1999 optimax dfi throttle sensor alarm

[tbrandon]

I'm reasonably certain I've tracked this down to a bad throttle sensor and could use some help as in how to test the sensors as well as where they are on the engine.

I edited my original post due to it having a very vague title.

Thanks, Tom

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I'm getting an alarm check engine light randomly and intermittent beep.

1. at wot after 30 min took me into limp mode, cut throttle to 1000 rpm alarm quit and ran normally for a while....

2. went through a no wake zone came out of the hole to get on plane got another intermittent alarm after cutting back to 1k again was fine.

3. docked the boat idling with wife in boat as I got the trailer and alarmed again, shut it down and ran fine again.

Always an intermittent beep and a check engine light.

After that I took it to be hooked up to a meds system and got no codes, disconnected the water temp sender and Immediately got a code until I turned the key off then back on and then all error codes are cleared.

So how to proceed?

Could I run the motor, till i get back to a dock and save the code by not turning it off as in shutting off the fuel keeping power to the computer or as I plan to keep the boat at least 10 + years buy a ddt or is the computer on the motor bad?


As always any help at all would be greatly appreaciated.

Tom

[tbrandon]

To add more info... It seems that the problem is a throttle sensor, could anyone help with info as to how to test them to find the bad one and posibly even where they are located on the engine?

[tbrandon]

bump

[schematic]

Optimax is a fairly complex system. You need a manual. TPS is usually found on the end of the throttle valve shaft. Typically has 3 wires. 5 volts, sensor ground and signal. Use a voltmeter to determine which is which. The signal wire should vary with throttle position. .7 volts to 4.5 volts is typical. The voltage should vary smoothly with steady throttle position increase. .7volts at idle to approx 4.5 at WOT.

Get a free manual for your model here: http://forums.iboats.com/mercury-mariner-outboards/do-you-need-any-mercury-manuals-pdf-format-309079.html

[tbrandon]

Thanks for the reply, so far I have a seloc manual that indicates there is only 1 TPS sensor, a Merc manual that gives a great view of how the sensors are put together on the engine as if they need no adjustment of any kind and the link you posted that I will need more time to digest.

After giving it a good bit of thought I realize that even if I did find an accurate detailed trouble shooting process for them I still would have a mess because it's so intermittent, that said I ordered both, that should solve the problem unless there is a detailed way to adjust them.

Any further input from you or anyone would still be well recieved.

Thanks, Tom

[schematic]

sensor are expensive. I would test them thoroughly before ordering them. If its out of your comfort zone, it would be wize to take it to a competent repair shop. The hourly rate may be high but it will save you throwing your money away on uneeded components.

good luck

[tbrandon]

The fact that it is intermittent has driven the pro boat guys nuts lol for some reason the computer is not saving the error codes so therefore the ddt/meds are no help and yes they are terribly expensive but I'm kinda lost as to how to proceed?