E4OD Issue Help Needed

[TestDriver]

I've had this issue for a while now but it has gotten pretty severe. When my truck is slowing to a stop, my transmission (94 Turbo E4OD) seems to either not shift into a lower gear or let go of the converter lock up mechanism. It sometimes slows the engine to a stall. This also happens sometimes when I shift it into gear from park. It slows the engine down a lot and sometimes lets go or sometimes stalls it. The symptom came up first while shifting from drive into reverse.

It won't downshift easily either. Sometimes, I mash the pedal but it takes some 10 seconds to decide to downshift. I tried adjusting the sensor on the pump to see if it would downshift sooner but nothing changed.

My "off" light sometimes flashes but goes away. I thought it was a low fluid indication and added some but the level was not way too low and the flashing still happens and the symptoms are such that I've parked it.

I've rebuilt several AODs and understand the internals are similar to this thing with the valve body being the main difference. However, the symptoms don't lead me to any particular area that would be familiar to me.

Any help is appreciated.

 

[TestDriver]

From searching some more here, I have these this to add which might be pertinent.

My tach, when warm, will read erratically and drop to zero at idle.
My speedometer was working fine.

 

[flareside_thun]

That can affect your transmission's function entirely.

 

[LCAM-01XA]

Replace your tachometer sender, the PCM needs it to operate correctly. The sender is located on the IP gear housing, immediately next to the oil fill neck, and possibly partially hidden by your vacuum pump - it looks like a big hex nut with two wires coming out of it, and it takes 1" wrench to remove/install.

 

[TestDriver]

Replace your tachometer sender, the PCM needs it to operate correctly. The sender is located on the IP gear housing, immediately next to the oil fill neck, and possibly partially hidden by your vacuum pump - it looks like a big hex nut with two wires coming out of it, and it takes 1" wrench to remove/install.

Thanks. I'd done more searching and found one of your posts to some lady's tranny problems with a great breakdown of how the logic of the various sensors works. This had me thinking the tach sensor might be the issue but now I'll be sure to change it. I only have a used one available but at least, if it affects things, I'll know.

By the way, would the tach sensor going bad cause the tranny light to flash and how do I pull the codes?

 

[Compu Doc]

I just love it when someone says their tach is not working right and people chime in telling them right off the bat to replace their tach sender.

Suppose that is not the problem. The guy just spent a minimum of fifty for nothing. Make sure that your tach sender is bad to begin with before spending money to fix something that might not be broken.

1. Take a digital meter and set the meter to AC voltage of forty volts.

2. Disconnect tach sending unit from the plug.

3. Start truck

4 Measure the AC voltage on the wires coming out of the tach sender. Any reading of steady AC voltage the tach sender is fine. If no reading or erratic reading then replace tach sending unit.

5. To pull codes from the PCM take the truck to the nearest transmission shop. They will usually read the codes for free.

6. Make sure that you are reading the screen when they are pulling the codes.

7. In order to test the FIPL correctly the truck must be off with the ignition on and the throttle must be held down to the floor for thew entire test. If this is not done the FIPL will show as bad even though it may not be.

 

[trackspeeder]

If the converter is staying locked, there is a pressure problem, or internal leaks.

Try and grab the codes. That will make it a little easier to diagnose.

 

[TestDriver]

I just love it when...............................

5. To pull codes from the PCM take the truck to the nearest transmission shop. They will usually read the codes for free......................................

If the converter is staying locked, there is a pressure problem, or internal leaks.

Try and grab the codes. That will make it a little easier to diagnose.

That's just it. I don't think I can drive it to the nearest shop and they're probably closed now.

How do I pull the codes myself?

 

[TestDriver]

Never mind. I found the OBD1 plug under the hood by the brake booster and pulled the codes.

I have a soft 23 (FIPL sensor input out of self test range) code and two hard codes, 14 (RPM circuit - likely the tach pickup) and 43 (TPS or FIPL below idle speed) codes.

Lets see how the other tach sensor does. I know Compu Doc, the best way to test is to measure the sensor but at this point, it probably is the culprit. If this does not work, I'll certainly measure at least one of them.

I won't move the FIPL sensor since I had already moved it up but not reset the hard code. I'll post results.

 

['94IDITurbo7.3]

Never mind. I found the OBD1 plug under the hood by the brake booster and pulled the codes.

I have a soft 23 (FIPL sensor input out of self test range) code and two hard codes, 14 (RPM circuit - likely the tach pickup) and 43 (TPS or FIPL below idle speed) codes.

Lets see how the other tach sensor does. I know Compu Doc, the best way to test is to measure the sensor but at this point, it probably is the culprit. If this does not work, I'll certainly measure at least one of them.

I won't move the FIPL sensor since I had already moved it up but not reset the hard code. I'll post results.

Code 23= did not cycle the throttle while performaning the self-test. ie not stepping on gas pedal when pulling codes. No big deal though.

Code 43= probly the idle setting on the TPS is below spec.

 

[smolkin]

Your stalling problem sounds exactly like my sticky metering valve. I hope I'm not right but get your sensors squared away and I bet it still stalls. If so, copious amounts of additive and/or an IP shop are in your future.

