I kind of introduced myself in this post and started asking questions about this new to me 2000 F-350 with 7.3L. https://www.ford-trucks.com/forums/1...questions.html

I wanted to start a new thread specifically about problems with what I believe to be the torque converter lockup. The transmission was rebuilt about 30K miles ago by the previous owner and I have the receipt showing work that was done. The receipt stated that a "E4OD Heavy Duty Billet Torque Converter" was installed.

I know that some of my issues come from 35 inch tires, and I believe the truck has not been re-geared. I will try to check that this weekend. What I'm experiencing is a 200-300 rpm hunting that happens at around 60-65 mph then eventually settles in the lower RPM range. I know it isn't the 3rd to 4th gear shifting, because if I turn off O/D, I get a larger rpm jump. So I'm assuming this is the TC locking up and finally settling in the locked position.

So here's the other observation I have made. When cruising at about 70 mph on the freeway, the RPM will fluctuate between about 1900 going down hill to almost 2500 on steep grades. There are no shifts, just gradual change in rpm as the load increases or decreases. If the TC is truly locked, this shouldn't happen correct?

This site seemed to indicate that bad fuel injectors can also cause "The RPM needle to start to Dance" https://www.firestonecompleteautocar...ctor-symptoms/

This doesn't make sense to me. But, one of my issues from my other post was poor fuel mileage.

Engine never misfires and runs good. Only had one issue starting on a cooler (50 degree) morning in the mountains. I live in Yuma, so this time of year it never drops below 80. It started on the third time after waiting for the "wait to start" light go off each time. Maybe week glow plugs?

I will be pulling an 8,000-10,000 lb trailer and don't want to burn up my transmission if my TC isn't locking up. I know for many years auto transmission never had locking TCs, but I don't know if these newer systems were designed for that. I have purchased a 6.0 transmission cooler and ordered EGT, Boost and Trans temp gauges, that I plan to install before towing. I also plan to check my EBPS and check for boost leaks, but don't know what else I should do before hitting the road.

Is there a scan tool that can tell me if there is slip in the TC? I'd rather replace a faulty TC than have a transmission replaced while on vacation.

Thanks for the help.

Jonny

 

You can use Forscan to read torque converter slip. Having slip in the torque converter when it should be locked could be a bad converter, but it also could be a bad seal on the input shaft or a bad torque converter clutch control valve. If the torque converter clutch solenoid is bad there should be a code for that. Have you checked for codes?

 

I'll look into getting FORSCAN. Is there a specific scanner you recommend? I'd prefer something for Android, but it sounds like to get the full capability I need to get a windows version. Is that correct? Will the Android version tell me if there is slip in the Torque Converter?

I ran a scan with my Superchips 1705 and it brought up a P0603 code. It looks like this may be related to changing tunes with the 1705. FYI, I have changed from Performance, to stock and most recently to economy mode to see what mileage is like.

No other codes.

 

I haven't tried Forscan with an Android. I have only used it with a Windows laptop.

 

Just took a 1,600 mile round trip pulling at 10k lb trailer from Southern AZ to central UT. The transmission got HOT on the hills.

Flat or down hill transmission stayed in the 180-195 range. As soon as I had any incline, I would notice slipping in the torque converter and trans temp would start to climb. At 210 I would turn off the A/C. At 230, I would gear down to 2nd (I almost always ran with OD off except long down hill stretches) and cruise at 45-50 mph, at 250 I was looking for the nearest place to pull over and cool down. On a long steady incline this process would take 10-15 minutes to go from 195-250.

Under load (uphill or OD on flat) I could see the RPM rise with pretty constant speed. I also never used cruise control, because I could let off on the accelerator to try to keep RPM in check if I noticed slipping.

To put it simply, this trip was extremely hot and stressful. Maybe I was being over cautious and paranoid, but my main objective was to get my family home without any failures, and I'm happy to say I was successful in that. Even though my kids were complaining about the heat and how everybody was passing us.

Some observations: When trans temps rose above 210, my A/C wouldn't blow as cold. This is one of the reasons I chose to turn off the A/C at this point. I didn't want the condenser and the cooler competing for cooling. This also makes me think that the cooler is working, though I will do the bypass test I've read about when I get a chance.

I noticed a high pitched intermittent buzz/squeal when under heavy load. It's hard to pinpoint exactly where it was coming from, but it sounded like it was on the driver's side dash area. There were no check engine lights or flashing OD off light. It wasn't the A/C compressor, it would happen even if A/C was off.

Once the TC would start to slip, it seemed to be a loosing battle to get it to grip again. When cold and running flat it seemed to lock good, until it heated up and it didn't. I tried tapping the breaks a couple times to see the RPM change when TC unlocked. When cold, it would jump 300-400 rpm. Once on a long hill (hot) I tapped it and there was almost no change in RPM.

