Ol' Mountaineer
Member
- Joined
- January 8, 2014
- Messages
- 32
- Reaction score
- 9
- City, State
- NY
- Year, Model & Trim Level
- 2000 Mercury Mountaineer
Hello fellows! Got a small conundrum here, and hope someone's willing to help out.
My 2000 Mountaineer with 187k on the clock just got a new (stock style) exhaust from the headers back. All 4 O2 sensors are new. EGR valve & gasket, upper plenum gasket and elbow to plenum gasket, fuel pump and filter, all new.
So, here's the issue: I can't seem to get the PCU to reset (need all but the last 2 reset here in NY, since it's a 2000) before pesky lean bank codes show up. The last few years I would just put about 50 miles on it after clearing any codes and pull in for an inspection... no problem. Then, often enough about a mile away I'd get an 0401! But at least I was inspected for another year.
This year I'm having much more trouble... though the vehicle actually runs fine! Quite smooth in fact. (Except I'm getting as much as 5mpg less than should get.) The other day I put about 200 miles on her with no codes. The next morning I carefully start her up... perhaps superstitiously, first turn the key just to initiate the fuel pump a few seconds, then just allow a few turns of the starter and I back off, wait a second or two, then again a few more turns (trying to avoid a "lugging" start, which happens half the time anyway)... it seemed to start up fine (idles about 800-900) and I let her warm up a few minutes... but a mile out of the driveway "lean banks"! Damn, clear the codes and try again. Almost always "lean bank"codes about a mile or mile and a half after restarting a warm engine.
Last week I had about 85 miles and one warm engine restart with no codes, pulled in for an inspection and the guy checked to see if the PCU had reset. Whoops, 5 items had not reset yet! So question 1: what's the deal with that? Exactly what does the car have to go through to reset the PCU... apparently 50 miles isn't enough anymore!
Anyway, the guy told me the PCU needed the car cold again, and to start it and idle for a while as it warms up the O2 sensors. Next time around, I've laid down some mileage with no codes, shut her down... start up carefully in the morning, idle for about 20 minutes before putting it in gear. By the end of the driveway... lean banks! Reset and drove 65 miles without a code. But also without enough resetting of the PCU!
Clues: 12 -14mpg when it should be 18-19. Lugging on startup, like not all cylinders firing... then catches up (tried a couple bottles of injector cleaner). Occasionally the brake pedal gets soft (thought it could be a leaky caliper, but maybe brake booster vacuum?)... I don't get a "brakes" warning light. If the freeze data helps, I have it.
What's wrong with this thing... if the banks are lean it's not an air leak or I'd get the code constantly, not just after starting up. Any and all help will be greatly appreciated.
Regards, Bob
My 2000 Mountaineer with 187k on the clock just got a new (stock style) exhaust from the headers back. All 4 O2 sensors are new. EGR valve & gasket, upper plenum gasket and elbow to plenum gasket, fuel pump and filter, all new.
So, here's the issue: I can't seem to get the PCU to reset (need all but the last 2 reset here in NY, since it's a 2000) before pesky lean bank codes show up. The last few years I would just put about 50 miles on it after clearing any codes and pull in for an inspection... no problem. Then, often enough about a mile away I'd get an 0401! But at least I was inspected for another year.
This year I'm having much more trouble... though the vehicle actually runs fine! Quite smooth in fact. (Except I'm getting as much as 5mpg less than should get.) The other day I put about 200 miles on her with no codes. The next morning I carefully start her up... perhaps superstitiously, first turn the key just to initiate the fuel pump a few seconds, then just allow a few turns of the starter and I back off, wait a second or two, then again a few more turns (trying to avoid a "lugging" start, which happens half the time anyway)... it seemed to start up fine (idles about 800-900) and I let her warm up a few minutes... but a mile out of the driveway "lean banks"! Damn, clear the codes and try again. Almost always "lean bank"codes about a mile or mile and a half after restarting a warm engine.
Last week I had about 85 miles and one warm engine restart with no codes, pulled in for an inspection and the guy checked to see if the PCU had reset. Whoops, 5 items had not reset yet! So question 1: what's the deal with that? Exactly what does the car have to go through to reset the PCU... apparently 50 miles isn't enough anymore!
Anyway, the guy told me the PCU needed the car cold again, and to start it and idle for a while as it warms up the O2 sensors. Next time around, I've laid down some mileage with no codes, shut her down... start up carefully in the morning, idle for about 20 minutes before putting it in gear. By the end of the driveway... lean banks! Reset and drove 65 miles without a code. But also without enough resetting of the PCU!
Clues: 12 -14mpg when it should be 18-19. Lugging on startup, like not all cylinders firing... then catches up (tried a couple bottles of injector cleaner). Occasionally the brake pedal gets soft (thought it could be a leaky caliper, but maybe brake booster vacuum?)... I don't get a "brakes" warning light. If the freeze data helps, I have it.
What's wrong with this thing... if the banks are lean it's not an air leak or I'd get the code constantly, not just after starting up. Any and all help will be greatly appreciated.
Regards, Bob