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1991 e-150 351w 5.8L..Van is my home, which is great, except there is an acceleration issue.
Issue:The problem is intermittent, 99% of time it only happens in hot weather the engine will surge in rpm, very high, and stay there until I force it down by staccato hitting the pedal, or managing to side of road and turning engine off. When this happens it feels like the pedal is “catching” and not moving freely.
First mechanic...It needs a tune up...replaced plugs, wires. Van ran better over all, bit Still the surging.
Second mechanic...It is your fuel filter (This dx was made when I was having the fuel selector valve removed because prior owner removed one of the tanks but not the selector. Mpg got better, but surging still.
Third mechanic..Throttle body needs to be cleaned..overall performance improved, mpg got a bit better, surging still.
Fourth mechanic..You have a vacuum leak..replaced a hose..no difference in any way.
Fifth mechanic: It is this return spring..This made the acceleration and deceleration MUCH better, I actually thought the issue was solved. But two days later, surges and sticks again.
I can’t remember which mechanic, but one of them said they tested the tps and the voltage regulator and those were fine..but idk if they did. It is obd1 and it Only returns a code saying I didn’t do the “goose test”..then I did the goose test and it returned a code saying my coolant was out of range, it was in fact low so I assume the OBD is functioning in some way.
I have spent 600-700 dollars on the above listed, I do think they all needed to be done regardless so that is all good..I just really want to fix the surging, it is scary as ****.
Any suggestions?
 

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Welcome to the FFO!

Looking for some clarity
Surging = change in engine RPM OR vehicle speed with NO change in throttle (accelerator pedal) position
Or
Sticking ... is the accelerator pedal or linkage binding or hanging up in the travel?

The above are two very different situations. And may be you have both.

If the engine is surging, when does this happen? What vehicle speeds
And surging is an engine operating issue. Many time from the lack of maintenance.
How many miles on the vehicle?
Has the air filter and crankcase filter been replaced in the last year?
(This is one you can do yourself if the answer is no)
Have the oxygen sensors been replaced?

The sticking throttle is a mechanical thing. Either some thing has bent or has worn out OR there is something else interfering with the throttle linkage.

Sounds like all of the work was needed. It is just that work did not address the concern. And with the exception of the spring everything else is maintenance. So the vehicle may have been lacking in maintenance.

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Discussion Starter #4
Welcome to the FFO!

Looking for some clarity
Surging = change in engine RPM OR vehicle speed with NO change in throttle (accelerator pedal) position
Or
Sticking ... is the accelerator pedal or linkage binding or hanging up in the travel?

The above are two very different situations. And may be you have both.

If the engine is surging, when does this happen? What vehicle speeds
And surging is an engine operating issue. Many time from the lack of maintenance.
How many miles on the vehicle?
Has the air filter and crankcase filter been replaced in the last year?
(This is one you can do yourself if the answer is no)
Have the oxygen sensors been replaced?

The sticking throttle is a mechanical thing. Either some thing has bent or has worn out OR there is something else interfering with the throttle linkage.

Sounds like all of the work was needed. It is just that work did not address the concern. And with the exception of the spring everything else is maintenance. So the vehicle may have been lacking in maintenance.

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It does both. sometimes From full stop the pedal feels like it is catching, that is gone since the spring was changed. The rpm increase does not change the position of the pedal. When it is happening I can even pull the pedal all the way up and it is still revving. The only thing that will stop the rpm increase is stomping on the pedal or turning the engine off for at least 30 seconds. This happens at idle, with initial acceleration from idle, when downshifting into first on deceleration, or when attempting to drive under 10 mph. It does not happen once I am traveling In 2nd or 3rd. The vehicle was very poorly maintained. My guess is 160k very possibly 260k. I had to replace all the air filters and housing to pass emissions, but the crankcase filter I did not replace. No oxygen sensors have been replaced my be, so I ass7me they are the original ones, the prior owner must have been sentimentally attached to the OE so he never changed anything...ever, not once, lol.
 

