High Idle then Surging.
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FTE Legend
Joined: Jun 2004
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From: Upstate NY
High Idle then Surging.
I have been trying to figure out what is going on with a '93 F150, 5.0, AOD, 4x4. Troubles stated a few weeks ago with some mild surging, quite mild. Then it went to High Idle. No KOEO codes, no CEL. I had been searching here for a clue and was starting to think it was the ECM. Took the truck to NAPA for parts for the wife's car the other day and when I came out of the store and started it, it began surging more obviously and the CEL came on. Got it home with noticeable performance loss, especially coming up our steep rough hill and parked. This morning I scanned it and got 23,10 and 53. Looks like classic TPS woes, Yes? I ordered a Motorcraft TPS and will try again when that arrives. This engine was completely rebuilt last summer about 2000 miles ago. It is driven occasionally. I replaced a lot of sensors as well as all the vacuum lines. Guess I should have replaced the TPS!
Logistics Pro
Joined: Mar 2005
Posts: 4,698
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From: Mexico, Missouri
If his truck is identical like my '92, F150. 4wd, AOD, 302, then it was 2 digit codes. Only my '92, F150, 4wd, M5OD, 300 had 3 digit codes. Have no idea why the I6 had 3 digit when the V8 had 2 digit codes. Both were bone stock, SD fuel.
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Joined: Aug 2021
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Based on your fault codes. TPS is on point.
My '95 F150 5.0 had similar symptoms but no fault codes and no surging while driving. Replaced the Idle Air Control Valve and the problem is gone.
'89 Mustang GT 5.0 also had similar issues with fault codes like yours, replaced the TPS with a Motorcraft part (instead of the auto parts generic) and the troubles went away.
I also read on the net that the coolant temp sensor and air charge temp sensor can also play into messing with the old ECUs. Not likely involved in this case, but you may have multiple issues present.
If your TPS is mounted on top of the throttle body, good for you. Mines on the bottom and difficult to get to. Throttle body appears to have to be removed for me. If you have that as well, while you are in there, check the condition of the IAC Valve. While your replacing the sensor check the condition of the terminals inside the connector, make sure there is no corrosion.
Good luck with it.
My '95 F150 5.0 had similar symptoms but no fault codes and no surging while driving. Replaced the Idle Air Control Valve and the problem is gone.
'89 Mustang GT 5.0 also had similar issues with fault codes like yours, replaced the TPS with a Motorcraft part (instead of the auto parts generic) and the troubles went away.
I also read on the net that the coolant temp sensor and air charge temp sensor can also play into messing with the old ECUs. Not likely involved in this case, but you may have multiple issues present.
If your TPS is mounted on top of the throttle body, good for you. Mines on the bottom and difficult to get to. Throttle body appears to have to be removed for me. If you have that as well, while you are in there, check the condition of the IAC Valve. While your replacing the sensor check the condition of the terminals inside the connector, make sure there is no corrosion.
Good luck with it.
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FTE Legend
Joined: Jun 2004
Posts: 31,920
Likes: 2,392
From: Upstate NY
Based on your fault codes. TPS is on point.
My '95 F150 5.0 had similar symptoms but no fault codes and no surging while driving. Replaced the Idle Air Control Valve and the problem is gone.
'89 Mustang GT 5.0 also had similar issues with fault codes like yours, replaced the TPS with a Motorcraft part (instead of the auto parts generic) and the troubles went away.
I also read on the net that the coolant temp sensor and air charge temp sensor can also play into messing with the old ECUs. Not likely involved in this case, but you may have multiple issues present.
If your TPS is mounted on top of the throttle body, good for you. Mines on the bottom and difficult to get to. Throttle body appears to have to be removed for me. If you have that as well, while you are in there, check the condition of the IAC Valve. While your replacing the sensor check the condition of the terminals inside the connector, make sure there is no corrosion.
Good luck with it.
My '95 F150 5.0 had similar symptoms but no fault codes and no surging while driving. Replaced the Idle Air Control Valve and the problem is gone.
