Surging at idle on '94 Legend?

Hi. My neighbor has a '94 Legend with 162k miles. I move the car sometimes as we share a diveway.

When cold, the car starts fine and the idle speed slowly increases to fast idle (near 2k rpm?) for about one minute, then suddenly the revs drop to 1500, quickly climb to about 2300, then drop to 1500 again and this cycle continues as 800-1000 rpm surges. When shifted into a drive gear, idle smoothes out at around 1400, but surges to 3200 when the car is shifted back into P or N, then continues surging between 1500 and 2300. I don't generally move the car when its warm, but when he pulls in the driveway after work the problem seems to have largely resolved itself.

He had a head gasket blow out a while ago and it was replaced by the local Acura dealer. The gasket blew out on a short trip and he stopped very soon after it blew...but I don't know whether major engine damage occurred. I like to think the dealer would have advised him of that if they found it.

For comparison, I own a '97 v-6 Explorer that had an intake gasket leak - the engine also surged but there was no pattern...it surged, stumbled, stalled, spit, sputtered etc, but it was very different from this Acura problem. The Legend surges are smooth, predictable and precise, almost like they were programmed into the warm-up sequence of the car's computer.

Any thoughts or suggestions are appreciated.

Thanks,

-Keith

Did you ever find out what caused your surging idle? I have the same car and problem.

This is a common problem for hondas.. Read this write-up.
http://www.hondafactor.com/v2/f-hf-technical-garage-275/t-oscillating-idle-perhaps-this-will-help-5184.html

I had the same surging problem with my 1995 Legend. The dealer replaced the speed sensor. That did it for me.

I had the same problem with my 1995 Legend. The dealer replaced the speed sensor. That did it for me.