I passed the emissions test easily but failed because there was too much visible smoke at high RPM (I’d think that would redound upon emissions - wrong again.) The guy was sure I just needed new plugs and wires, so I bought them and an air filter. I replaced the fuel pump and filter the day before, the oil and oil filter the day before that, the PCV valve last week - have I missed something?
He’s right: the exhaust at high speed is sooty. That’s not the kind of thing I look out for, but after I installed the new plugs and wires and air filter, I started it up and pushed the pedal all the way down: I left a big spot of soot in the pavement.
I got a new muffler and tail pipe 4 years ago; he passed the catalytic converter. Everything under the hood looks okay: no drips, no broken wires or hoses or connections. It’s rated at 700 idle speed, but stalls out that low since I put the new fuel pump in. Could a wrong fuel pump cause this symptom?