6.2L IAC Issues
 

Hello Everyone,


New member but longtime OSO fan.

I recently replaced my IAC valve on my MX 6.2L MPI (OM335613).
This is the second one that I replaced over the last 8 years or so but
this last one got so hot it melted the plastic end off the valve. I put
the new valve on and the engine seems to be running fine but the
valve is getting to hot to touch. That doesn’t seem right to me so I
called Mercury tech support and they told me that this valve can get
as hot as 200 degrees. I was still not comfortable that the valve was
getting so hot so I invested in a techmate pro scan tool and when I
plug in the scan tool I am able to monitor the duty cycle of the valve at
idle and when I’m driving the boat. It turns out the duty cycle was
pretty much stuck at 99.9% at all times. So I was looking at the throttle
body and it was looking a little dirty, so I decided to spray a little throttle
body cleaner on it and I restarted the engine with the scan tool connected
and now at cold startup the duty cycle is at 99.9% but once the engine
warms up the duty cycle now drops down to around 30% or so which is
what I believe it’s supposed to do. But I’m still not convinced that I have
solved the problem because when I put the boat in gear and start to
cruise the duty cycle creeps back up and at WOT the duty cycle is at
99.9 %. I would have thought that the duty cycle would actually drop
closer to 0 than climb back up to 99.9%. So can someone tell me what
the duty cycle should be when your off idle. There are no IAC fault codes
and the engine has 100% power according to scan tool. Checked surface
temperature of the valve and it’s averaging around 120 degrees.