I've conquered my WUR and have adjusted the CCP to an optimal pressure. I have also been playing around with adjusting the WCP. Currently it's set at 40psi because my car ran very nicely with that setting a few weeks ago, but the car only ran well with that setting for a 10 mile duration or so. My car is an ROW with a 069 WUR, so I am aware that it should be set around 48 psi. Regardless, I can set my WUR's pressures, and it will hold. I give this detail because the WUR comes up when diagnosing fuel and air questions.
Anyway, I have been chasing a low rpm misfire for quite some time. From a cold start, the engine will start to misfire resulting in backfires through the exhaust. I have headers and a low restrictive muffler, so the backfires are very audible. The backfires occur during mid rpm throttle.
Things I've done:
Adjusted WUR
Checked coil - good
Compression check - very good results
Checked for vacuum leaks - replaced air box, seals, gaskets, etc. No detectable leaks
Verified that injectors spray evenly.
Serviced the ignition distributor
New ignition wires
Newer spark plugs, cap, and rotor
New fuel filter
I have to admit, that I have been messing with the AFR. Truthfully, I have been ever since I bought the car because of the issues it had from the beginning. Things are getting sorted. I have been tuning it by ear. Here's my latest observation: the sensor plate will sometimes start to oscillate very quickly if I adjust the AFR counter or clockwise, and sometimes it starts to oscillate if I blip the throttle. I can temporarily stop it from oscillating by slightly pushing up on it, blipping the throttle, or changing the AFR. Once it starts oscillating, the engine starts to really misfire.
One more thing: I have changed my spark plugs three times recently, and every single time #1 and 4 are carbon/soot gunked. The rest look good.
I have done some research, and I found a couple of old posts that point to the fuel distributor as being the culprit. I want to be more clear on this before I send it out for refurbishment.
There's two more things I will probably do: Check the fuel return lines near the tank and check the oil breather hose for holes. During the process of reinserting the engine into the car last September, the breather hose got caught between the engine tin and chassis.
I know this a lot of information. I wanted to make sure I covered everything I can think to eliminate possibilities. Thanks in advance for any insight you can give me.