Anyone familiar with the older Duramax engines? Plug in ect and runs like crap?

[stephen4785]

Friend of mine has a 1996 6.5 duramax. If you unplug the ect sensor it runs fine but as soon as you plug it in it runs like crap and will barely idle. He's replaced the sensor but no change. Im guess unplugging it causes the computer to go into open loop and when you plug it in it's in closed loop and somethings causing problems. I thought maybe one of you guys had run into something similar.

[Sean88gt]

No he doesn't. He has a 6.5 GM diesel. Duramax didn't exist until 2000/01.

And those engines ran like shit from jump street.

[Cooter]

I'd recommend leaving it unplugged

[Mysticcobrakilla]

Just be glad you found one that runs.

[stephen4785]

Id think I figured it out. with the coolant temp sensor unplugged the computer runs a preset timing for the injection pump. with it plugged in the computer goes into closed loop. the guy change the cylinder heads and remove the injection pump so I think the injection pump timing need to be verified or adjusted using a scan tool. I'm going to check the timing tonight.

[71chevellejohn]

Or it could be left unplugged....

[JC316]

Just be glad you found one that runs.

211K on mine and running strong. They're actually nice engines once you fix a few things. Utter slugs and no room for power improvement, but reliable and get decent MPG's.

[Mysticcobrakilla]

211K on mine and running strong. They're actually nice engines once you fix a few things. Utter slugs and no room for power improvement, but reliable and get decent MPG's.

You've got it figured out. I'll leave this be.

[fastwhite99gt]

Have to set the timing with the scan tool. It's extremely picky on the 94-2000 models.