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Early 1999 F450 PTO setup.. remand trans but looks to be stock converter.. 4x2 cab and chassis.180k for miles.. this truck is stock no chip no upgrades. Just tires are larger 255/70/22.5.. Maintained Well.. . Trucks used as a hauler. Daily it will have two carS at a time. 22k 26klbs total weight with truck and payload. I’ve done a lot of work on this. there is so much on these to trouble shooting.. all my issues with out throwing money at it. I have fix.. all service engine problems are corrected.. no OD light flash besides Over temp happed a couple times.. I have a banks temp gauge on it now. I found last night my cooler and lines were cold. Has low line pressure said snap on scanner. This rig is acting identical to brake switch on ( brake peddle pressed ). I’ve done the 69 hit brakes and hold nothing happens. No change. If I hit the OD button it will down shift then go right back if I stay in same AP position. If I easily press a little more it will high rev. With a lot of converter slip. 3rd will hold steady with 100 converter lock unless I let off. Then it will try fourth again. If I run in drive. No issues. well besides the cooler not getting fed trans fluid. Well the low line pressure. 😕... I also have a leak in my fuel line don’t seem to effect engine, but as I’ve read can’t take nothing for granted.. so handling fuel leak tonight. Thank you all ahead of time..
 

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A scan tool cannot read line pressure. What exactly did it tell you?

My guess is that the check valve in the bypass has failed. Summit Racing offers a rebuild kit for this for about $25. It's really easy to install. Your symptoms are exactly that of a failed bypass.
 

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A scan tool cannot read line pressure. What exactly did it tell you?

My guess is that the check valve in the bypass has failed. Summit Racing offers a rebuild kit for this for about $25. It's really easy to install. Your symptoms are exactly that of a failed bypass.
Mark glad to here from ya. The snap on scan tool ran the ecp in voltage. My understanding with a voltage higher numbers means lower pressure. If I’m correct?!? i believe I got the line pressure information from both Sensors or one of these pins.. The scanner read Either 11 EPCP/12 ECP. the Scanner read them in live data feed. In voltage and scanner told me how to convert it into degree.. also did the transmission oil temp TFT.. the same way. Correct me if I’m wrong!?!?. This is all learning as I go.. truck, trans, and scanner 😅..

I agree on bypass valve.. tested it not to long ago leaked don’t hold back at all. Would the by pass valve cause the shift issues as well. Definitely understand why it gets hot... Thank you for guiding me in that direction From other post your in.
So the bypass valve.. delete, rebuild, buy new.. I was thinking of adding Smaller cooler like a power steering pump cooler with a Electric fan to fit. between the exit and Entering an the bypass valve but still use the original setup of fords design to makes sure al parts are oiled all times. Truck runs strait to Air cooler. It is not in the coolant radiator. the cooler is stock. My plan is to put it back on in the front all radiators?!?.
 

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Mark glad to here from ya. The snap on scan tool ran the ecp in voltage. My understanding with a voltage higher numbers means lower pressure. If I’m correct?!? i believe I got the line pressure information from both Sensors or one of these pins.. The scanner read Either 11 EPCP/12 ECP. the Scanner read them in live data feed. In voltage and scanner told me how to convert it into degree.. also did the transmission oil temp TFT.. the same way. Correct me if I’m wrong!?!?. This is all learning as I go.. truck, trans, and scanner 😅..

I agree on bypass valve.. tested it not to long ago leaked don’t hold back at all. Would the by pass valve cause the shift issues as well. Definitely understand why it gets hot... Thank you for guiding me in that direction From other post your in.
So the bypass valve.. delete, rebuild, buy new.. I was thinking of adding Smaller cooler like a power steering pump cooler with a Electric fan to fit. between the exit and Entering an the bypass valve but still use the original setup of fords design to makes sure al parts are oiled all times. Truck runs strait to Air cooler. It is not in the coolant radiator. the cooler is stock. My plan is to put it back on in the front all radiators?!?.
 

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Mark glad to here from ya. The snap on scan tool ran the ecp in voltage. My understanding with a voltage higher numbers means lower pressure. If I’m correct?!? i believe I got the line pressure information from both Sensors or one of these pins..
Higher voltage does mean lower commanded pressure. Is it commanding pressure lower than it should be? You did NOT get line pressure information from ANY sensors because there are NO line pressure sensors. There is nothing that tells the PCM what the line pressure really is. All that is knows is what voltage is commanded to the ECP. And that doesn't tell you what line pressure is.

