98 12v auto, has stage 1 sdx injectors, delivery valves and 3k gov springs plus boost elbow.

Factory style lift pump, holds 20psi at idle and 2200 rpm

Idle is low but still stalls even when using your foot for low idle compensation.

Normally It would slowly die down in drive then abruptly stall (not moving) and coming to a stop it'd stall. This time the truck was under gradual load (no wheel speed) pulling when the truck cut out completely. Wastegate fluttered and all, I have not had a chance to verify the fuel shut down solenoid isn't causing the abrupt kill, but the truck starts right back up.

I'm leaning towards the torque converter on its way out, the transmission ruptured a line going down the road and pumped itself dry. Filled it back up after makin the repair and it's ran for 2 years since. I'm thinking it's starting to show its wear from that incident. As far as I can tell there is no transmission slippage, but it does like to start out in second after coming to a stop and doesn't downshift right away.

I'm going to add a click to the gov springs and make sure they're set evenly with a caliper then adjust the idle. We've had the low idle stalling issue with this truck forever and bumping the idle alleviates the issue but the truck then fights the brakes.

Go ahead and throw some ideas out there or let me know of you guys agree with my presumptions and plan of action?

I'd rather not shell out 1500 for a TC and another $500 for a refresh plus shift kit, which it rightfully should have had last time it was rebuilt. It isn't my truck and the owners pockets aren't very deep. Appreciate it fellas.


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Does it run for the same amount of time everytime or sometimes longer than the other?

 

Inconsistent, also thought of a wacky wiring circuit/PCM on its way out; the speedometer likes to peg 120 every now and then. If the PCM is screwy it could theoretically lock up the torque converter correct? But the PCM has nothing to do with it starting in second.


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if the converter locks up in 2nd while not moving it would stall like you dumped the clutch in third with no throttle!!! you would know if it were doing that. how low is your idle? mine would stall at 650-700 once i but the new converer in. i now have it around 850 maybe a fuzz high but it doesnt stall when you come to a light.

 

It stalls just like you turned the key off, minus the slow stumble the old 12v's have. The initial low idle stall almost acted like the converter was slowly getting tighter then ka-put.


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does it do it at operating temperature?

 

Stalls more frequently hot.


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When the pump barrels and plungers wear it will be more noticeable hot than cold. The only problem with that theory is u said it starts right back up fine, correct?

 

I believe so, just a little pressure on the pedal. Very common for the 12v's. I've always thought if it was an injection pump issue it'd show cold from the loose tolerances from contracted steel, and diminish once warm. There isn't a skip or rough cylinder in the truck, often contemplated having the pump benched as my theory for the pressure on the throttle is to turn the plungers ever so slightly for port closure; otherwise it acts like the shut down lever is being tripped. The barrels and plungers may not be worn more so as the governor linkage so the plungers aren't sitting where they need to be. Turning barrels and shimming the pump correctly on a bench should cover that issue right up with out having to keep turning the idle up, we're constantly adjusting the idle on this thing as its always getting lower over time. Truck is like 2k miles from 300k.


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I do know for certain if it's worn it will be worse hot than cold. With a starting issue that's how u know if it's low compression or a worn pump. Low compression starts easier hot, worn pump starts easier cold than hot.