Hated on ECM data until it saved my bacon on a tough job

I always thought real mechanics figured things out by feel and sound, not by staring at a screen. Engine computers seemed like a way for manufacturers to make things harder. Then I had this pickup in the shop with a rough idle. I was convinced it was a fuel delivery issue based on the sputter. Checked the pump, the lines, the filter, everything looked good. I was about to tear into the injectors when my buddy said to just scan it first. The code came back for a bad camshaft position sensor. Swapped it out, and the truck ran smooth. Now I scan before I touch anything. It cuts out so much wasted time.

3 comments

3 Comments

the_dylan17h ago

Man, I feel this so hard. I swore by my timing light and vacuum gauge for years and thought scan tools were a crutch. Spent a whole afternoon once chasing a miss on an old van, replaced plugs, wires, the coil, you name it. Finally plugged in the scanner on a whim and it was just a lazy downstream O2 sensor. Felt like a total idiot but it changed my whole process. How many hours do you think we've all wasted fighting the computer instead of just asking it first?

nguyen.elizabeth14h ago

My buddy Rich did the same thing with his truck (he's a vacuum line purist, you know the type). He chased a rough idle for two days, cleaned the throttle body twice, even redid the intake gaskets. His cheap code reader showed nothing, so he assumed the computer was fine. Borrowed a real scan tool and found the throttle position sensor was barely sending a signal at idle. All that work over a five minute data stream check. He won't even open the hood now without plugging in first.

the_matthew14h ago

Saw a guy at the shop last month replace a whole fuel pump assembly on his Cherokee. Three hours of swearing. His buddy finally asked to see the live data, found a chafed wire to the pump relay. Five cent electrical tape fix after all that.