Ballooning torque converter?

[85lebaront2]

The engine and transmission are both 1995, from the donor truck. They are also both freshly rebuilt, and I have no reason to believe either is malfunctioning in any way. However, I did the rebuild on both so anything's possible. The engine is strong enough to squeal the tires from a stop.

The transmission had a shift kit put in during the rebuild. The solenoid pack was also replaced with a new one.

I will have to check with Baumann about the EPC protection diodes. But they advertise their product as compatible with all years of E4OD, so I would think they are in there. What does EPC stand for in this case?

I should get the filter device today and will give it a try and report back. Thanks!

EPC is normally used for Electronic Pressure Control, but I believe the usage here is referencing all the solenoids (shift 1, shift 2, EPC, Coast Clutch and TCC).

There is a stall speed test for torque converter function, but as I believe I mentioned it is partially dependent on engine condition. An extremely low stall speed if the rest of the engine's performance is good, is usually indicative of a stator issue inside the converter. If the one-way clutch is slipping you won't have a torque converter, just a fancy fluid coupling. Stall speed specification is 22 - 2800 RPM, if you can't get near those figures I would definitely suspect the stator clutch is bad.

One item. if it is a factory, or good remanufactured converter, there is a drain plug (Allen screw) on the OD of the converter. If so and you take it loose and get metal in the fluid coming out, or if you can possibly hear a squealing noise during initial acceleration, either would be indicative of a stator clutch problem. There is a test for them, but it can only be done with the converter out on the bench.

[Pete Whitstone]

EPC is normally used for Electronic Pressure Control, but I believe the usage here is referencing all the solenoids (shift 1, shift 2, EPC, Coast Clutch and TCC).

There is a stall speed test for torque converter function, but as I believe I mentioned it is partially dependent on engine condition. An extremely low stall speed if the rest of the engine's performance is good, is usually indicative of a stator issue inside the converter. If the one-way clutch is slipping you won't have a torque converter, just a fancy fluid coupling. Stall speed specification is 22 - 2800 RPM, if you can't get near those figures I would definitely suspect the stator clutch is bad.

One item. if it is a factory, or good remanufactured converter, there is a drain plug (Allen screw) on the OD of the converter. If so and you take it loose and get metal in the fluid coming out, or if you can possibly hear a squealing noise during initial acceleration, either would be indicative of a stator clutch problem. There is a test for them, but it can only be done with the converter out on the bench.

Thanks Bill, a lot of good information there. On this:

>>>>Stall speed specification is 22 - 2800 RPM, if you can't get near those figures I would definitely suspect the stator clutch is bad.

When you say "can't get near", would a bad stator clutch have the observed RPM under or over those numbers? In other words would the engine RPM rise to say 1400 and stop, or would it shoot way past the 2800 RPM mark? Or could it be either?

[85lebaront2]

Thanks Bill, a lot of good information there. On this:

>>>>Stall speed specification is 22 - 2800 RPM, if you can't get near those figures I would definitely suspect the stator clutch is bad.

When you say "can't get near", would a bad stator clutch have the observed RPM under or over those numbers? In other words would the engine RPM rise to say 1400 and stop, or would it shoot way past the 2800 RPM mark? Or could it be either?

It would be well under the specified values, over is usually due to major amounts of slippage internally.

[mat in tn]

It would be well under the specified values, over is usually due to major amounts of slippage internally.

just curious. did this happen suddenly, or did it get to this performance level slowly, progressively?

[Pete Whitstone]

just curious. did this happen suddenly, or did it get to this performance level slowly, progressively?

I think it's always been there. When the old, weak engine was in the truck I dismissed it as just that. This was with an old 351w with the newly rebuilt transmission and the original TC. Then I rebuilt the engine and babied it for 500 miles, and now that I'm out of the break-in period, I can explore the performance a little more. Mind you, I only put between 1 and 3k miles on it in a year, so not a huge amount of data to go on.

But with the old, weak engine (and new trans and the re-used TC), I think this problem was present but disguised. Which unfortunately would mean cleaning up the TPS signals probably won't do anything. The filter thingie arrived last night, but it will be tomorrow night before I can install it and test it.

[mat in tn]

just curious. did this happen suddenly, or did it get to this performance level slowly, progressively?

I think it's always been there. When the old, weak engine was in the truck I dismissed it as just that. This was with an old 351w with the newly rebuilt transmission and the original TC. Then I rebuilt the engine and babied it for 500 miles, and now that I'm out of the break-in period, I can explore the performance a little more. Mind you, I only put between 1 and 3k miles on it in a year, so not a huge amount of data to go on.

But with the old, weak engine (and new trans and the re-used TC), I think this problem was present but disguised. Which unfortunately would mean cleaning up the TPS signals probably won't do anything. The filter thingie arrived last night, but it will be tomorrow night before I can install it and test it.