I was thinking of adding Smaller cooler like a power steering pump cooler with a Electric fan to fit.
Don't do that. It will cause too much restriction and you will have less cooling than you have now.

Replace the cooler you have with a cooler from a 2003-2007 6.0L truck. That will greatly improve the cooling.
 

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Higher voltage does mean lower commanded pressure. Is it commanding pressure lower than it should be? You did NOT get line pressure information from ANY sensors because there are NO line pressure sensors. There is nothing that tells the PCM what the line pressure really is. All that is knows is what voltage is commanded to the ECP. And that doesn't tell you what line pressure is.


Don't do that. It will cause too much restriction and you will have less cooling than you have now.

Replace the cooler you have with a cooler from a 2003-2007 6.0L truck. That will greatly improve the cooling.
I have a cooler from my 6.0 shuttle bus. It looks smaller than then others 6.0 coolers.. I’ll Send a picture Of it
With the pressure being commanded low. My thought on why is the (CAP) cold setons for the truck to warm. It seems to be turn on when it’s warm. Why I think this because I’m lowered on power and exhaust brake kicks on. also high idle will come up at stops.my understanding Lower line pressure is commanded for the cold to help warm the trans. Then once warm back to to Normal pressure.. Truck seem to come in and out of of cold settings or maybe it’s was limp mode. Not sure. Limp mode should have a code set with it though..
illl get these few things handle and test again with scanner..start fresh again. Thanks 🙏
 

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Higher voltage does mean lower commanded pressure. Is it commanding pressure lower than it should be? You did NOT get line pressure information from ANY sensors because there are NO line pressure sensors. There is nothing that tells the PCM what the line pressure really is. All that is knows is what voltage is commanded to the ECP. And that doesn't tell you what line pressure is.


Don't do that. It will cause too much restriction and you will have less cooling than you have now.

Replace the cooler you have with a cooler from a 2003-2007 6.0L truck. That will greatly improve the cooling.
I have a cooler from my 6.0 shuttle bus. It looks smaller than then others 6.0 coolers.. I’ll Send a picture Of it
With the pressure being commanded low. My thought on why is the (CAP) cold setons for the truck to warm. It seems to be turn on when it’s warm. Why I think this because I’m lowered on power and exhaust brake kicks on. also high idle will come up at stops.my understanding Lower line pressure is commanded for the cold to help warm the trans. Then once warm back to to Normal pressure.. Truck seem to come in and out of of cold settings or maybe it’s was limp mode. Not sure. Limp mode should have a code set with it though..
illl get these few things handle and test again with scanner..start fresh again. Thanks 🙏
 

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Left side is from the 2006 6.0 Powerstroke e350 shuttle bus.. 7.3 right side early 1999 f450 PowerStroke.. seems a bit smaller I have seen others much larger guess that’s for the truck? Should I use that one or no both are cleaned and flow seem great..
 

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Left side is from the 2006 6.0 Powerstroke e350 shuttle bus.. 7.3 right side early 1999 f450 PowerStroke.. seems a bit smaller I have seen others much larger guess that’s for the truck? Should I use that one or no both are cleaned and flow seem great..
 

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I should have said 6.0L F-Series. Don't use an E-Series cooler, they are tiny.

Low pressure is not commanded cold. That would cause the trans to slip and be destroyed in a mile or two. Pressure is commanded based on engine torque. If the engine is making less torque when cold, such as when the exhaust is restricted, will cause less line pressure. That's how it works and is not a problem.
 

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I should have said 6.0L F-Series. Don't use an E-Series cooler, they are tiny.

Low pressure is not commanded cold. That would cause the trans to slip and be destroyed in a mile or two. Pressure is commanded based on engine torque. If the engine is making less torque when cold, such as when the exhaust is restricted, will cause less line pressure. That's how it works and is not a problem.
Bypass cooler I had to order so I ordered a new one. Mean while I did a delete. I cut the line and welded each end of the cut tube shut. Only did this to keep on moving forward. The trans cooler is now getting flow.. Trans only is running hot but not at all as bad still to hit though and slipping in 4th and hard **** into second. it’s throwing a code now so I’ll check that today with scanner. I’ll Triple check the harness wires. I’ll change fluid yet again. It honestly could be bad fluid adding to the symptoms . . I have a bad diesel fuel leak still. This could be the torque issue U said With engine. Once I’m done I’ll update again.. if I keep it In drive (overdrive off) it will not get to hot.. I used original 7.3 cooler FYI
 

