Torque converter clutch?
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Postmaster
Joined: Oct 2006
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From: Davis & Newcastle, CA
Torque converter clutch?
So after a long, hot, trafficky trip back to Davis today I checked the temp of my torque converter with an IR temp gun, 170-180*, sounds about right.... right?
Anywho, parked it and did some work for a couple hours, got back in and started driving home. I noticed that at low speeds if I suddenly let completely off the gas, the engine would silence for a split second and sound like its gonna die, then spring back up to idling speed. It happened several times but VERY quickly, almost undetectable. Is this a problem with my TC clutch not disengaging quickly enough?
Anywho, parked it and did some work for a couple hours, got back in and started driving home. I noticed that at low speeds if I suddenly let completely off the gas, the engine would silence for a split second and sound like its gonna die, then spring back up to idling speed. It happened several times but VERY quickly, almost undetectable. Is this a problem with my TC clutch not disengaging quickly enough?
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Joined: Nov 2006
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From: Quad Cities, IA
How low of speeds are we talking about here? If it's low enough to "idle" when you let off the gas, I sincerely doubt your TCC is even engaged at this point. They usually don't engage until you reach a "cruising speed" (they kind of act like an extra gear in your transmission, but not), and if it engages sooner than that, you've probably got a problem.
I would honestly think it to be more of an engine issue than a transmission issue at this point. If you're travelling fast enough for the TCC to engage, when you let off the fuel, it shouldn't drop down to idle in an automatic.
I would honestly think it to be more of an engine issue than a transmission issue at this point. If you're travelling fast enough for the TCC to engage, when you let off the fuel, it shouldn't drop down to idle in an automatic.
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From: Davis & Newcastle, CA
Ahhh, well this is at low speed but your comment at the end makes me wonder:
Lately I have noticed that my RPMs are not falling back down to an idle when I let off the gas.... But it also doesn't exactly feel like I'm riding a gear down like a manual transmission (TCC locked up). Is there a sure fire way to diagnose the TCC?
Originally Posted by Wild Karrde
If you're travelling fast enough for the TCC to engage, when you let off the fuel, it shouldn't drop down to idle in an automatic.
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From: Quad Cities, IA
When I diagnosed a TCC issue in my IROC, I wired a toggle switch (one side to a hot wire, the other in place of the wire that goes into the plug on the transmission) so I could manually control TCC lockup. Some people will do this on their "street racers" to bypass TCC lockup entirely, or to be able to use it only when they want to.
After I did this, I found out that I did have a bad TCC (or at least the controller for it). When I left it engaged all the time, it did the exact same thing as it did before I wired the switch, but when I disengaged it at lower speeds, the car drove like it was supposed to.
I can't honestly say this would be a good permanent fix, but it DOES work to test it. Find in a shop manual or online which wire on your transmission is the TCC lockup control and replace it with a toggle (or you could actually just unplug that one wire and test it that way if you don't want to run a switch). If when disabled, your truck drives like normal at low speeds, it's probably the TCC. If not, it's most likely something else.
After I did this, I found out that I did have a bad TCC (or at least the controller for it). When I left it engaged all the time, it did the exact same thing as it did before I wired the switch, but when I disengaged it at lower speeds, the car drove like it was supposed to.
I can't honestly say this would be a good permanent fix, but it DOES work to test it. Find in a shop manual or online which wire on your transmission is the TCC lockup control and replace it with a toggle (or you could actually just unplug that one wire and test it that way if you don't want to run a switch). If when disabled, your truck drives like normal at low speeds, it's probably the TCC. If not, it's most likely something else.
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From: Davis & Newcastle, CA
Yeah I kinda figured a lockup switch was in order... I attempted it a few weeks ago but tapped into the wrong wire because the wire colors were so faded. No damage done to the truck. I suppose I'll have another crack at it for testing purposes. Thanks.
Last edited by Skandocious; Aug 20, 2007 at 12:34 AM.
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Joined: Oct 2006
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From: Poquoson Va.
I have a 93 F-150 351W E4Od and put a toggle switch to control Lockup TC. It works well. Its the Pink and white wire. Subford can tell you more. I need to install lower gears for my 35s but if I cut off lockup converter, it feels faster. If im not playing I leave it alone for gas milage.
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saltwaterman
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Jan 4, 2006 07:45 PM
