496HO problems looking for input.
 

hey peeps.. I have a NEW to me 2006 baja with twin 496HO's. I only boated on it this year maybe a max of 10 to 15 hours.. anyway, the last couple times out the starboard side motor was acting weird and now she goes into guardian at 3500 RPM. here is a little boating history, I take the boat out and when trying to get the boat onto plane the starboard motor RPM compare to the port side isn't the same at the level the throttles are at. once the boat is on plane and moving alone I have to drop the port side throttle to keep the RPMS the same, and once you get the throttles fully forward the RPM's are off by 500 to 600rpm LESS on the starboard side.. I will attach video's of my flushing the engine and you can hear a difference in tone even at idle.. what do you guys think is the cause? IAC sensor? camshaft sensor?

now back to the guardian problem. the past 2 times out I will be boating for 20 to 30 minutes and BAM the alarm goes off (running about 4K rpm).. I drop the throttles down and stop the boat and the alarm goes off. I try and bring the boat back on plane and once the starboard motor hits 3500 it goes off again. I had a good friend stop by with a scanner and we notice sea pump pressure was the cause. the sea pump was replaced before me purchasing the boat and when you watch the videos attach you can see the engine IS pushing water out the pipes normally. do you guys think it could be a bad water pressure sensor?

video from yesterday you can hear the different tones throttles were down and RPM on gauges showed the same RPM
port side
https://www.youtube.com/watch?v=oAdOTDNkWQM

Starboard side that alarms
https://www.youtube.com/watch?v=z4xnysg47EA


scan hours were 238 and 237 hours on the motors.. the boat has been a lake fresh water boat its whole life.

http://i41.photobucket.com/albums/e2...pszi8g45xw.jpg

how do you attach the scan document showing the ECM information on this site? i'll try and copy and paste it

8 GUARDIAN
--------------------------------------------------------------------
FF Baro Pressure 14.84 PSI
FF Battery Volts 14.03 VDC
FF Sea Pump Pressure 1.43 PSI
FF Boat Speed 3.00 #
FF Manifold Air Temp 111.20 °F
FF Coolant Temp 172.40 °F
FF Demand 47.72 %
FF Engine Speed 3301 RPM
FF Engine State Running
FF FPC Total 64.5 Counts
FF Frequency Count 23
FF Fuel Level 0.00 %
FF Gear Position In Gear
FF Lake Temp 431.60 °F
FF Engine Load 29.77 %
FF Main Pwr Relay Requests YES
FF Manifold Air Pressure 12.72 PSI
FF Oil Level 0.00 %
FF Port Tab Pos 0.00 %
FF Available Power 5 %
FF Run Time 238.43 hrs
FF Starboard Tab Pos 0.00 %
FF TPS Percent 47.72 %
FF Trim Position 6.93 %

1) I'd buy a scanner and keep it on the boat. It's the best $500 you will ever spend. www.rinda.com (I speak from experience. Having that scanner helps you find a $49 bad sensor 3 days before 4th of July when no one can help you for weeks.)
2) You need to scan/read water pressure across the RPM range (while running the boat). This is another reason why I like mechanical water pressure gauges.
3) I've posted about this quite a few times: I've seen more than a few Bajas which have a problem with the Tee fitting for the fresh water flush getting gummed up with debris in the check ball/spring that's IN that Tee fitting. The engines will flow fine at idle, but water flow is restricted at speed/higher RPMs. (You can find some more info here on the site.)

i'll order one but what do you think about the tone difference and RPM loss?

1) Take off both of your flame arrestors, (with the engines off) and make sure both of your throttles are adjusted to the butterflies evenly.
2) Use the scan tool to make sure your Throttle Position Sensors are evenly reading across the throttle positions on each motor. (Represented by percentages)
3) Are you certain your props are 100% evenly matched? You could swap your propellers and run the boat in opposite shifter positions to verify that RPM differences are not prop induced. (Bravo drives can be spun either direction.)
4) Crank and Cam sensors can cause them RPM loss issues.

sea pump pressure way to low for 3301 rpms at 1.43 psi. Pull it clean it out and or install a new one to see if that reading jumps way up. You can test the sensor itself and also can test the water pressure reading with a fabbed outdrive pressure tester / gauge to compare the scan tool readings with the pressure tester..

So with the scan results as posted from post # 2 --- there is one issue that stands out along with showing something per engine why its doing what it is plus possible another problem area.

I will add a scan tool is not going to fix your engine but possible can lead to the problem area. You have to know how to read the scan and decipher. Without doing so you are wasting your money buying the tool.

Anyone want to answer what the big problem is and anything else per scan read out from post # 2 ?

Lake temp

both engines had the same Lake Temp on the scans

Doesn't Lake Temp require an external puck/transducer?

I don't know. I was just searching the web about this and another boats thread popped up with his scans and it had the same temps. I cant find anything about it.

Used guys Used guys a bit of info ----------- water temp has nothing to do with anything unless you have the paddle wheel and temp sensor app installed. WITHOUT a working sensor it defaults to the highest default number Merc calibrated the PCM / ECM for. Hence for the way high water temp reading. Its meaningless in this app.

tried sending you a PM but your box is full

I'll play.

Frequency counts
FPC counts
Available power at 5%

FWIW. I had the same issues going on with my engine. 2005 merc 496 mag. After a long couple months of wasting time replacing sensors, coils, plugs etc. the issue was the paint from the inside of the cool fuel module clogged my fuel injectors. Have you updated your cool fuel modules and cleaned entire fuel system?

Fuel pressure problems does not send the engine in guardian mode. The scan shows for one guardian mode with available power of ??? So do you have a problem yes or no ? - if so --- now you have to find out what your problem(s) are and why your engine is in guardian mode ? So how do you do that ? Where do you start ? Anything else possible might be going on with those scan results ?

FWIW get some of guys thinking about what a scan tool is really for. Instead of buying a scan tool problems solved . Does not work that way and if no fault codes are showing for whatever app does not mean anything, you still can have a problem(s) and hopefully knowing how to understand and read a scam tool can help you pin point the problem area(s) Not trying to be a bad guy about but IMO really putting forth solid info and about possible whether a scan tool is really for you or not.

went down to the boat this morning to check wiring and connections on the boat.. when checking, the back plug wire near under the manifold, wasn't pressed down onto the spark plug. after this, I check the throttle opening on both and this motor and adjusted the cable. we took the boat and no alarms and no stumble and both RPMS are within about 200 or so. thank you all for the input.

Good news...
Next time you have the scanner, do the check of the Throttle Position Sensors. You may have some more adjusting to do.

will do, my friend is going to bring it down and we are going to go for a quick ride to data record the motors..

So both engines can reach MAX rpms with no problems ? curious as water pressure output was very low per scan results

YES.. I am also, I removed and reinstalled the wiring to the sensor. I will scan live the engine.