I'm very intrigued as how all this is going to work out. I generally build analog and avoid any type of ecu on these antiques as I just prefer it that way. I have ecu vehicles and work on many, but I just like the old stuff as a reprieve to simplicity. the last pro 4 I had anything to do with was an abysmal failure. spent more time dealing with edelbrocks tech then wrenching. enough so that they wanted the assembly shipped back to them. they sent a second and it was no better, enough so that they wanted the second sent back. We then installed a four-barrel performer and their avs 2 carb and was very impressed. tire smokin vette! on the efi setup everything worked just not well. every sensor read, the ecu monitored and communicated and the handheld responded well, and nothing behaved in a way to lead us to installation.

as for the trans controller I have not dealt with Bauman controls. I have only used hgm's compu-pro. it works awesome, but I am using their tps on a Holley 3310.

[Pete Whitstone]

I'm very intrigued as how all this is going to work out. I generally build analog and avoid any type of ecu on these antiques as I just prefer it that way. I have ecu vehicles and work on many, but I just like the old stuff as a reprieve to simplicity. the last pro 4 I had anything to do with was an abysmal failure. spent more time dealing with edelbrocks tech then wrenching. enough so that they wanted the assembly shipped back to them. they sent a second and it was no better, enough so that they wanted the second sent back. We then installed a four-barrel performer and their avs 2 carb and was very impressed. tire smokin vette! on the efi setup everything worked just not well. every sensor read, the ecu monitored and communicated and the handheld responded well, and nothing behaved in a way to lead us to installation.

as for the trans controller I have not dealt with Bauman controls. I have only used hgm's compu-pro. it works awesome, but I am using their tps on a Holley 3310.

OK was finally able to throw some time at this. Last night I installed the TPS filter/doubler and took it for a test drive. No difference to the problem I am chasing.

Next I tried a brake stall test. I wasn't really able to fully complete this, as engine torque overcame the brakes at about 1900rpm. I am reading that as a good sign in HP/torque production, and that the engine and controlling software are basically healthy.

Next I tried to put it in first and see how it reacted. The reasoning was that if it was a TC problem, it should not matter if the gear was selected automatically or manually. The truck did not misbehave in this mode, it pulled steadily and strongly up to the point where I shifted, maybe 4500rpm. So I took this as a sign that the TC was healthy.

At this point, since the truck worked fine when shifted manually but did not when shifting automatically, I had to believe something was going on with the trans controller or software. Out of curiosity I generated up a new controller map and loaded into the Quick 2. Took it for a test drive, and it was a huge improvement.

I say improvement because it held the gear and ran the engine up far further than expected, it didn't "stall out" RPM-wise in the 2000s.

I can't say the problem is completely cured, however. When I floor it and go WOT, there is still some hunting between gears when it should be holding the gear. So I think there is still something going on with the TPS signal. I need to get some data logging on the trans controller and see what the TPS signal is doing. I think it will reveal an unstable signal.

I think the reason for this is, the instructions for the trans controller are adamant that it be grounded as close to the engine controllers ground as possible. This is so they see the same "ground potential", which I interpret as "eliminate the possible resistance between the battery negative post and the controller units". Each controller unit is grounded back to the battery negative post on its own wire. So there is about 16-18 feet of ground wire separating the two computers, although they are physically less than 2 feet apart. I might try running a jumper wire between the two computers grounds, effectively making a ground triangle. I think that would negate any ground potential difference between them, but I'm not an EE so if someone thinks this is a bad idea or is not going to work, let's hear it.

I'll post up the results of the transmission TPS data logging when I have them. Right now I'm just relieved that there does not appear to be a hardware problem of any kind.

[Gary Lewis]

OK was finally able to throw some time at this. Last night I installed the TPS filter/doubler and took it for a test drive. No difference to the problem I am chasing.

Next I tried a brake stall test. I wasn't really able to fully complete this, as engine torque overcame the brakes at about 1900rpm. I am reading that as a good sign in HP/torque production, and that the engine and controlling software are basically healthy.

Next I tried to put it in first and see how it reacted. The reasoning was that if it was a TC problem, it should not matter if the gear was selected automatically or manually. The truck did not misbehave in this mode, it pulled steadily and strongly up to the point where I shifted, maybe 4500rpm. So I took this as a sign that the TC was healthy.

At this point, since the truck worked fine when shifted manually but did not when shifting automatically, I had to believe something was going on with the trans controller or software. Out of curiosity I generated up a new controller map and loaded into the Quick 2. Took it for a test drive, and it was a huge improvement.