So, Was I being over cautious and paranoid? I drove to work today (25 miles highway relatively flat) and the temp never got over 150. I don't have another trip planned yet, but hope to do something else this summer. I don't want another trip like the last. I need to get a FORSCAN reader, but I'm not sure what it will tell me that I don't already know. Will this tell me if pump pressures are low causing a weak lock in the TC?

I already installed the 6.0 cooler before this trip, so I don't think I need more cooling. I checked for codes after the trip using my Superchip 1705 and there were no transmission codes. Would the FORSCAN tell me if there was a slip condition or overheat condition that the 1705 wouldn't tell me, or do I have to have it plugged in while under load to monitor conditions?

Is there anything other than FORSCAN I can do to troubleshoot? What FORSCAN readers do you recommend? There are so many options and I have read to beware knockoffs. I don't mind spending the money for the right tool, but don't want to spend $300 when the $20 tool will work. I would also prefer a Bluetooth/Android reader if it will give me the detail that I need, but I've also read that the Windows/USB readers have more options/tools.

Anyone have experience with this one?
Or should I go with this one?

Sorry for the long post, but thought in this case more information might help others.

Thanks,

Jonny

 

I was running stock tune the entire trip.

 

Tapping the brakes to see if the converter will unlock only works if you are very light on the go pedal. If you are more than about 10% into the pedal tapping the brakes will not cause the converter to unlock.

If you were light enough on the pedal when hot, this would indicate that the converter isn't locking.

If there is a problem that is causing the converter to be unlocked it WILL set a code. You need Forscan to read this code. I don't have a lot of confidence that what you have can read transmission codes.

It may also not be locking due to the schedule for lockup not calling for lockup at the speed that you're running.

Forscan doesn't know what actual pressures are. It can read what the PCM wants the pressure to be, but there are no sensors to tell it what the actual pressure is. You need a pressure gauge to read that. But first, get Forscan and read the codes.

You could have a failed bypass. Summit Racing has a rebuild kit for the bypass that is really easy to install. And it only costs about $25.

I have no idea what the 1705 can and cannot do. Forscan can do this. It would be best to read data when you think it's having a problem. According to the numbers you shared you haven't overheated the transmission, though you did come close.

Yes, there are some very expensive scan tools that can do what Forscan can do. I bought my OBDII dongle for about $30 from Amazon, and the Forscan download is free. So you can spend $30 for Forscan or a couple grand for a scan tool that can do the same thing.

I tried some Bluetooth dongles and couldn't make them work. I have a USB dongle and use a laptop. A laptop can do a lot more than Android for Forscan.

 

Thanks Mark. As always your answers are very helpful and appreciated.

I'll go with the USB FORSCAN reader and go ahead and get the bypass rebuild kit.

I'm sure the time I tried the brake tap in the hot condition, I was into the throttle more than 10% so it makes sense that it wouldn't have unlocked.

I'm pretty sure that the TC was locking, I could feel the shift in RPMs. I never felt it unlock, the RPM would just slowly drift from the speed. My big question is why is it slipping. I'm thinking the simple answer is a bad TC, but don't want to discount the possibility of low pump pressure, a bad solenoid or something else I haven't thought of. Hopefully the scan tool will identify codes that will help diagnose. I'll post up when I get a chance to test it.

Thank again.

 

It maybe cheaper to just order a new Ford bypass kit instead of rebuilding it.





Also it’s very common for the torque converter to fail in these trucks, you can do a simple check and pull the inspection plate off and see if the torque converter is starting to go dark blue/purple.

 

I found a rebuild kit for $26 after shipping and already ordered it. Thanks for the search though, I might have gone for that option if I'd seen it earlier.

So if the TC is failing it starts to discolor the case from the heat? I would think if it is getting hot enough to discolor the metal of the case, the internals would be long gone. I'll take a look this weekend.

Thanks.

 

If the torque converter is slipping, the torque converter front face will discolor, not the trans case. If you remove the cover on the front of the bellhousing you can see the front of the torque converter. If it is blued the torque converter is all done.

 

It doesn't look discolored to me

 

No, it is not discolored. I don't think there is anything wrong with this converter.

 

I finally got a chance to take the trailer out last week.

I did the cooler bypass rebuild about a month ago, but never saw any difference in temperatures (it never overheated except when towing).

The bypass rebuild seems to have solved all my overheating issues. Even on the long up-hills, the temperature never got over 190. I didn't notice any slipping in the torque converter either. I don't know if the slipping I was seeing before was a cause of the overheating or a result, but either way, they both seem to be fixed.

Thanks for all the help.

Jonny