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It does both. sometimes From full stop the pedal feels like it is catching, that is gone since the spring was changed. The rpm increase does not change the position of the pedal. When it is happening I can even pull the pedal all the way up and it is still revving. The only thing that will stop the rpm increase is stomping on the pedal or turning the engine off for at least 30 seconds. This happens at idle, with initial acceleration from idle, when downshifting into first on deceleration, or when attempting to drive under 10 mph. It does not happen once I am traveling In 2nd or 3rd. The vehicle was very poorly maintained. My guess is 160k very possibly 260k. I had to replace all the air filters and housing to pass emissions, but the crankcase filter I did not replace. No oxygen sensors have been replaced my be, so I ass7me they are the original ones, the prior owner must have been sentimentally attached to the OE so he never changed anything...ever, not once, lol.
This is on a Mustang but yours would be the same when you have very High Rpm
This talks about the transmission but pay attention to the bushing on it
It was my problem on a 91 Bird
 

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The oxygen sensors may not be working well. Replacement is highly recommended. Oxygen sensors do not trip the check engine light unless they have totally stopped working. Poorly working oxygen sensors will cause the engine to operate poorly at times and the computer thinks all is good because there is a signal. This can cause surging. Not guaranteed that is an issue for your application. And all oxygen sensors should be replaced every 100,000 miles. Your truck has at least 2. They are cheap and can be bought on line for under $20 each. I have replaced them on that same application (90 E 150 with 5.8l) and they are easy to replace.

Increasing engine RPM with constant accelerator position is a totally different problem. So you may have 3 problems.

1) The pedal sticking in a position is mechanical. Something is worn or binding. Only a physical inspection will find that one. And certain things may have to happen to find it. This situation usually gets worse with more use.

2) Surging or engine RPM changing up and down with the same pedal position is a air/fuel mixture problem. The computer is making changes based on data and goes too far then has to correct back to the original RPM. This is usually a vacuum leak or O2 sensors that are old and still working. The O2 sensor(s) tell the processor (computer) how the air fuel mixture is coming out the engine. When they get old the signal slows. So the computer is making adjustments based on old data. And that becomes a see saw ride that may not end.

3) Increasing engine RPM with constant pedal position is usually due to a vacuum leak. Engine RPM always goes UP when a vacuum leak occurs. And that vacuum leak may only occur under certain circumstances. (Engine temp or shifting vacuum hose or ???)

Lastly you stated you had to repair the housing. For the air filter??? The engine control system monitors all air coming in and exhaust going out. IF air is getting into the engine that is not measured, the system makes adjustments that are not correct. The incorrectness is air getting to the engine that is not accounted for. So the air cleaner and hoses to the throttle body HAVE to be securely connected. In that application there are two large rubber hoses from the air cleaner to the throttle body. Make sure these are well connected. (They are not the easiest to connect)

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Discussion Starter #7
This is on a Mustang but yours would be the same when you have very High Rpm
This talks about the transmission but pay attention to the bushing on it
It was my problem on a 91 Bird
I have intermittent hard jerky shifting as well, was that one of your symptoms too?
The oxygen sensors may not be working well. Replacement is highly recommended. Oxygen sensors do not trip the check engine light unless they have totally stopped working. Poorly working oxygen sensors will cause the engine to operate poorly at times and the computer thinks all is good because there is a signal. This can cause surging. Not guaranteed that is an issue for your application. And all oxygen sensors should be replaced every 100,000 miles. Your truck has at least 2. They are cheap and can be bought on line for under $20 each. I have replaced them on that same application (90 E 150 with 5.8l) and they are easy to replace.

Increasing engine RPM with constant accelerator position is a totally different problem. So you may have 3 problems.

1) The pedal sticking in a position is mechanical. Something is worn or binding. Only a physical inspection will find that one. And certain things may have to happen to find it. This situation usually gets worse with more use.

2) Surging or engine RPM changing up and down with the same pedal position is a air/fuel mixture problem. The computer is making changes based on data and goes too far then has to correct back to the original RPM. This is usually a vacuum leak or O2 sensors that are old and still working. The O2 sensor(s) tell the processor (computer) how the air fuel mixture is coming out the engine. When they get old the signal slows. So the computer is making adjustments based on old data. And that becomes a see saw ride that may not end.

3) Increasing engine RPM with constant pedal position is usually due to a vacuum leak. Engine RPM always goes UP when a vacuum leak occurs. And that vacuum leak may only occur under certain circumstances. (Engine temp or shifting vacuum hose or ???)

Lastly you stated you had to repair the housing. For the air filter??? The engine control system monitors all air coming in and exhaust going out. IF air is getting into the engine that is not measured, the system makes adjustments that are not correct. The incorrectness is air getting to the engine that is not accounted for. So the air cleaner and hoses to the throttle body HAVE to be securely connected. In that application there are two large rubber hoses from the air cleaner to the throttle body. Make sure these are well connected. (They are not the easiest to connect)

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This is essentially my first time owning a vehicle made after 1974 so the sensor thing is new to me. I am tempted to just replace all of them, the O2 and the tps and the speed and the one on the transmission..would this be stupid? I wish it was a carb I could just rebuild it and be done...all of this sensor computer stuff is making me nuts! Thank you so much for the advice, greatly appreciated.
 

