My CEL came on recently and I pulled the codes. It showed my Engine Coolant Temp Sensor, Mass Air flow, and Throttle Position Sensor.

I had previously suspected these particular items when my truck started running rough. I tried a new VAFM, no luck. I tried a new TPS, defective part, but not luck (spring was shot), I have not tried the coolant sensor yet.

After much tinkering around, I grounded the very last wire (E2 = Sensor ground, right?) Brown/black wire, and it ran beautiful. I found that that wire is the 'sensor ground' for those three exact sensors. Ironic? I no longer see black smoke from it running so rich, I can make a vacuum leak and it will die as it should (before it ran so rich I could make it run better by creating a vacuum leak)

I can ground it right to the connector in the ECM and it will run great. My question is, I don't think it's the wire that is the problem since I can put it at it's farrest end and it works fine, is there a separate ground for plug #1 on the ECM or is my ECM toast?

Thanks for the help!

 

Anybody?

 

Jay, I'm not clear what you're grounding to what when you say "I can ground it right to the connector in the ECM and it will run great." The brown wire w/black stripe should already be connected to two connectors on the ecu - E2 in the middle connector and E21 in the connector next to it. Those are "supposed" to ground through the ecu - most likely to E01/E02, the fuel injector grounds, because I think E2 is supposedly an engine ground and that's where E01/E02 ground.

What happens when you back-probe E2 on the ecu with ignition on? Do you get continuity to ground? If not, then maybe you do have a bad ecu. But if you can get it to run right by directly grounding E2, well, sounds like a good "creative" fix. My only concern would be - do you think they had a reason to not ground E2 directly? Like, could there be current leakage on all the sensors that use E2 when the ignition is off? Most multimeters will measure DC amps and milliamps - I would want to check E2 w/ignition off to make sure there is nothing flowing.

 

Wow Jay.. I am having this exact problem... right down to it running rich and smoking. Same engine codes and all... I have not got mine resolved as of yet either. I still have a few more things I need to test once I get some more time