Need Help - 91 Lumina misses and sputters

[Target Practice]

About a week ago, this car starting running and idling rough. Cheapest first, I replaced fuel filter. Ran fine for 1 day. Now running bad again. Replaced plugs and wires. Used a friend's code checker. No codes besides 12. I checked the spark to each cylinder....seems fine.

Not sure what to look at next. It "sounds" like it's missing...only running on 5 cylinders. So, it seems electrical to me. COuld it be a Fuel Injection sensor. Any ideas are welcome!
Thanks!:(

[Lobbers]

TP I'm unsure what a Lumina is :( ... a Nissan.

1. HT leads could be breaking down... due to dampness.

2. Distributor cap could be cracked & dampness getting in OR it could be old & corroded inside. Best replace it anyways.

3. It could be a small hose after falling of the air-intake system & thus 'thinning out' the mixture on the cylinder nearest where the pipe has fallen off.

4. Could be a leaking brake servo vaccum. Like point 3 above it will effect your air intake mixture.

5. Does it have carbs? if so check that the choke is properly operating.

6. Could be due to high milage & a build up of 'gunk' inside the air filter system... ahve you chacked the filter & surrounding hosings lately?

Hopefullt one of the above points will sort it out.

BTW where are you from?

[BeCos]

A Lumina is a mid/large size sedan made by Cheverolet. It wont have carbs it'll be a V6 with fuel injection of roughly 3 litres.

I'd suggest using a timing light to see if it is the same cylinder or cylinders breaking down all the time. If it is almost definitely electrical on the ignition side. You may have a faulty coil.

However if it isn't easy to decide which cylinder is missing then that'll most likely be a vacuum leak or possibly a fuel problem.

Does the engine control system light come on and if so try to record the flash sequence, then you could decipher the fault code by ringing a dealer.

It's extremely hard to diagnose any fault like this via the net. You'd be better off biting the bulitt and paying a GM service shop to investigate as it may be a common fault !