Immobilizer issues?

A couple of times in the last month, my bug has fired and immediately died after releasing the key. It has always gone on the second or third try. One other time, it started first try but gave me the flashing immobilizer light for the remainder of the trip.

Any thoughts on how to avoid getting stranded by this? I do have a spare valet key, so could carry that with in case it is just the chip in the fob that is slightly damaged.

Assuming no cluster or key mods/changes recently, might try disconnecting the battery.
I believe there is a small bit of electronics near the ignition switch that talks to the fob.
It sounds intermittent, which always makes it tough, sometimes borderline wire damage can do that.

The immobalizer will allow the car to start normally *and* run normally for 3-5 seconds, and then shut down the engine but leave the immobalizer light flashing.

That doesn't sound like the symptoms you're describing, at least the first couple instances?

Symptoms sound like ignition switch electrical failure.

It is very intermittent so far, yes, and no cluster/key mods. I've seen varying descriptions of the immobilizer shutoff, from 0-5 seconds, so I wasn't sure about that. I'll read up more on the ignition switch - looks like a pain. Any suggestions for further diagnostics?

Black lead from ignition switch feeds power to Ecu and other things. Fuses 5,6,29,31, 9, 11. Check to see if power drops when it quits. If it does the switch is dropping the power. They can be intermittent at first failures.

I have seen more melted connector issues at the ignition switch than the actual switch itself. Easy enough to check, just have to take the column covers off.

Worst part is splicing in a new assembled pigtail connector, as there is not a lot of real estate to stuff a wad of connectors, but it is doable. I've done a bunch of 'em.

I am not sure this would have anything to do with an immo though. Any immo issues I run into I usually end up just having it deleted from the ECU. I have had a few spaz keys do this, too. You may try one of the other keys and see if it still happens.

I ignored this for a month with no recurrence, but today I had to crank 4-5 times before it would stay running. No immobilizer light. Seemed extra smokey while trying to start as well, not sure what that means.

I will take a look at the ignition wiring when I get a chance. Is it consistent with switch problems that it only has trouble starting, and never dies while running? Seems like if the switch or connectors were getting flaky in the 'on' position, it would cut out when I hit a bump going down the road.

One idea: I am going to check to make sure the ASV is moving freely. Assuming I didn't imagine the extra smokey start, that would be consistent with air starvation. I did swap in a forum member's old leaky EGR valve last fall, because the diaphragm in mine had failed completely.

If the ASV is stuck closed (dirty inside) the engine should crank faster.
Not enough air could be causing the 'extra Smokey start'

Yeah, it wasn't a fast crank/no compression situation, maybe stuck halfway closed? Awfully hard to troubleshoot when it only happens once a month.