Possable TPS problem on opti ????????

[bassman82]

Well let me start by saying I have had the worst luck with boat shops . This is my first big bass boat and motor I own a 2000 nitro with a 200 opti on it I am the second owner first owner went though all the crap with recall etc. Anyway been a great engine. Have had it a lil over a year with not the first problem. Well about 3 weeks ago the motor had what sounded like a miss . pulled plugs looked really black so i changed them out miss gone at this point engine ran fine for about two outings . I was running back one afternoon I had been putting around alot so i thought Id blow her out Well at wot I notuced a slight drop in rpms and lost 7 to 10 mph off top end . Well done everything I could bye the service manual. No change took it in to the dealer ooooooo no not the dealer , Well after about 2 weeks Im told well its the thermostate on the port side stuck open that sides running to cool causeing the power loss . Well I can go for that How much ummm about 300.00 cause mercury does nat make the 120 therm anymore its a 130 and you have to have the new covers. Well I mean if you say so i guess fix it. Well get a call your boats ready but Its showing a tps fault on the ddt ?????????? I ask umm your just now seeing this . Well it just happened I was running the engine after putting in the new therms and it just stut off and wouldnt crank back up ....umm do what my next question. Well the manual says if theres a tps fault youll get a beep from guardian and a reduce in power ,so none of which is makeing sense ,but anyway the just is Now my therm problem is fixed i guess cant tell a diff in engine profor, And Im being told I need a tps another 180 dollors plus 1/2 labor , I felt like im getting hosed So i go to another dealer he explain what Iv been though he hooks up ddt showing tps fault . before i spend more $$$$ my question is can a weak tps or going bad tps make me loose the top end, or any ideas The following have been checked 1. Compression check 90 psi all 2.Fuel pres check. Normal, 3. thermostats 4. spark plugs 5. coil packs 6. new fuel in tank 7. Batterey voltage 1000ca 8.injectors normal 9. Fuel rail no leakage 10. Fuel bulb staying firm 11. Air compressor normal. Please someone help me I just dont trust these boat dealers I understand they half to make money but Man its one thing after another . HELP

[EuropeanAM]

Sorry to hear of your misfortune!

Either (or both) the thermostat OR TPS problems could result in your complaints. For a little further details:

1. Thermoststats: You've been told correctly. If the engine had ACTUALLY had all the recommended updates, it would already have been equipped with 130 degree thermostats. Hopefully, when these were replaced, they were done with a "thermostat kit" (it's a little more cost effective, and includes the covers, 130 degree thermostats, and gaskets). And yes, a sticking (open) thermostat can prevent the engine from coming up to temperature, and results in "RICH" engine operation (potentially fouling spark plugs).

2. TPS: TPS failures can be "tricky". It's possible to have a TPS problem, and NOT receive any warning horn indication. The warning horn will ONLY sound if the TPS value falls "outside it's pre-programmed diagnostic parameters".

The TPS is simply a "variable resistor". The best way to describe it is to think of an older console TV... surely you remember one of these that had the old "dial type volume knob". Same principle! If you'll recall, they eventually became "worn", and had "dead spots" as you turned the volume knob. This is one possible failure mode on the TPS.... and unless you happen to land "on the dead spot" for approximately 6 seconds or more- there may be "no fault or warning horn".

I would recommend replacing the TPS, clearing the faults, and seeing how it does. You're likely NOT being "hosed" on this.

If you were here in Greenville, I'd be glad to actually "show" you how the TPS is functioning (or not) via a "printed graph sweep test".