Hi all! I have an 2001 Ford Escape V6 3.0, about 130,000 miles. When the engine gets under high load and low RPM, before downshifting, it will shudder (misfire?). Local shop couldn’t reproduce it, but they thought it might have to do with slightly cracked vaccume hose, which they gouged me to replace. No improvement. Next they wanted $700 to replace Valve Cover Gaskets. I decided to become a mechanic and learn how to do that one myself. Sure enough, there was a little oil dripping onto one plug. I replaced the gaskets and all 6 spark plugs successfully. Still didn’t fix the problem though.
Symptoms will occur reliably when driving at 45-50 MPH with the transmission in overdrive (1500 RPM), and I begin a slight incline. The vehicle will kind of chug forward (feels like sporatic misfires) in overdrive, getting down to 1200 RPM before deciding to downshift. Generally, I can just give a little more gas to force downshift and avoid the nasty-feeling misfires. Some days, however, it is much worse, and will misfire at idle, and make me feel like I have to treat the gas as an on/off switch to keep the engine from dying. (It has never actually died.)
During a really bad day, I got a flashing check engine light. I did not check codes in time - they’ve all cleared.
I now have an ODB2 reader logging real-time data. All I can do is prove the conditions that cause the symptom: high engine load at low RPM is the recipe. Nothing seems to show a cause… I may just not know what I’m looking at :-/ . I haven’t monitored long enough to record a ‘bad’ day.
I’ve read about ignition coil issues on this engine, and weather might explain why this is worse some times than others. However, I wouldn’t expect that to be load dependant.
Most of the time it feels like the transmission just isn’t shifting when it’s supposed to, but on the bad days it seems more than transmission related. When stopped at a light in Drive, this can still occur.
Any ideas my friends?
Thanks for reading,