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torque converter lockup ??

Angie

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""" Head scratch... yes I fully agree spark and such, but hot or cold wouldn't affect spark. you have it or you don't ....

One other thing has entered my mind... would a torque converter act this way under any circumstances?

https://www.therangerstation.com/forums/index.php?threads/will-a-hot-alternator-kill-an-engine.197171/ """


Ok this is a continuation of that thread where I was asking about heat shutting down an alternator ....

I asked about any transmission problems that could shut down a truck and no one made any answers or suggestions ....


I want to carry on with this problem and place it now into the transmission questions threads.

The problem seemed to go away for the longest time till yesterday when it happened again.

was coming up to a red light in - OD - (overdrive) and the truck stalled out, and would not re-start ... after sitting for about 15 minutes the truck started, drove about a mile down the road, then stalled again at a red light ....

(was under the impression out of gas ... as last time and this time needle sat at 1/4 tank) so assumed gauge is out by 1/4.... got Angie to bring fuel as I also was just down the street from home. added fuel nope... still just turns over and not starting....

we hooked a chain to the truck and she towed me up the street and into the yard ... Let the truck sit for a couple hours went to see if it would to start to just move it from point A to B... yep started right away.

Today took the truck to work, stopped in and added fuel first to be sure.

ok, made it there and back with no troubles. while at work I asked the mechanic about this strange circumstances and he said yes this sounds like a torque converter lock up / sensor, and his suggestion is to drive in 3rd and not - OD - as this should prevent the OD lock up.

can anyone steer me into any electronics/sensors to check for the problem? cheers... thanks

and borrowing this from another site about this problem(s).

""There are basically three ways a torque converter lockup clutch can fail: It can stay locked up, stalling the engine when the car is braked to a stop; it can never lock up, which shows up as an increase in fuel consumption and radiator temperature; or it can slip when engaged, allowing engine speed surges at a constant vehicle speed. ""

 


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franklin2

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If the torque convertor lockup sticks you can tell. It will be just like trying to come to a stop on a manual trans truck without pushing in on the clutch. You have to press the brake hard because the engine is pulling the truck along, and then the engine starts to struggle and then you finally get it stopped when the engine chugs and turns off. This is a lot different than the engine just stalling out at a stop.

What are you working on? Is this truck all original or is the modified one with the 302 in it?
 

RonD

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+1 ^^^

You would know if torque converter was locked when slowing down, the engine RPMs would not idle and stall, RPMs would match speed of rear wheels as you slowed down(as said like manual trans/no clutch), and engine would stop when rear wheels stopped, there would be lurching as that happen, hard to miss that

Simple test is to shift in to Neutral(disconnect rear wheels from engine) as you slow down

And in D, if you let off the gas pedal at say 20MPH and engine RPMs start to drop then torque converter is not locked, if they stay the same then it is

As for fuel injected engine stalling in or out of gear, IAC Valve is where you should start, computer controls idle RPMs and is accurate +/-4 RPM so...............I would clean the IAC Valve
Also Motorcraft or Hitachi brand IAC Valves are the only ones that work with Ford computer software(PWM) system, other brands will cause issues like you describe
An old used Motorcraft IAC Valve from wrecking yard is better than new 3rd party brand

Computer opens IAC Valve all the way for start up, so stuck IAC Valve could cause hard restart
Try pushing gas pedal down a bit(let in more air) for restart to see if that helps
 
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cbxer55

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All three of my Fords, the torque converter locks up when in third, the exception being the Mustang, which locks up in fourth. I can see it on the tachs in the Lightning and Mustang, and feel it in the Ranger, when in third, the lockup feels like another shift (well almost. Trans has a shift kit). Lockup won't happen until the engine reaches normal operating temperature. It'll slip til then. All on lock up around 40 mph. And unlock when going below 40, no matter which gear. I suspect, if one was watching the tach, and going over 40 in first, second or third (fourth in a five speed), one would see lock up in all the gears.
 
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Angie

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What are you working on? Is this truck all original or is the modified one with the 302 in it?

1990 4X4 4L . as original as it can be. Reason for thinking torque converter is that I had lifted the engine out a while back to do a set of rings on it, and when I restarted the motor with a test drive, the trans stalled out the truck and shot about a liter of oil out the filler tube. died point blank at a stop sign... hasn't puked the oil out sense, so thought maybe could be a problem....

thanks for that explanation. will look into that stuff.

As for fuel injected engine stalling in or out of gear, IAC Valve is where you should start, computer controls idle RPMs and is accurate +/-4 RPM so...............I would clean the IAC Valve

Thanks Ron, will look into that valve. i have enough parts engines and trucks in the yard to be able to just walk out the door and grab another to bolt in. :)


thanks xb, will keep an eye on that also



It can stay locked up, stalling the engine when the car is braked to a stop; <<<<< if this happens, will the engine turn over with starter but not fire? or would the engine be frozen where it stalled at? this is the head scratcher as it sits then will re-fire.

cheers
 

franklin2

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The lock-up feature comes from the pressure from the oil pump inside the tranny. When the engine stops turning, no more oil pressure in the tranny, so no more lock up, no more gear engagement.
 

Angie

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ok, thanks... got it , can't be locking up then, another rabbit hole NOT to go down.... was worth a shot.

cheers all thanks
 

cbxer55

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My 07 Mustang with a 4.0 auto, had mucho trouble with the P0741 code, Torque Converter Clutch Locked Off. It also kept causing a blinking OD OFF light, which means something is wrong within the transmission. I finally paid my good friend Rick, who owns Ace Transmission in Midwest City OK to rebuild the thing, including one of his custom shift kits. Been good ever since. It required a completely new torque converter to fix. But he did a full up rebuild at my request while he was in there. $2000.
 

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