No TC Lockup Questions

[RandomNerd2000]

So, basically, to make a long story short, and sum up a bunch of stuff I've posted on, soon, I'm going to be doing my 5.0 build, fixing my rolled V8, and as such, I'm going to have a ton of parts around for a SOHC (like my 01), so I'd like to take some of a look at the weird trans issue I was experiencing a while back, since it seemingly has stayed stagnant, and was believed to be a TC lockup issue, was abnormally high RPMs at road speed, semi-low MPG. Mainly, I want some of my options, and likely solutions explained to me, since I'm new at the trans end of things, and have a poor idea of what to do with this, it's an 01 4.0 SOHC 4WD

 

[drdoom]

First clarify is it the V8 transmission or the SOHC?

 

[RandomNerd2000]

SOHC, I edited the post to reflect that.

 

[drdoom]

Nerd is the TCIL flashing? If so what codes are stored? It has been a while back, but I do have some experience with this. In short my torque converter clutch system failed. This resulted in a serious vehicle fire, to read more just Google "Ford Explorer trial by fire" it should be at the top of the results. YMMV

 

[RandomNerd2000]

It's not, and last I checked, the bulb was working, which is what's strange, because it shifts just fine, just has high RPMs at that speed, and I've been told that my 4:10 gearing is part of it, but not *all* of it.

 

[drdoom]

OK. You can pull live data and see if the TCC solenoid is coming on, and also you can confirm on the screen which gear you are in.

 

[RandomNerd2000]

Well alright, I'll do that and get back to this asap. What are my options if it is/isnt? It's a learning curve with this mostly.

 

[Dono]

If tc lockup is being commanded by the pcm, and isn't happening, you should get that pesky red flashing od light on your dash.

If you have something that you can see the tc lockup being commanded via the odb2 port, you would see a corresponding rpm drop of a few hundred rpm on the tach.

Has your pcm been programmed to compensate for the gears?
I don't think that would be your issue though. If anything, the pcm would think you are driving faster than you are with the engine seeing lower load and want to lock the tc clutch even faster (I think).

If the tc clutch is not locking up when commanded, its got to be wiring, trans fluid pressure (maybe?), or a worn out tc.

Iv'e struggled with tc lockup myself in the past, but it was always due to pcm tuning issues

 

[imp]

TCC is the most over used, and under estimated part of the system. Your tach may be used to confirm TCC lockup, it will not increase rpms under very light throttle if the TCC is engaged. If the tach jumps up, at 50 mph, cruising level, when gas pedal slightly increased, TCC is not engaged. imp

 

[RandomNerd2000]

The truck shipped, out the door, with 4:10 gears, so it should be programmed for them in theory. Haven't driven it much in this cold weather since the roads are frozen, gonna take it out later today though

 

[Turdle]

Disconnect the battery for a few minutes to reset the PCM, then go for a drive, see if the TC locks up.

 

[RandomNerd2000]

Okay, so, I've got an idea there's a problem, basically, took off from a dead stop, counted all the shifts, there was 5, and at 55, it went into lockup, so, slipping TC? If that's the case, I'll probably leave it until I eventually swap that 4.0 out, since the timing chain guides are gonna give sooner or later

 

[imp]

Okay, so, I've got an idea there's a problem, basically, took off from a dead stop, counted all the shifts, there was 5, and at 55, it went into lockup, so, slipping TC? If that's the case, I'll probably leave it until I eventually swap that 4.0 out, since the timing chain guides are gonna give sooner or later

@RandomNerd2000

Right here is something I've never seen addressed! If a TCC is engaged, but for some reason is able to slip any significant amount, will that generate more heat than the normal heat built-up by the Torque Converter? Seems like it should. If you see 5 "dips" of the tachometer getting up to steady cruise speed, that last one shows the lock-up of the TCC. If slight additional throttle "blips" the tach upwards, the TCC is either slipping, or not engaged. If the TCC does not engage when the PCM commands it, the engine speed will not match the transmission input shaft speed, and a code or codes will be thrown, along with the "O/D OFF" light flashing. imp

 

[RandomNerd2000]

Hmm, well it's not throwing a flashing "O/D OFF" light, but works fine if you mash the button, clear downshift when you do that, there any chance it's been re-geared in the rear end to have something other than 4:10s? If so, what are the signs really of that?

 

[imp]

Hmm, well it's not throwing a flashing "O/D OFF" light, but works fine if you mash the button, clear downshift when you do that, there any chance it's been re-geared in the rear end to have something other than 4:10s? If so, what are the signs really of that?

@RandomNerd2000
You ask the best questions! Another imponderable, for me! If axle ratio is changed, and the PCM is factory-programmed to be expecting a certain comparable ratio of shaft speeds between transmission output shaft (driveshaft speed) and rear wheel speed sensor output, things could possibly go haywire, IMO. Still, IO would expect a code to be generated. Sorry I can't help. imp

 

[RandomNerd2000]

I'm giving thought to swapping in the cluster from my 99, for testing since it's 40K miles lower, since the 4WD lights don't work on this cluster half the time, and part of the blacklighting is the same way, and see if anything changes, I know the cluster hasn't ever been out, the title showed that when I bought it, and a 99 cluster should work in an 01.

 

[drdoom]

Hmm, well it's not throwing a flashing "O/D OFF" light, but works fine if you mash the button, clear downshift when you do that, there any chance it's been re-geared in the rear end to have something other than 4:10s? If so, what are the signs really of that?

So the TCIL does illuminate when you do so? Sorry just tryin' to keep up here

 

[RandomNerd2000]

Nope, it's not, which is something I find odd, considering when I mash the button, it clearly changes.