Picked up a 87 2500 GMC runs awsome except when its warmed up it wants to stall out when idling and for some reason it idles at 1k'ish. 4sp Manual if that helps.

I pulled the egr but it is in perfect shape, also looked at the plugs and wires every thing seems in order there also...

Threw three codes 12, 24, 43

12 is normal from what i understand

24 (the speedo isnt hooked up yet, however it will just stall sitting, so i am not inclined to think that it is the problem)

43 is kinda weird it said timming retared for to long (feels like the motor isnt getting to much timming advance) But I dont know where to go with this one!

also if you blip the gas as it starts to drop in rpm it will recover and run fine at idle for about 1min then it starts all over, also the truck starts up real quick right after every time it stall (starts up quick any time acutlly...)


any help is appreciated!

Picked up a 87 2500 GMC runs awsome except when its warmed up it wants to stall out when idling and for some reason it idles at 1k'ish. 4sp Manual if that helps.

I pulled the egr but it is in perfect shape, also looked at the plugs and wires every thing seems in order there also...

Threw three codes 12, 24, 43

12 is normal from what i understand

24 (the speedo isnt hooked up yet, however it will just stall sitting, so i am not inclined to think that it is the problem)

43 is kinda weird it said timming retared for to long (feels like the motor isnt getting to much timming advance) But I dont know where to go with this one!

also if you blip the gas as it starts to drop in rpm it will recover and run fine at idle for about 1min then it starts all over, also the truck starts up real quick right after every time it stall (starts up quick any time acutlly...)


any help is appreciated!

my truck the same thing and so check your timing and set it to ten degrees and make sure you pull the plug on the timing plug by the brake booster and take your iac or idle air control module out and clean it or go down to autozone for 30.00 and if that doesnt change it. try the map sensor and also reset the computer and unplug the battery before changer the map and iac. :flipoff2:

Code 43: Check the wires from the ESC module to the ECM. Check the wires from the knock sensor to the ESC module. Check for a loose connection. Replace the knock sensor and/or ESC module.

Also, if you are resetting the timing, disconnect the ECM, brown wire by the booster, and set base timing to zero degrees advance. Reconnect. The ECM handles the rest as far as timing goes.