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The oxygen sensors may not be working well. Replacement is highly recommended. Oxygen sensors do not trip the check engine light unless they have totally stopped working. Poorly working oxygen sensors will cause the engine to operate poorly at times and the computer thinks all is good because there is a signal. This can cause surging. Not guaranteed that is an issue for your application. And all oxygen sensors should be replaced every 100,000 miles. Your truck has at least 2. They are cheap and can be bought on line for under $20 each. I have replaced them on that same application (90 E 150 with 5.8l) and they are easy to replace.

Increasing engine RPM with constant accelerator position is a totally different problem. So you may have 3 problems.

1) The pedal sticking in a position is mechanical. Something is worn or binding. Only a physical inspection will find that one. And certain things may have to happen to find it. This situation usually gets worse with more use.

2) Surging or engine RPM changing up and down with the same pedal position is a air/fuel mixture problem. The computer is making changes based on data and goes too far then has to correct back to the original RPM. This is usually a vacuum leak or O2 sensors that are old and still working. The O2 sensor(s) tell the processor (computer) how the air fuel mixture is coming out the engine. When they get old the signal slows. So the computer is making adjustments based on old data. And that becomes a see saw ride that may not end.

3) Increasing engine RPM with constant pedal position is usually due to a vacuum leak. Engine RPM always goes UP when a vacuum leak occurs. And that vacuum leak may only occur under certain circumstances. (Engine temp or shifting vacuum hose or ???)

Lastly you stated you had to repair the housing. For the air filter??? The engine control system monitors all air coming in and exhaust going out. IF air is getting into the engine that is not measured, the system makes adjustments that are not correct. The incorrectness is air getting to the engine that is not accounted for. So the air cleaner and hoses to the throttle body HAVE to be securely connected. In that application there are two large rubber hoses from the air cleaner to the throttle body. Make sure these are well connected. (They are not the easiest to connect)

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Yes, the Air cleaner housing...someone had removed it all and replaced it with some aftermarket stuff. I had to put it back to original to pass emissions, so I replaced the air cleaner hoses, ho using and that thing on the end That clicks on. I got them from junkyard.
 

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Stupid? It depends on how you define the word.
Replacing the O2 sensor is maintenance.
The other items if bad would trip a check engine light. I assume the check engine light is not on or you would have stated that. If the check engine light is NOT on those other sensors should be good. It would not be stupid in my opinion. A waste of cash may be.

The vid in post #5 is for a car. That AOD transmission has different controls than the E4OD in trucks. The E stands for electronic and it is electronically shifted to OD. (Versus a cable)

Welcome to electronic engine controls. Where maintenance becomes more critical. For engines and control systems after 1980 the operation is different. When you get used to it you will appreciate it. I have a number of vehicles in my signature line that have none of that. However I do appreciate the newer engine systems and controls. But with out care and maintenance they become problems. Once you get ahead of the delayed maintenance it should be smoother sailing.

Speaking of maintenance, that E4OD will not last long if the fluid is not replaced every 30,000 miles. You can drain the torque convertor as well. This should be something like 20 quarts once drained. Then replace the filter screen too.

I drove my 90 E 150 5.8l with a E4OD for two decades. Had similar issues in the PO neglected it. Once I fixed everything including power window motors, clogged radiator and leaking heater core from extended cooling system service that truck ran well and was a work horse!!!! Because the PO did not change the coolant I over heated the engine and burned a valve. So I got the opportunity to replace heads, timing gears &chain and the oil pump. Not the prettiest vehicle on the block but for a 1/2 ton truck rated to tow 7500 pounds and it worked very hard and for a very long time after I got everything dialed in. I kind of miss it to this day.

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Stupid? It depends on how you define the word.
Replacing the O2 sensor is maintenance.
The other items if bad would trip a check engine light. I assume the check engine light is not on or you would have stated that.

The vid in post #5 is for a car. That AOD transmission has different controls than the E4OD in trucks. The E stands for electronic and it is electronically shifted to OD. (Versus a cable)

Welcome to electronic engine controls. Where maintenance becomes more critical. For engines and control systems after 1980 the operation is different. When you get used to it you will appreciate it. I have a number of vehicles in my signature line that have none of that. However I do appreciate the newer engine systems and controls. But with out care and maintenance they become problems. Once you get ahead of the delayed maintenance it should be smoother sailing.

Speaking of maintenance, that E4OD will not last long if the fluid is not replaced every 30,000 miles. You can drain the torque convertor as well. This should be something like 20 quarts once drained. Then replace the filter screen too.