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Bypass cooler I had to order so I ordered a new one. Mean while I did a delete. I cut the line and welded each end of the cut tube shut. Only did this to keep on moving forward. The trans cooler is now getting flow.. Trans only is running hot but not at all as bad still to hit though and slipping in 4th and hard **** into second. it’s throwing a code now so I’ll check that today with scanner. I’ll Triple check the harness wires. I’ll change fluid yet again. It honestly could be bad fluid adding to the symptoms . . I have a bad diesel fuel leak still. This could be the torque issue U said With engine. Once I’m done I’ll update again.. if I keep it In drive (overdrive off) it will not get to hot.. I used original 7.3 cooler FYI
 

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Fixed the fuel leak. No codes come up on engine or powertrain.. engine runs better than ever now. Mostly only know this from idle cuz shifting is another story . Temp sensors oil and coolant were changed New ICP and MAP. Noticed wires got warm on shifter Overdrive wires.. so I pulled it all out. New ford shifter lever Seemed like some times it didn’t work so why not.

the trans has gotten a new transmission control harness put on internal solenoid pack. Solenoid pack was also installed. Then knew inputs turbine shaft sensor ( made for the PTO setup.. also has new output shaft sensor. The diff.. vehicle speed sensor was Also changed..
Has a new DTS.. I believe the voltage was low and still is to it. Brake light switch was changed. Trans feels like im holding the brake and pushing the throttle. best way to explain symtoms trans if having. Third brake light was installed and put on never has had one factorY cover was on the 3rd brake light and plug was inside with factory plug cover. I put a light on it because threads say to plus nothing els has worked.
I have went top to bottom checking all wires. I did make a couple Mistake on wires to solenoid pack ( weird no codes though either way no codes).

The problems
one thing I do notice my shifter don’t need a brake peddle to come out of park.
voltage I believe is low on range sensor with only and new part installed.
line pressure command is low on transmission.
truck will sometimes ( mostly first start of the day). easly picks up speed and float down the road. Most ( basically always ) of the time truck struggles seems like Im pulling a rock..
When truck floats down the road trans all is working normal. When truck is faulting with no lights saying it’s faulting on dash or shifter lever it’s low on power hard to keep speed no 4th gear. Hard shifts
Have to let off Acceleration peddle to shift gears. .

Where do i go from here.? Do I just pull the trans buy a HD rebuild kit also a torque converter, valve body and solenoid pack and start over?
if not what do I test next or what test u need the answer to tell me the next move..


Thanks for any and all help. I’m open ears fully
 

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The next step is to find and fix the problem with the brakes. They are dragging.
 

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The next step is to find and fix the problem with the brakes. They are dragging.
My brakes are lot actually dragging on the truck but the signal to them seem to be. Brakes were the first thing I started with. I’m at a loss on what els to look into on the brake side of all this: I have checked and replaced switch my peddle fully comes up and disengages the brake on off switch.. is there more I’m missing or something I could test to help u rule out somthing that’s messing with the brake system?
 

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I’m getting a P1728...

Truck is in and out of power a bit erratic like converter on and off... but not following as commanded from PCM.. With a converter on off switch added the converter lock is weak or no change when applied.. Trans solenoid control plug need replaced. Its on but I can’t say I trust it. Transtemp will go off the charts if I let it,

Here goes. I start the truck take off no flashing o/d. With O/D light off Truck will shift fine all the way to 3rd. Trans shift into O/D. Then out of no ware. Not always right away.. it will feel weak on power and shift It down shift to 3rd.. I push o/d off no change in rpm. Push O/D again No changed. Gear shows in third on scan tool. Some times if I let off throttle it will up shift but come Right back to 3rd with in 2-3 seconds.

Now after a a few miles of driving the O/D light starts flashing. Power comes back ( feels light the anchors have been pulled ... Trans shift all threw the gears Even into O/D.. I can push the o/d bottom and watch rpms change. While in O/D the trans will slip by time I get to higher speeds. O/d off light still flashing no slipping..

Temp Of trans only goes up when the power of truck weakens. I’m force to throttle harder to Try and maintain speed. If I go 40 mph trans cools To Normal Temps. Truck operated normal. Also at this speed I shift into over drive converter locks. O\d Can be flashing or not under 40 it’s normal.

🤯🤯. Restart truck and the process repeats.
 

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The range sensor doesn't work by varying voltage. It works by making and breaking different circuits depending on where the shift handle is located.

Why are you asking this? What makes you want to look at the range sensor? Nothing in the data you showed even shows the range sensor, and none of your symptoms point towards the range sensor. I'm puzzled.
 
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