Case Study Surging, loping idle in 91 Sable 3.8 V6. Cause: Engine Control Module Symptoms Loping idle in gear, got worse as engine warmed up. Usually okay from cold start. Shifting could tend to be a little harsh at times. Engine would usually stall after WOT test. DTC: 326, EGR ckt voltage lower t...

Thanks guys, I appreciate your support on this project. I really learned a lot about engine/ transmission control. After too much time staring at the engine wondering what the heck was going on, it's good to know others enjoyed the adventure. My wife's collective comment was, "I don't care, it's jus...

Hi again. I assume you’re concerned about external noise or scope and/or setup problems. I tried a few setup changes and checked for noise from my fluorescent trouble light, but couldn’t find any problems. The back emf of 2v on the EPC solenoid seemed pretty big, but ?? I had determined earlier that...

Happy Halloween Hey, you guys are a great help keeping me thinking. I’m finally learning about fuel injection and also getting some time with the scope. Latest: From a cold start the EPC is working fine, shifts are smooth and idle is good. Over 20 minutes or so things start to fall apart. Idle is st...

I just updated my post with the pics Got 'em- thanks. I've confirmed that it's the tranny pressure regulator (EPC in the Ford book) that can be disconnected and without its switching spikes, the power lines are almost completely clean, the MAF signal is stable, and the idle is good. The EPC solenoi...

hexibot43 wrote:These are for a 1990, but almost identical..

reply test

Hi Mab No, no access to a scanner. Local parts stores only have newer readers. With the axode2 connector removed the power line and MAF hash goes away and idle is perfect. I found a couple of ground connectors that looked suspect but no improvement. I tried uploading some more waveforms but...?? (pr...

Hi again, thanks for the tickler, it got me going on a long learning process on how this fuel injection system works. And Mab, but I can't open the links (red X showing) Here’s what I think I know: Code 326 (Pressure Feedback EGR Circuit Voltage Low) keeps getting set. I think the EVR (EGR regulator...

Hi Patient is a 1991 Mercury Sable, 3.8 liter V6. Over last couple of years it will stall at idle, then run fine for weeks. Recently it has developed a surging idle and stall after shifting into gear or after warming up. Engine runs better with MAF sensor disconnected but still has occassional idle ...