Can anyone recall any instances where a MacGyverism really failed and MacGyver had to go to a plan B?

Hmm... I can think of a few instances when 'Plan A' didn't work as well as Mac hoped, and a few where it worked, but the results left Mac in more trouble than he was BEFORE... but none where he had to shift to a 'Plan B'.

The closest I can think of is 'Wasteland' (probably because I'm watching it right now) where, if you consider 'Plan A' was to confront the Bartletts with the facts and ask them to quit developing, and when that didn't work, taking Bartlett Sr. on a ride to the wasteland might be 'Plan B'. That worked... but it took a 'Plan C: powerwing' to escape with their lives!

But that's really looking at things backward. Lemme give it some more thought (and watch some more eps )

Maybe Prometheus Syndrome where he tries to diffuse the bomb, then it fails and he and Earl Stringer have to run--Earl is killed--one of the best of season 7 episodes.

Yes
In "Jack of Spies" Mac tries to stop the garbage truck from crushing them, and it doesn't work.
He even says, "These should hold. If they don't, we'll go to Plan B."
Of course Shadow asks him, "What's Plan B?
His reply, "I don't know yet."

The one that comes to my mind is when Mac is trapped in the sinking boat (I think it's in "Pirates") and he has to break open the hatch. First he tries to make a hydraulic jack but it doesn't work, so he ends up torpedoing the door with an air cylinder.

oh yeah. good memory.

Darn it -- I remember noticing several times when MacGyverisms failed -- it was one of the things I liked seeing happen! But can I think of them all now? Nooo. Well, it's another excuse to go re-watch some episodes!

Here's a few, mostly Bad Bomb Moments:

In "The Prometheus Syndrome", as I recall, he had to deal with three of the bombs, and he only managed to defuse the third. I don't remember the details of bomb #2; Liz described the other.

In "Hell Week", he tries several approaches to defusing the bomb (I don't remember the specifics), and they don't work or don't go far enough -- I think he ends up with Plan G or so.

In "Tough Boys", when he's trapped in the net, he does not succeed in defusing the bomb at all. It completes the countdown and turns out not to have a detonator.

In "Off the Wall", he's supposed to have plenty of time to defuse the bomb -- and the timer hiccups when he's working on it. Without enough time to defuse it, they have to get rid of it instead.

In "Phoenix Under Siege", he tries to find Harry by retrieving the backup computer file with the location of that bomb, and finds all the backups have been deleted. Having found Harry (using Plan B), he isn't able to defuse the bomb on his first try; the hockey ticket is Plan B Part 2.

In "The Endangered", Mac isn't even able to try the intended MacGyverism (making a fireball from bar shots), because he forgot to carry matches. He survives because the bad guy's gun jammed.

Most of the entire 'trapped in a building' plot of "Birth Day" involved the failure of assorted attempts at getting out; but those weren't the specific failures of individual MacGyverisms.

I just caught another "Plan B" moment, and had to go dig this thread up again!

And guess what -- it also involves an explosion, or rather, the lack of one. In "High Control", Mac mixes up a chemical compound that's supposed to become explosive once it's dried, and detonate on impact; he uses it to set a trap that should go off when the bad guys return and step on it.

It doesn't work (possibly it hadn't dried), and they have a fight scene instead.

The stuff does work a little later, when Mac uses it for explosive power to ram the vehicle of the escaping bad guy.

Although no details of the compound were given -- as I recall, Mac just says he's mixing up "stuff" -- it may have been the same compound that he uses in MacGyver On Ice. The behaviour and appearance matched.

Unfortunately, I don't have my own copy of the book -- I borrowed Lothi's (thanks Loth!) and actually returned it, promptly. This presumably helped my karma, but it means I can't check what the "stuff" was.

Sounds surprisingly like touch powder.

Lothi dug the recipe out of the book: ammonia and iodine, mixed together to form nitrogen triiodide.

"Mix 'em together. They precipitate black crystals. While the paste is wet, it's stable. Let it dry, boom! Huge great explosion as soon as anyone touches it. No harm done. Just a big bang and a hell of a flash." (MacGyver On Ice)

Or, if you prefer:

"The material that is usually called "nitrogen triiodide" is prepared by the reaction of iodine with ammonia . . . In the dark and kept cold and damp with ammonia, NI3·(NH3) is stable. The dry material is, however a contact explosive . . . " (Wikipedia)

Spotted another Plan B moment.

In "The Ten Percent Soloution", after escaping from the mine, Mac tries to hotwire a van to use as an escape vehicle. He's still trying to hotwire it when one of the bad guys comes up -- and Mac has to punch him out instead. He never gets the van started at all.

yep, touch powder.

I remember spending a lunch period in high school making it with some friends and spending the rest of the day setting small amounts to annoy each other.

Wow, this thread has been dormant for quite a while! *wipes off thick coating of dust*

I rewatched "Trumbo's World" and "Last Stand" recently. Both episodes involved progressing from Plan A to B to C, etc. Water not enough? Try fire. Ran out of gas? Try water again . . . In both episodes, the MacGyverisms work, but the plot thickens enough to require another round.

I guess in a way, part of a MacGyverism is being flexible enough to formulate a backup plan. And looking at this thread, there have been instances where MacGyver did have to do just that.

In "Three for the road" his trick with a paper clip fails,(or something like that) I do not exactly remember what he was trying to do.

Yep, that's another one!

Mac tries to fix the fuse in his rental car with a paper clip, and it fries. He has to hitchhike -- and the next car to come along is the Cadillac convertible with the actor couple. Excellent example, not of a Plan B so much as a failed MacGyverism that requires another way of dealing with the situation -- since it's much more reasonable for them not always to work!

Thanks for reminding

I just saw Deadly Dreams (season 4) and at the beginning, MacGyver tried to open a a door with some device he created. But since the door stayed still, police officers had to open it by themselves.
I don't know if it's really a MacGyverism, but still, it's something that didn't work at the first try.

The device was a Phoenix project, so there would have been others involved in it's development, he was just executing the "field test", so it's not a MacGyverism, but yeah it certainly failed; not only failed to work, but failed to make any sense too.

Nothing beats the good old fashioned door-buster.