I say improvement because it held the gear and ran the engine up far further than expected, it didn't "stall out" RPM-wise in the 2000s.

I can't say the problem is completely cured, however. When I floor it and go WOT, there is still some hunting between gears when it should be holding the gear. So I think there is still something going on with the TPS signal. I need to get some data logging on the trans controller and see what the TPS signal is doing. I think it will reveal an unstable signal.

I think the reason for this is, the instructions for the trans controller are adamant that it be grounded as close to the engine controllers ground as possible. This is so they see the same "ground potential", which I interpret as "eliminate the possible resistance between the battery negative post and the controller units". Each controller unit is grounded back to the battery negative post on its own wire. So there is about 16-18 feet of ground wire separating the two computers, although they are physically less than 2 feet apart. I might try running a jumper wire between the two computers grounds, effectively making a ground triangle. I think that would negate any ground potential difference between them, but I'm not an EE so if someone thinks this is a bad idea or is not going to work, let's hear it.

I'll post up the results of the transmission TPS data logging when I have them. Right now I'm just relieved that there does not appear to be a hardware problem of any kind.

That's excellent news, Pete!

And you may be right that the problem is with the TPS signal and/or with the grounds. A wire 16-18 feet long can pick up a lot of static, especially if it is run in parallel with other wires carrying significant current. That creates a transformer and you'll see voltage induced into your power and ground wires.

But how well grounded is your cab? Stock there would have been a ground wire from the engine, usually a valve cover or intake manifold bolt, to the firewall near the windshield wiper. Is it there and good? If so you could try grounding the controllers to the cab - in addition to back to the battery. But don't do that if the cab ground isn't in place as then everything in the cab will use the controller's ground as its path back to the battery.

As you said, data logging may show the problem - if it is the TPS signal. But unless your controller monitors battery voltage you may not see the effects of a bad or noisy ground save for flakey signal voltages.

[Pete Whitstone]

And you may be right that the problem is with the TPS signal and/or with the grounds. A wire 16-18 feet long can pick up a lot of static, especially if it is run in parallel with other wires carrying significant current. That creates a transformer and you'll see voltage induced into your power and ground wires.

Excellent point. They do run in parallel with their respective power wire. In the case of the trans controller it also runs parallel to several other wires, the TPS wires being part of that bundle.

But how well grounded is your cab? Stock there would have been a ground wire from the engine, usually a valve cover or intake manifold bolt, to the firewall near the windshield wiper. Is it there and good? If so you could try grounding the controllers to the cab - in addition to back to the battery. But don't do that if the cab ground isn't in place as then everything in the cab will use the controller's ground as its path back to the battery.

Cab ground is in place and in good shape, it runs from the intake manifold to what I believe is the stock location, about a foot left of the brake booster, as seen when facing the firewall from the front of the truck. The engine, in turn, is grounded directly to the battery negative via a large cable that attaches at a starter mounting bolt.

But the cab ground should not be in this circuit at all, with both computers grounded all the way back to the battery.

As you said, data logging may show the problem - if it is the TPS signal. But unless your controller monitors battery voltage you may not see the effects of a bad or noisy ground save for flakey signal voltages.

In the logging, I would expect to see some swings in the TPS percentage. That's the current theory, anyways.

Thanks!

 

[Gary Lewis]

And you may be right that the problem is with the TPS signal and/or with the grounds. A wire 16-18 feet long can pick up a lot of static, especially if it is run in parallel with other wires carrying significant current. That creates a transformer and you'll see voltage induced into your power and ground wires.

Excellent point. They do run in parallel with their respective power wire. In the case of the trans controller it also runs parallel to several other wires, the TPS wires being part of that bundle.

But how well grounded is your cab? Stock there would have been a ground wire from the engine, usually a valve cover or intake manifold bolt, to the firewall near the windshield wiper. Is it there and good? If so you could try grounding the controllers to the cab - in addition to back to the battery. But don't do that if the cab ground isn't in place as then everything in the cab will use the controller's ground as its path back to the battery.

Cab ground is in place and in good shape, it runs from the intake manifold to what I believe is the stock location, about a foot left of the brake booster, as seen when facing the firewall from the front of the truck. The engine, in turn, is grounded directly to the battery negative via a large cable that attaches at a starter mounting bolt.

But the cab ground should not be in this circuit at all, with both computers grounded all the way back to the battery.

As you said, data logging may show the problem - if it is the TPS signal. But unless your controller monitors battery voltage you may not see the effects of a bad or noisy ground save for flakey signal voltages.

In the logging, I would expect to see some swings in the TPS percentage. That's the current theory, anyways.

Thanks!

Some computers ground the case, and if the case is connected to the ground wire then you could see a potential difference due to the long wire running to the battery. But the best place to start is by logging the TPS signal.