'89 Mustang GT 5.0 also had similar issues with fault codes like yours, replaced the TPS with a Motorcraft part (instead of the auto parts generic) and the troubles went away.
I also read on the net that the coolant temp sensor and air charge temp sensor can also play into messing with the old ECUs. Not likely involved in this case, but you may have multiple issues present.
If your TPS is mounted on top of the throttle body, good for you. Mines on the bottom and difficult to get to. Throttle body appears to have to be removed for me. If you have that as well, while you are in there, check the condition of the IAC Valve. While your replacing the sensor check the condition of the terminals inside the connector, make sure there is no corrosion.
Good luck with it.
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FTE Legend
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From: Upstate NY
Finally got the Motorcraft TPS in the mail today. Pulled off the throttle body, scribed a line around the old TPS and put the new one back on and then replaced the gasket and put it all back together. I unhooked battery ground and cleared the codes while working on it. Started it up and it idled perfectly. Let it set there and think about it for a 10-15 minutes while I changed the registration sticker on the windshield and then took it for a test drive. Very smooth and even. I had gone to the junk yard this morning to get an old TPS harness segment to make a test point, so I could make any adjustments I might have to but this thing is running great. I shut it off and hooked up the Innova and got KOEO 11,10,11. I expected a little more fussing with it but not complaining.
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New User
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Finally got the Motorcraft TPS in the mail today. Pulled off the throttle body, scribed a line around the old TPS and put the new one back on and then replaced the gasket and put it all back together. I unhooked battery ground and cleared the codes while working on it. Started it up and it idled perfectly. Let it set there and think about it for a 10-15 minutes while I changed the registration sticker on the windshield and then took it for a test drive. Very smooth and even. I had gone to the junk yard this morning to get an old TPS harness segment to make a test point, so I could make any adjustments I might have to but this thing is running great. I shut it off and hooked up the Innova and got KOEO 11,10,11. I expected a little more fussing with it but not complaining.
As soon my belt tensioner arrives I'll be replacing that today or tomorrow. Undid the belt and spun the pulley on it because I started to hear a noise from that area. Feels like there is sand inside of it but it's a sealed bearing. Replaced the idler pulley when I changed the radiator because it was noisy. Didn't check the tensioner at the same time...silly me. Got 123.5K off the original.
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FTE Legend
Joined: Jun 2004
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From: Upstate NY
Excellent, glad to hear you have it fixed. Great idea to scribe the location of the current one before removing it.
As soon my belt tensioner arrives I'll be replacing that today or tomorrow. Undid the belt and spun the pulley on it because I started to hear a noise from that area. Feels like there is sand inside of it but it's a sealed bearing. Replaced the idler pulley when I changed the radiator because it was noisy. Didn't check the tensioner at the same time...silly me. Got 123.5K off the original.
As soon my belt tensioner arrives I'll be replacing that today or tomorrow. Undid the belt and spun the pulley on it because I started to hear a noise from that area. Feels like there is sand inside of it but it's a sealed bearing. Replaced the idler pulley when I changed the radiator because it was noisy. Didn't check the tensioner at the same time...silly me. Got 123.5K off the original.
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FTE Legend
Joined: Jun 2004
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From: Upstate NY
Since the holes in the TPS are larger than the machine screws that hold it on, there is an amount of play. I was making an effort to restore it to where it had been. If that dosen't matter then that is even easier! Thanks!
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I had a TPS sensor on the '89 GT that I bought aftermarket, it had two slots giving 2-3mm of play on each side instead of 2 holes with limited play. The instructions in the Chilton said to put the sensor in and adjust the position so that the signal was correct. I had to guestimate the proper orientation since I hadn't marked it. When i finally got a Motorcraft part for it, it had two holes with minimal play and I didn't feel it necessary to check anything, just put it on. But I was wishing the whole time I had marked the "factory" position. May not have been actual factory since the car's had at least 4 owners...but my truck, I know it is factory. Even if not necessary, I would do the same thing just in case it could have been or just in case I can't get a Motorcraft part at the time of repair.
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