I wanted to add a little information about some recent trouble shooting. A few months back Willem started experiencing an infrequent miss at highway speeds, it would happen about once per trip. Fast forward to these last few weeks and swapping in a rebuilt transmission and the miss was so frequent the Bronco wasn’t drivable on the highway. With Garry’s (EFI Guy) help we started trouble shooting the systems on the Bronco to narrow down the problem.

Motor - verified compression was good on all cylinders.
Fuel system - verified fuel pressure was good at all engine loads and vehicle speeds.
Ignition system - found 2 spark plugs that didn’t look quite like the others and replaced the wires, also found one coil was acting up and replaced it as well.
EFI Sensors - confirmed MAF, cam position sensor and crank position sensor were good.

After all this was corrected or confirmed the miss still existed, from many test drives I noticed it was happening at a fairly narrow road speed of 64-72 mph, the engine RPM didn’t seem to matter. So on a test drive I pulled over and unplugged the speed sensor, we use the pass through version that sits between the speedo cable and the transfer case, and BINGO the miss stopped.

After consultation from EFI Guy we starting verifying grounds in the EFI harness and noticed the harness only had 2 grounds, not 3 and my ohms were high on the ground pins. I added a ground at the speed sensor and replaced the sensor.

I’m happy to report the miss seems to be gone, I’ll drive it a bit more at speed to confirm, but wanted to let you all know the outcome and thank Garry for his guidance.

Oh man-- glad you found it. I feel like when it comes to electrical, I just start seeing numbers floating around like in The Hangover.

Counting-Cards.jpg

Wow, what a way to track it down! Glad you got it fixed! Any idea if it was the ground or a bad sensor?