Strange Ignnition problem
 

My 2002 S2K's engine threw the #1 rod through the side of the block @ 102K miles; so I found a replacement motor with 37K and installed it. After the installation seemed to go well, when I went to fire it up, the motor cranked but wouldn't start.
The first thing I thought old gas, so I emptied the tank, purged the lines and ran a couple of gallons of fresh gas through the fuel lines; it didn't help. With the Honda shop manual I went through the fuel system troubleshooting routine, nothing checked out bad.
I looked at the immobilizer system, everything looked fine.
When I ran a UBD-II scan on it, it passed without any codes. But to my surprise, the engine fired up and ran beautifully with the UDB-II scanner attached. As soon as I removed the tool; the motor died.
No codes diagnostic codes are returned. But the motor ONLY runs with the scanner attached. Does anybody have any ideas?

Kevin Ledbetter

Have you ever been to Athens Georgia?

Nope, never been to Athens; why do you ask?

We had an 06 civic do the exact thing at work after I replaced the short block, the problem with it was one of the grounds wasn't making contact and the scan tool was giving it a ground. Not the same car but its a start

I'd bet it's missing a PCM ground.

I know a Kevin Ledbetter is all.... just check'n.

check the ground behind the head.

Thanks Guys! The ground wire on the back of the cylinder head was the problem. After removing the air control valve and un-attaching the wiring harness; I was able to get my hand and a wrench between the engine and the firewall to hook it up.

LOL i would never figure this out if it was me.

maybe for me too.. i would have never tried to start it after hooking up a scan tool since it didnt start before ... :D