I drove my 90 E 150 5.8l with a E4OD for a decade or so. Had similar issues in the PO neglected it. Once I fixed everything including power window motors, clogged radiator and leaking heater core from extended cooling system service that truck ran well and was a work horse!!!!

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The rear abs light is on, I should have mentioned that but it slipped my mind, sorry! No check engine lights, Intermittent hard shifting though. I replaced the transmission filter and fluid when I took ownership, it did not help the hard shifting, That was 3,000 miles ago. With the lack of maintenance it seems likely there could be multiple issues impacting the functioning. I am trying to catch up on the lapsed maintenance, it was unexpected, I purchased the vehicle from dealer out of state claiming 56k original miles...been fighting with them since day one, finally got some compensation back since it is CLEARLY not a low mileage vehicle. So maybe replace the 02 sensors and see if the issue resolves?
 

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Also, 2 transmissions shops have said there is nothing wrong with the transmission, the hard shifting is also intermittent. These phantom problems are driving me batty!
 

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It may be low mileage and not well maintained.
The O2 sensors may not make all the difference but should help.
After installing them you might disconnect the battery for 45 minutes. The system maintains a history of what is considered normal operation. Changing electronics does create a new normal and the system "relearns" what is normal. You can speed up that process by resetting the system. Can be done with a EEC IV tester if you have one. But disconnecting the battery is cheap and easy. (It does mess with the clock and radio pre-sets)

If the transmission doesn't smooth out in another 5 to 10,000 miles you might drain the fluid again. Use the correct fluid as well. Makes a difference.
When does the hard shifting occur? Between what gears and during what pedal position. (Light pressure, medium or WOT)

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It may be low mileage and not well maintained.
The O2 sensors may not make all the difference but should help.
After installing them you might disconnect the battery for 45 minutes. The system maintains a history of what is considered normal operation. Changing electronics does create a new normal and the system "relearns" what is normal. You can speed up that process by resetting the system. Can be done with a EEC IV tester if you have one. But disconnecting the battery is cheap and easy. (It does mess with the clock and radio pre-sets)

If the transmission doesn't smooth out in another 5 to 10,000 miles you might drain the fluid again. Use the correct fluid as well. Makes a difference.
When does the hard shifting occur? Between what gears and during what pedal position. (Light pressure, medium or WOT)

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Hard shifting is mostly confined to between 2nd and third, but will occasionally occur between first and second. 60% of the time it shifts perfectly and smoothly. The hard shifting seems to be more prevalent on inclines as is the Gutless in 3rd gear Issue. No exhaust restrictions have been found, the cat seems to be ok.
 

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Hard shifting is mostly confined to between 2nd and third, but will occasionally occur between first and second. 60% of the time it shifts perfectly and smoothly. The hard shifting seems to be more prevalent on inclines as is the Gutless in 3rd gear Issue. No exhaust restrictions have been found, the cat seems to be ok.
The pedal pressure does not seem to make a difference with the hard shift.
 

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All of those shifts are non-electronic.
Which may mean the valve body has some accumulation of varnish (A guess at this point) if servicing was delayed. Or clutch packs may have gotten burned. It may improve over time if the fluid is clean. May need to change the fluid a couple of times to get the valve body cleaned out or to get more debris out. Disassembly would be a solution however that is expensive and time consuming.

If it is this the shift will improve over time. Smelling the dip stick for a burnt smell will let you know heat is being generated. If that happens the fluid should be drained again.

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All of those shifts are non-electronic.
Which may mean the valve body has some accumulation of varnish (A guess at this point) if servicing was delayed. Or clutch packs may have gotten burned. It may improve over time if the fluid is clean. May need to change the fluid a couple of times to get the valve body cleaned out or to get more debris out. Disassembly would be a solution however that is expensive and time consuming.

If it is this the shift will improve over time. Smelling the dip stick for a burnt smell will let you know heat is being generated. If that happens the fluid should be drained again.

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Would I change the filter again also or jus5 change out the fluid?
 

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I have intermittent hard jerky shifting as well, was that one of your symptoms too?

This is essentially my first time owning a vehicle made after 1974 so the sensor thing is new to me. I am tempted to just replace all of them, the O2 and the tps and the speed and the one on the transmission..would this be stupid? I wish it was a carb I could just rebuild it and be done...all of this sensor computer stuff is making me nuts! Thank you so much for the advice, greatly appreciated.
Does your trans have an overdrive button on the shift lever?
They made an AOD and an E4OD trans in that year
 
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