Rough idle after smoke test

[DaveRad]

Hey everyone, I’ve been trying to diagnose a P1126 recently, and I ran a smoke test with a machine I bought online. I couldn’t spot any leaks or anything like that during the smoke test. After I completed the smoke test, I left the car in the garage overnight, and didn’t start it, to ensure any extra smoke left the engine before I started it. My biggest concern now, is that when I start it, it has an extremely rough idle. When I turn the car on, it runs normally for the first 3-5 seconds, then gets progressively worse. What can do I do from here? Everything I touched is back in place.


1998 986

[The Radium King]

unplug your maf. if it fixes itself then you got smoke goo on your maf and need to clean it.

[DaveRad]

Originally Posted by The Radium King

unplug your maf. if it fixes itself then you got smoke goo on your maf and need to clean it.

Just tried this, it runs maybe a bit better, but still very low rpm at idle. One very weird thing: I was giving in a bit of gas to experiment, and heard a loud-ish sound from the engine bay. Turned off the car, then I turned it back on for just a few seconds. The rpms climbed a lot smoother when I gave it gas, but I didn’t experiment much because I dont know the source of the sound yet.

[DaveRad]

Originally Posted by DaveRad

Just tried this, it runs maybe a bit better, but still very low rpm at idle. One very weird thing: I was giving in a bit of gas to experiment, and heard a loud-ish sound from the engine bay. Turned off the car, then I turned it back on for just a few seconds. The rpms climbed a lot smoother when I gave it gas, but I didn’t experiment much because I dont know the source of the sound yet.

Does anyone have any info on this? I’m now getting high short term fuel trims, and when I drove it random misfire. P0300 P0304 P0305. What’s going on?

[Gilles]

Dave, I have never done a smoke test before but if your car was working properly before the test, there is a possibility that you unplugged (or cracked) one of the vacuum hoses and now you have a vacuum leak..?