Alright, tired of messing with this and want some 2nd helpful opinions. I've noticed a decrease in mpg and actually made it ping once pretty bad when I got on it hard. It also has a strange idle issue when it gets super cold out and first start of the am the rpms will fluctuate between 2k and almost dying (~500). Once the motor warms up the idle is fine and it won't do it again all day, even after sitting 8 hours at work. Drives just fine other than that.
Since the MIL bulb is out, I broke out the scan tool and got 5 codes back as follows:
P0137- O2 low voltage sensor 2
P0171 (twice)- Lean bank 1
P0405- Sensor A EGR circuit low input
P1404- EGR stuck open?
What I have done so far:
Checked +5v reference at the gray wire of egr plug. Have +5v with key on
Removed EGR valve and checked pintle operation- not stuck at all- moved freely
Checked gas cap- the seal has small cracks starting to form in it, could be a bit loose fit on the neck
Checked wiring to rear O2 sensor- Not damaged as far as I can tell but it's f'n cold and I didn't actually probe it with a meter and I don't know where to check it, lol..
Replaced the upstream O2 sensor a few months back
What I do know is that I must have a crack in the rear manifold somewhere as when I first start it up I can hear an exhaust leak. It stops as it heats up. Have a leak in the resonator that I just found. Original cat on it as far as I know, which now has 360K on it along with the rest of the exhaust. I banged on the cat with my hand and heard what sounds like a loose washer or something bouncing around. Will have to jack it up so I can see if it really is something in the exhaust or just a loose/rusted part outside the cat rattling around. It's possible that there is gravel trapped somewhere as I live in the country and frequent gravel roads, but I've been suspecting the cat for a while now.
To start out, I plan on replacing the gas cap and clearing the codes and see what comes back. If it comes back for EGR, is there a re-learn for it? I swapped on a spare one I had at some point but didn't do anything other than bolt it on and go.
How do I check voltage at the rear O2? I should probably just replace it as when I got the car it had this code so I stuck an O2 sim on it to clear it. The O2 sim died and I reconnected the O2 sensor again.
My scanner can read live data so if there is anything you want me to look at then please let me know and I can post it up.
