that goes over the spark plug wire but its not picking up. So i went back and they explained to me how that method usually never works due to the shielding in the wires and said I should either use the green wire and plug it into the distributor block or the tach test port. So that is what I am working on today.
I will post the results later on. Just driving around it doesn't really feel right. At 55 i take my foot off the gas and the rpms drop down to idle speed and if you put your foot back on the gas it almost slams it trying to get back up to speed.
I know it didn't do that before the incident.
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