1996 2200i misfire. high idle

[dzldoctor]

Have a 1996 tige 2200i boat has been great all season. Week long camping trip the boat starts to run rich and idle high. All gauges in the norm. Unplugged a few of the sensors and no change in operation. IAC,MAP,TP none of the sensors made a change in operation. Is there a way to get codes or any other info of the system? The machine would backfire under load, light accel or idle was ok but with rich condition. The engine is the 350 multi-port efi. about 500 hrs. New plugs and fuel filter last fall.

[boatwakes]

Running rich is usually related to the coolant temp sensor but could be a few other things. Higher idle tends to be a throttle position issue, any backfire would be timing related (most likely ignition sensor) or stuck intake valve. Start with the ignition sensor, if it hasn't been updated and see if it takes all the symptoms away. The diagnostics port on that engine is located near the ecm and if you're in southern california, I can plug it in and scan it for you.

[dzldoctor]

Is there any software or scan tool that I can purchase to talk to this machine? I don't mind spending money on tool if its reasonable. Any way to self test with a jumper or anything like that?

[dzldoctor]

I'll get the ignition sensor, but I know there's more of an issue here with the high idle and running rich also.

[TeamAllen]

I know of two scanner type software companies for Mercruiser.
http://www.rinda.com/marine/marine.htm
http://www.obd2allinone.com/sc/detai...item=mefiscan1

I recently purchased the MEFI 1 and was messing with it a little yesterday on the boat. Next week we are taking it with us for a week at Lake Powell and will spend some more time checking it out.

[dzldoctor]

Done some messing around with a volt meter. Found the tps to be out of whack. The key on engine off voltage was .02 and wot was .59 should be around .9 and about 4.5 to 5 at wot correct? That obd software scan and tune looks interesting.

[TeamAllen]

Yah, the scan and tune is more than I want to mess with. You are a brave man!
I met the guy selling the software. He is semi local to me, so I drove and picked it up. He said I could always upgrade to the tuning software for the difference in cost. He just works out of his garage.