03 175 Ficht Running Rough and Coughing at Low RPMs

[chkoch99]

Hi guys! First time visitor to your site, can you help out a newbie?

Took my 03 175 FICHT to my dealer with the following problems. . .when running at WOT (around 5200 for my boat) the RPMs would all of a sudden go down to around 4000 then slowly rev back up to around 5200, this would happen very randomly. It was also running rough between 1500 and 2500 RPM.

The dealer had it for a month and a half, nothing showed up on computer, compressions checked out ok, don't know what else they looked at. . .they finally found that I had a bad intake and a "sensor that needed adjusted".

I've had the boat out 4 times, replacing the intake seems to have fixed the issue with the RPMs going to 4000, but it is still running rough between 1500 and 2500. During my last trip this weekend, it would begin to cough once after ideling accross a cove at about 2000 RMS and one other time after running WOT after I let off the hot foot with the boat was slowing down.

I started talking to some guys and they said to check the Exhaust Temperature Sensor. I opened up the motor to check that out and I noticed the dealer DIDN'T index the plugs after he worked on the motor the last time (some had the gap facing totally away from the injectors). I also pulled out the Exhaust Temerature Sensor and it is carbed up about 1 1/2 inches from the tip and when I blow through, I can only feel air coming out of 1 of the holes in the probe.

I have decarbed the engine once a year since I have owned it, when i change the plugs, they always get indexed, and I always use the XD50 oil and the mid-octane gas.

I put a fresh set of plugs in it and am getting ready to order a sensor.

Now FINALLY to my questions. . . .

Could my problem with the rough idle been the Sensor all along?

Combined with the fact that the plugs have not been indexed for a month explain why is has recently seemed to get a little worse and developed this "cough"?

What did the mechanic do to "adjust a sensor"? Is there some setting on the computer for that? (it doesn't look to me like the the Exhaust Temp. Sensor was removed or replaced by the mechanic)

Can I clean the sensor? (I've heard of guys soaking in engine cleaner and drilling out the holes in the sensor to remove the carbon) Or do I need to just order and new one?

Is there anything else I should check as well?

Thanks in advance for your help!

[RUSTY63]

Welcome to the BBC.

He could have adjusted the crank shaft position sensor (CPS) or the throttle position sensor (TPS).

The Exhaust sensor you are referring to is the exhaust back pressure sensor connector and it can be cleaned.

I would look at the spark plugs and see it there is a white dot on the ground electrode, if not.....that could be your miss, also index the plugs.

[chkoch99]

when looking at the exhaust back pressures sensor, there is the big hole which the hose hooks to and three smaller holes in the shaft. i can only see into the small holes no deeper than the thickness of the walls. is that the carbon build up? if it was new or clean, should the tube be totally hollow inside?

i suppose i should soak in engine tuner and clean the smaller holes out with a drill bit. . .is that the right approach? is there anything i can mess up doing this.

thanks again for your help! very much appreciated!!!!

[RUSTY63]

The tube is hollow inside, clean it but do not take any metal out of it when doing so.

[SEAHORSE]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RUSTY63 &raquo;</TD></TR><TR><TD CLASS="quote">The tube is hollow inside, clean it but do not take any metal out of it when doing so. </TD></TR></TABLE>


Actually the late model exhuast pressure tubes have a ceramic filter inside them that can plug up with carbon. You can soak them overnite in Engine Tuner, but if they don't open up after a shot of air, then replace it. Don't forget to clean out the hole in the block were it mounts. A valve guide brush works well for that.

The book call for cleaning and inspection the tube every 100 hours.

[RUSTY63]

I knew you would bust me on that.....

I posted and came back to read and realized I had post incorrectly, I need some glasses.

[SEAHORSE]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RUSTY63 &raquo;</TD></TR><TR><TD CLASS="quote"> ...and realized I had post incorrectly, I need some glasses.</TD></TR></TABLE>


You need not only glasses, but as they used to say in the service "That boy needs some advanced individual instruction!"

[RUSTY63]

I could use a refresher course

Come on up and teach Old Great One, Ill buy the adult beverages...

[Bassmeister]

And the JRude boards rock on!!!! SH Ya need direktions to Riverside???? To my understanding Rus has lost a couple Alabama boys wid his direktions!!!

[toddgot5fish]

not if you like the scenic route............aka ....smokey mt national park

[chkoch99]

well i didn't see Seahorses reply until just now. . .right after I got it put back together.

took more than a shot of air and engine tuner. . .but after some scraping with a very small screw driver and washing the carbon pieces out by squirting engine tuner down the tube , it' seems to be all cleaned out, air flows very easily through all three smaller holes. do you think that will do it? or do i still need to order a new one? anyone i called said it would be 10 days before they could get one in, and i'd like to check it out this weekend.

cheers guys!