Specifics:
1997 Honda Prelude
5 Speed Manual
150k Miles
Had the ignition recall done
BONE. STOCK. H22A4. No intake, no exhaust, headers, nothing. Period. Not even a drop-in filter.

The Weather:
I live in Ohio, and recently it's been super cold, then warmer, then wet. then warmer.

How I drive this car:
I commute to work 8 miles each way through the city. Nothing more.

The Problem:
For the last several months, this Lude has been driving exceptionally. Burns a little oil, but they all do. No loss of power whatsoever. Otherwise, it is incredibly quiet, no knocks, no Check Engine Lights, no overheating, nothing. It is the smoothest H22 I've ever been behind, and that is the reason I purchased this car. That, and the comprehensive list of service receipts that came along with it dating back to 1998.

Yesterday, ABRUPTLY, about halfway through my commute, when the car was warm, it stalled when I placed it into reverse and backed out of a parking space. This was followed by a "hard start" where the car had to crank many times to turn over. I would then drive it a bit forward, and if I didn't give it more throttle than usual, it would die again. I finally made it down the street and around the block, but freaked out when I saw a stoplight, as I was certain the car would stall if it dropped below 500-600 RPM. I limped my way to work, no CEL, no issue, and parked. I came back out on my lunch after the car had time to cool, and whaddya know? It started fine, acted as if nothing was wrong, and drove away. Drove the car home from work, and when it had time to warm up again, it nearly stalled in an intersection, bogged a bit, but I gave it some stick and it went right home. Experimenting a bit at home, the car would be incredibly difficult to start until it cooled off again, at which time it would fire right up.

I'm stumped. There is no fluctuating idle. No loss of power. No problems on the highway or when driving. VTEC will engage.

Anyone have any ideas? Thanks!

TL;DR - Car will run beautifully, but when it gets up to temp, it'll stall when taken off load by the clutch, resulting in difficulty starting.

Thanks!

 

Also adding this into the mix, though I don't know how it would have any bearing on the problem, but I was just a "Hit and Run" victim right before this started as well. 2 inch deep by 4 inch wide crater in my hood left by a large vehicle, driver side. I've been scratching my head trying to think if this could have dislodged my battery or a grounding wire...

I'M LOSING MY MIND OVER THIS, AND I REFUSE TO DRIVE MY OTHER CAR IN WINTER. [screams inside]

 

Check your main relay and or all fuses. Also check your IACV while your at it and clean it, plus clean FITV if your throttle body has one.

 

I certainly will! Thank you!

I'm also thinking of doing a compression check, but the car isn't leaking coolant, and an internal HG failure causes a "no start" situation, I believe.

Anyone think it may be O2 related? Or would that throw a code!

 

Shot in the dark, maybe your ignition coil is about to fail.

 

Car drove fine today in much colder weather (18 degrees F this morning). When I pulled up to a stoplight there was no stall, but I noticed a very slight "bounce" to my idle. I'm gonna go with either the Main Relay or IACV, as it only happens when it's warm.

Time to fire up my soldering iron, boys. Haven't done that since I had a CRX 12 years ago... I think I'm regressing at life.

 

My thoughts are main relay, map sensor, or a coolant sensor going bad.

 

check you iat sensor on the driver side of the intake manifold. Super easy to remove and check. When mine exploded (literally) my car would run like how you described but sometimes would fall flat on it's face and feel like I slammed the brakes on. It's easy to check, probably not the issue but you never know.

 

Starting Problems

Main Relay Fix, Troubleshooting (Honda, Acura) and how to solder

 

Just to resolve this for anyone that googles it in the future:

The issue was that the car would not "catch" at idle speed coming off of engine load after it had warmed to operating temperature. I spent a few days watching the tach carefully while I drove and monitored the temperature. Yesterday morning when my car had warmed up, I popped the hood and unplugged the IACV connector from the sensor just briefly. The car stumbled for a moment as I wiped the male and female connectors clean. I then plugged in the sensor and shut off the car. Since then, I've driven approximately 50 miles and have yet to have a recurrence. I'll post pics of the valve when I take it off to clean it this weekend. It appears that it was simply moisture in the plug.

Thanks!

 

Sounds like you just need another pigtail. Yours is probably breaking the two inner pins.

This happened to me before. Just cut off a pigtail at the junkyard and splice it in.

 

I had the plugs all unclipped today to clean and inspect. They're all in good shape. There was an awful lot of moisture-related salt and grime in the engine bay. A good spray of all the plugs with electronic connector cleaner and a scrubbing of the battery terminals had it running smooth. I also topped up the radiator and bled the system. All good.

The plugs ended up being fine, but I can see where they could cause serious problems if not.