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Discussion Starter · #1 ·
‘91 E150. Ihave intermittent hard shifting between 1st and 2nd. Also when I get to third it almost immediately goes to fourth causing a bog down, is that OD? The dash switch for the OD is broken, has been since I purchased. Half the time it shifts smooth as can be, then wham! I have done a fluid/filter service. The IAC, TPS and O2 sensor have all been changed, just for FYI. I have a mechanic telling me I need a new transmission. When I asked him about changing the MLPS sensor he seemed unaware that it existed. Am I grasping at straws thinking it might be that part instead of an entire transmission? Also the trans fluid is still clean and not burnt etc., the service was done approximately 3,000 miles ago.
 

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How many miles on the vehicle?
Before the last transmission service, when was the one previous to that?
Does the speedometer work? If it has speed control does that work?
Is the check engine light on or any warning lights?

The Transmission lever position could be an issue however is not common.

That transmission is a variation of the C-6. The E4OD has four forward speeds and electronic shift controls replacing the hydraulic governor control mechanism of the C6. I am just not sure if all shifts are electronic. From 3 to OD (or 4th) IS electronic.
A broken OD button on the dash is an issue. Why are you not replacing that?

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Discussion Starter · #3 ·
How many miles on the vehicle?
Before the last transmission service, when was the one previous to that?
Does the speedometer work? If it has speed control does that work?
Is the check engine light on or any warning lights?

The Transmission lever position could be an issue however is not common.

That transmission is a variation of the C-6. The E4OD has four forward speeds and electronic shift controls replacing the hydraulic governor control mechanism of the C6. I am just not sure if all shifts are electronic. From 3 to OD (or 4th) IS electronic.
A broken OD button on the dash is an issue. Why are you not replacing that?

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Odometer read 56k when I got it, now it is 63k I assume this means 163k, I do not feel it can be less than that. With the state of the maintenance when I got it, there is no telling how long ago the prior transmission service was, but the old fluid was not burnt. The speedometer works. The only light on is the abs light. I want to replace the button, I have been unable to find one, also maybe mistakenly I was told not to worry about the button because the system would default correctly anyway. I was not that comfortable with that answer.
 

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I have replaced the button on a 1990 E 150. It is not easy to find! I bought an entire instrument bezel to get the switch.
Unique to Econoline and only for 1989 to 1991 models.

Here is one and it would be rather expensive to get. May be the seller would be willing to sell the switch or just the bezel (without the gauges) if you asked.
1987-1991 FORD ECONOLINE VAN INSTRUMENT CLUSTER SPEEDOMETER DASH BEZEL SURROUND | eBay

The ABS light is not related
As are the IAC, TPS and O2 will have little impact on shift quality.

If the issue was external to the transmission, transmission replacement may not fix.
The 3 to 4 shift will have a lot to do with that button.
The 1 to 2 shift does not.

For the 1 to 2 shift .... besides being harsh intermittently, is it early or about right for engine RPM?

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Discussion Starter · #5 ·
I have replaced the button on a 1990 E 150. It is not easy to find! I bought an entire instrument bezel to get the switch.
Unique to Econoline and only for 1989 to 1991 models.

Here is one and it would be rather expensive to get. May be the seller would be willing to sell the switch or just the bezel (without the gauges) if you asked.
1987-1991 FORD ECONOLINE VAN INSTRUMENT CLUSTER SPEEDOMETER DASH BEZEL SURROUND | eBay

The ABS light is not related
As are the IAC, TPS and O2 will have little impact on shift quality.

If the issue was external to the transmission, transmission replacement may not fix.
The 3 to 4 shift will have a lot to do with that button.
The 1 to 2 shift does not.

For the 1 to 2 shift .... besides being harsh intermittently, is it early or about right for engine RPM?

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It is shifting at the right time, and when it is not happening the shift is very nice and smooth. I read that hard shift from 1 to 2 is the limp mode for this, or is that not possible?
 

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If the PCM goes to LIMP mode the check engine light comes on and there other far more dramatic issues.

Recheck the transmission fluid level when the transmission is fully heated up.
Vehicle on level ground

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Discussion Starter · #7 ·
If the PCM goes to LIMP mode the check engine light comes on and there other far more dramatic issues.

Recheck the transmission fluid level when the transmission is fully heated up.
Vehicle on level ground

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If the PCM goes to LIMP mode the check engine light comes on and there other far more dramatic issues.

Recheck the transmission fluid level when the transmission is fully heated up.
Vehicle on level ground

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okay, I will do that. Thank you for the link to the dash part, I emailed the seller.
 

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That is how I bought my switch years ago.

Do post back as to the level. The transmission is sensitive to fluid type and level. Both under filled and over filled.
You have an intermittent shift issue, I want to rule out the cheap and easy stuff before spending money.

As to replacing the entire transmission, yeah that is just shooting a gun with eyes closed hoping to get dinner tonight

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Discussion Starter · #9 ·
That is how I bought my switch years ago.

Do post back as to the level. The transmission is sensitive to fluid type and level. Both under filled and over filled.
You have an intermittent shift issue, I want to rule out the cheap and easy stuff before spending money.

As to replacing the entire transmission, yeah that is just shooting a gun with eyes closed hoping to get dinner tonight

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I felt the same. These mechanics are so quick to say replace it, but until I am sure all the other elements are in working order it seems premature. This has been going on, on and off, for 7,000 miles. I wish I could find a good mechanic that can diagnose without obd2.
 

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A 91 is pre-OBDII. That is EEC IV.

EEC IV was a pretty good system. However by the early 1990s it had gotten pretty close to the limit of speed and memory.
Technically there was EEC V and beyond, however the Feds mandated OBDII that all manufactures have a similar diagnostics so techs did not need to know different systems from different manufactures

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Discussion Starter · #11 ·
That is how I bought my switch years ago.

Do post back as to the level. The transmission is sensitive to fluid type and level. Both under filled and over filled.
You have an intermittent shift issue, I want to rule out the cheap and easy stuff before spending money.

As to replacing the entire transmission, yeah that is just shooting a gun with eyes closed hoping to get dinner tonight

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I checked the fluid after driving a good bit. The level is good, no burnt smell, but the color is very light yellow not red.
 

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The type of fluid is stamped on the stick.
Pretty sure it is either Dexron III or Mercon
Both are redish in color.

Some other kind of fluid is going to give you issues.

Check the owner's manual or the transmission stick for the correct fluid type. You may be looking at a fluid flush

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