Be Well Grounded

I feel like such a doof. Last night Mitch called & we went to the Daikon Festival in Millilani. I’m a bit dissapointed, by the time we got there, there was no daikon! What’s up with that?! Anyway, on the drive out the rally FX was acting pretty wierd and doing a lot of hesitating and check engine light flashing. I pulled the code earlier which indicated coolant temp sensor.  I figured this as a shake down drive, drive home was not any better, and it seemed pretty random. Stalled a couple times at lights, but made it home. So this morning I drained the water, which was in the plan anyway, but pulled the water temp sensor. I’m not exactly sure how the ECU uses this sensor, it’s not the temp gauge sensor for the dash, it’s not the temp switch for the radiator fan, it’s not the cold start temp timer switch. The meter test at room temp was good, but I swapped it out with the original rally FX one for good measure. I then started skinning back the wiring loom to expose some of the wiring for that sensor. Visually it looked ok. I cut the connector and a length of wire off the end, then spliced in a connector from spare harness. I metered the wires of the part I cut out, it tested ok. Damn, I hope its not a problem with the wiring furthur down the harness. After soldering and heatshrinking in the spare connector, I plugged it in and started up the car. It seemed better, but then I heard the miss and saw the CE light flash. Damn! I wiggled the harness around and it indeed seemed to be associated. I worked my way down the harness wiggling it as I went to try & find where the problem was. Doh! I found it, the bolt for the grounding point for that part of the harness was loose, I’d forgotten to tighten it! I felt like an idiot, I’d spent all the morning and into lunch cutting into a perfectly fine wiring harness. Tightening it and plugging everything back in, the car ran well and I drove it out to SCCA. There still is some phantom missfiring, but it’s nowhere as bad as last night, and it doesn’t trigger the CE light. At least it’s liveable, we’ll see how it goes.