 

[LCAM-01XA]

Thanks. I'd done more searching and found one of your posts to some lady's tranny problems with a great breakdown of how the logic of the various sensors works. This had me thinking the tach sensor might be the issue but now I'll be sure to change it. I only have a used one available but at least, if it affects things, I'll know.

By the way, would the tach sensor going bad cause the tranny light to flash and how do I pull the codes?

Stick the used sensor in place of what you have now, see if it changes anything. Whether it sets off codes, it may or may now - I had a tach sender fail long time ago, at idle my tach would read zero rpms, but the moment I got on the throttle even slightly it would come back to life and read accurately - never did set a code, or caused a blinky OD light, hell th PCM didn't even bother to raise the line pressure a bit, let alone actually enter any failure-management mode.

Compu Doc, IMHO there ain't no such thing as replacing a tach sender for nothing, unless the tach sender is brand new already - by now most of them things are running on borrowed time, hell my own one is like that cause it still works perfect but the wire insulation is pulling out of the sender's body. Also, in my experience the AC voltage test really don't really mean anything conclusive, and neither does the resistance one - when my old tach sender failed it passed both of these tests with flying colors, yet it still didn't work right at idle. Replaced it with another used sender I had pulled from a junker truck , problem went away. I now carry at least two known-good tach senders in my toolbox, in case what I currently run decides enough is enough while I'm somewhere in the middle of nowhere in say New Mexico...

 

[TestDriver]

Resolution.

Guys,

In the end, the tach sensor was bad. When I went to remove it, I noticed the PO had wrapped electrical tape to the wires as they come off the sensor. The tape had worked it's way up the wires and one of them showed the insulation was completely gone.

Also, the FIPL sensor was way off. It registered 0.52V at idle and 1.85 at WOT. I could not get it in range so I removed it and clocked it over the tab more before installing. After this, it was at 1.25V at idle and 3.8V at WOT.

I had installed this pump a couple of weeks ago. Now I wonder if I did damage to the transmission with the sensor being so far off. It ran great last night though. Shifts are a bit too early for my taste but at least it'll downshift good now and it does not stall the engine.

Time to work on other stuff like the multiple leaks the engine and tranny have. Check out my other thread here;

http://www.oilburners.net/forums/showthread.php?p=574149#post574149

Thanks again for all your help. I learned more things about the way these trucks work yesterday and it's always a satisfying feeling to do so.

 

[LCAM-01XA]

1.25V at idle, but what's your idle speed? The voltage specs are intended for the factory 650 rpm idle speed, so if you're actually idling at say 900 rpms and that's where you get the 1.25V, then your TPS voltage is still on the low side.

My idle speed is 650 rpms fully warmed up, my idle TPS voltage there is around 1.15V, and my upshift points are at 1900 rpms under very very light throttle (the egg between the foot and the throttle pedal), around 2200 rpms during light-moderate throttle (my usual driving style), and pedal to the floor gives me an upshift at right around 3500 rpms which is about 200-300 rpms before the overspeed governor in the IP kicks in.

That 3.8V WOT voltage, don't worry too much about it, it greatly depends on the swing of the IP throttle lever - some pumps have more swing than others do, it depends on their calibration I guess, so say both you and I set our idle voltages at 1.2V with both our IPs set to idle at 650 rpms, if my pump has more swing to its lever than yours I'll get a higher WOT voltage than you. So really, set your idle speed and idle voltage, then as long as your WOT voltage is between 3.5V and 4.3V you should be good to go.

 

[TestDriver]

1.25V at idle, but what's your idle speed? The voltage specs are intended for the factory 650 rpm idle speed, so if you're actually idling at say 900 rpms and that's where you get the 1.25V, then your TPS voltage is still on the low side.

My idle speed is 650 rpms fully warmed up, my idle TPS voltage there is around 1.15V, and my upshift points are at 1900 rpms under very very light throttle (the egg between the foot and the throttle pedal), around 2200 rpms during light-moderate throttle (my usual driving style), and pedal to the floor gives me an upshift at right around 3500 rpms which is about 200-300 rpms before the overspeed governor in the IP kicks in.

That 3.8V WOT voltage, don't worry too much about it, it greatly depends on the swing of the IP throttle lever - some pumps have more swing than others do, it depends on their calibration I guess, so say both you and I set our idle voltages at 1.2V with both our IPs set to idle at 650 rpms, if my pump has more swing to its lever than yours I'll get a higher WOT voltage than you. So really, set your idle speed and idle voltage, then as long as your WOT voltage is between 3.5V and 4.3V you should be good to go.

Yes, my idle is set high. I had moved it up because of the stalling situation. It's at about 1000rpm now. Since that is fixed, I plan on moving it back down but if the voltage setting drops below 1.1V at idle, I'll first evaluate if the shifting is good before I adjust it again.

These factory turbos are a pain to work on. It seems as if I have to remove the air cleaner housing to do just about any thing under the hood. This includes adjusting the FIPL sensor. And, this truck has a cow catcher on it which makes getting to anything more difficult. I need to cut that thing off.