Torque Converter Locked Up At Idle
 

1986 K5 Blazer. New motor (383) with carb. 700r4 transmission. No computer.

The truck sat in a field for 2 years before I bought it. I installed the new motor. It idles great in P or N but struggles in gear at idle. I found the torque converter lockup wiring harness was mangled so I wired in a new one. Now it seems to do great when cold but once warm (or once the TC engages) it goes back to the same problem. If I put it in N when stopped in traffic, it lunges when I shift back to D.

1. I see a 2-wire harness that is part of this system but don't know if it hooks in to the transmission. I originally thought this was the speed sensor but now know the speed sensor hooks in at the speedometer. Since this harness provides the ground to the TC lockup wiring harness, I added a ground wire to the harness. Could this be an issue?

2. Is my TC bad after sitting for so long?

Follow Up
 

Since I have no replies on the forum, here are my thoughts.

I think the stock torque converter is not appropriate for the cammed up 383. I am going to pull the timing cover to identify the cam so I can get specs for proper stall speed. Then I can choose an appropriate torque converter.

If anyone has any thoughts, I am still open to suggestions.

correct me if im wrong, but i dont think that cam size has anything to do with stall speed of a TC.
did you service the trans before putting it back in service? sitting for 2 years couldnt have done it any favors and it could have been messed up from the get go. have you thought about taking it to a trans shop that has an old bearded guy working there that might know what he is actually looking at since most of the kids now-a-days think that if the check engine light isnt on there is nothing wrong....

Twip, you are correct about the cam not having anything to do with stall speed but the larger cam will require a higher idle RPM which is going to be fighting the converter. This is most likely the problem, which is what Superman mentioned. However he said the problem only occurs after warmed up so there is a possibility that the converter is staying locked which would be evident by the engine dying when coming to a stop. The converter lockup is just like a clutch and if it stays locked it will feel like stopping a manual car without disengaging the clutch.

Start with the idle speed and compare that to the stock factory speed. Factory stall on the converter could be somewhere around 1800 so a small increase in idle speed will make a big difference. If you want to get by cheap, just throw in an S10 converter which will raise the stall speed quite a bit in a heavier vehicle as well as behind a bigger engine. Otherwise an affordable B&M converter is pretty much the same thing. 2500rpm is a good point that will give enough at idle and still get decent mileage.
Hope some of that helps even though I don't have an old beard and am still relatively young.:icon_wink:

I think you may have solved my problem!!!! Please see my post in this forum "losing my freaking mind". THANK YOU!