I have a 2003 Oldsmobile Aurora Final 500. Replaced the manifold gasket and Catalytic Converter over the past 4 weeks, and was planning to replace a bad coil pack this week. I do not drive more than 80 – 100 miles a week, usually less. The car ran good except for a misfire that could be felt at idle and low speeds (under 50mph). Also had an evap leak that needed to be diagnosed. Brought it into a shop (recommended by a friend) for a smoke test for the evap emissions leak.
The test showed the vent solenoid is bad. We can do the repair at home. My question is, what happens to the smoke after the test is done? Is it normal for the smoke to seem to be leaking from multiple locations in the engine?
I barely made it home from the shop which was 40 miles from my home. The CAT was glowing red, and it had all the symptoms of a plugged Catalytic Converter. As I said it was replaced 3 weeks ago. Could the ignition coil have ruined the CAT already? Or the could smoke in the fuel tank cause this?
ANSWER: No, the smoke from the EVAP emissions test would not cause any damage. First of it would not get burned by the engine to get to the catalytic converter and it is usually just nitrogen- an inert gas. The mechanic should have at least removed the gas cap to allow the smoke to be released after the test.
Im thinking the the smoke from the engine may be related to the converter that now seems plugged. The ignition coil very well could have caused the catalytic converter to get plugged that quick. Especially if if was a cheaper aftermarket converter. Raw fuel in the exhaust will burn the catalyst. That’s why it was glowing red. Raw fuel was burning inside of it.
It is also possible that that eh engine has a bad fuel pressure regulator. This along with the ignition coil problem could speed up the burning of the converter. Raw fuel would be entering the vacuum line of the regulator and going straight into the engine. This is pretty common on many GM engines including the 4.0L Oldsmobile Aurora engine. See pic below.
I would get the ignition coil replaced and pull the vacuum hose off the fuel pressure regulator to see if if it smells like raw gas. If so, replace it. Also see if the spark plugs looked fouled out. Replace as needed. Then re-evaluate the converter.
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