….. Speed density systems use TPS , Map , and RPM (speed) … have you confirmed an RPM signal to the Engine Control Unit ? …..

 

Up here they still run 175. Thermostat controlled.The water in the block just "stacks up" to get to temp... The heat exchanger is primarily used for sea-water, but more importantly, when you have aluminum heads/ iron block. This stops the electrolysis interaction between the 2 different metals. They still run 175 degrees temp...

As of now in the US, no emissions. But dam near anything built after 2010ish has 4 O2 sensors, and Cats. (2 pre cat O2s, 2 post cat O2s)....These will go into open/ closed loop.

CTS is in thermostat housing on most everything. But it can be in the head as well (depends the MFG)...A SBC engine longblock is the same. Its all the stuff they put on them that makes them different.

MAP 1 and 2 is just that - vac/boost....1 and 2 atmospheres....they read like any other. 5 volts in, up to 5 out. The problem is HOW you read it. KPA,PSI,Etc....It gets confusing sometimes. For example, Yamaha uses PSI. So at sea level, we are at 14.7 PSI. Less then that obviously is vacuum. Mercury uses In/hg...So 29.9 at sea level, Half that running.

Any "smart" engine wont just shut it right off. For the most part, they will gradually pull power away from engine, giving a code, and 'hopefully' you check it out. It all depends on the severity of the situation. Example, a CTS failure will tell the ECM to knock power to 90%, give a code, and use DEFAULT values if this happens. This way the weekend isnt ruined....Now if the engine starts overheating, youll go from 100% power to a shut down as the temp goes up (around 240ish). The ONLY thing besides a severe overheat is battery voltage. This is on battery driven systems. If the ECM receives less than 9.5 volts, it cant function...So it stops running....Most of this is to pull the customer out of the loop (I didnt overheat and blow up my motor- its warranty!!! ....Nope). Most of the ECMs remember the last 13 or so minutes of running...I can tell YOU what you did to it....

The reason everyone is confused looking at those numbers he posted is because, 1- Not all the categories listed have a function on that engine. And 2- with Marine engines, there are a few programs to read the info with. Not all translate well. Also, Marine engines have a totally different set of parameters they run on. Water PSI, in gear or not, water in fuel,etc...

And as far as NON-O2 goes, they use speed/density systems.. Only use engine temp, MAP, TPS.....If there is a crank sensor and it fails, usually you will have no spark, and no injectors. But for the most part electronics on these engines are pretty reliable. That being said, Indmars market is probably in the 10% range - if that. So you will see a hell of alot more Mercruisers and Volvo than anything. So the setups they use can be weird as hell sometimes...

And yes boats have a OBD port, but its Marine specific. And if that aint a bitch, companies can (and do) use there own harness and software. I have 6 programs, and about 20 harness i use. Thats why i laugh at how OBD,OBD2 works...Must be nice to have one scanner, lol....

 

Also as of now, anything over 500HP dosent need emissions,,This will change, but the MFGs are already setup for it...Go to Mercruiser racing and look at the 1400hp engine..O2s, Cats, emission friendly....

 

And also, he can have fuel PSI all day long. Not gonna change if injectors are clogged. The return loop on his engine goes back to the fuel pump. So that 'loop' will read ok. Need to watch the gauge as he revs it, puts in gear, and when it dies....

I need to know if he just bought it (someone gave up), or if it ran fine, sat a year, then acted up....Makes a big difference in trying to help.

 

One more thing... Cars go into closed loop when warmed up. But when you floor it, it goes to open loop. So boats run WOT all day - it would just stay in open anyways. But now they can adjust everything even up to WOT....

I know cars are different and there is alot of different systems, Boats are the same way. Depends n the MFG and what they used that year.

 

Huge thanks for all the info you guys are great.

Tell me if I am wrong because I am new to all this but I don’t see the engine running under load if the injector pulse width doesn’t go up when I run the throttle up.

the thermostat bypasses the water and all goes through the exhaust manifolds when the engine is cold.

Key on engine off map map voltage shows 1. 4 volts on software shouldn’t that be around 5?

 

You already replaced MAP right?
i need to know if you bought boat this way or if it ran fine then sat a year....Big help knowing this....
Also, what program are you using to read the ECM?

 

Yes new map ran exactly the same as the old map

yes it ran good

scanerpro

 

Take a look at the fuel lines like i was saying......Also what year is it, and what part of the country are you in? Have you had it since new?

Seeing how it was fine then sat a year, im still leaning towards fuel...ESPECIALLY that anti-syphon valve. Sensors dont usually go bad from sitting for a year - fuel does. Its cheap and easy to replace the lines and valve. Even if thats not the issue, youll save yourself from trouble down the road (or sea)...

 

Gasoline with ethanol is just plain bad. Does the boat get ethanol in the gasoline or are you in a place where they don't add ethanol? Down here they charge more for the plain old gasoline that with the expensive alcohol added to it.

Did the boat get stored with gasoline in it? I usually keep the fuel empty when I remove it for the season. I agree with FostersPerformance as I too am suspicious of your fuel system. Todays gasoline with ethanol has a short shelf life unless additives are put in first. I had a fuel supply line get plugged internally and that really woke me up to the issue. I would certainly flush the lines out before each season's usage.

On this engine what does the OBD connector look like? This sure makes me appreciate my old Mercruiser and its simplicity....

 

The fuel is junk no matter where you are. 30 days MAX untreated...Best thing is to use up what you put in (after stabilizing it). Your on the water as well, and guess what alcohol attracts?? Yup, water... I have many,many horror fuel stories. But everyone overlooks the fuel lines. Since the 90s they are supposed to be able to handle 10%, but no.....You need to replace any fuel lines built before 2008 (they are all date coded per USCG regs). And the valve at the tank.....Replace it. Also, i doubt he has one, but they used fiberglass fuel tanks for YEARS.The alcohol would clean them, then strip the styrene out of them, destroying everything else after that....Not pretty. NEVER buy a boat with a glass tank, or plan on changing it.

I use a fuel tester here where i need to. Even ethanol free fuel usually isnt. Youd be surprised, and pissed, at what your putting in your tank. The tool is cheap. Its a glass tube - put gas in, then water, shake and itll show % of alcohol. Sometimes even insurance companies will want me to give a sample.

And NEVER EVER run dri-gas. Its alcohol. Your making the problem worse. If the fuel phase separates, there is NOTHING thatll bring it back to being usable. Dont be fooled into thinking otherwise. Even if you distill the fuel to remove the alcohol, your left with something like 75 octane fuel. Not good. Drain it, and refill with new.

Like i said, fuel issues are the most common boat problem.

As far as his connector i couldnt tell you what one he has. I have too many connectors for these 'odd' engine setups. Not ******* it, but i said before Indmars market is very very small compared to the big guys.

 

Quintin - did you ever get this solved? I have a MasterCraft 205 1997 with an LT1 - behaving in a similar fashion to what you have described - what was the solution?
I'm also looking for the diagnostic tools that you used to connect to the ECM - can you share the resource please? I found the ScannerPro/TunerPro software - just need the cable setup that you utilized.
Thanks in advance.