1 MAIDEN AMERICA

2002 575SCi. Ran great. Pulled out of the lake (1300ft) to go elsewhere and found a crack in the prop (Labbed 32 Maximus). Two days later it was repaired and I was back in the same lake. Now it runs badly (rich).
Engine warm and idling:
IAC=30
base IAC=30
IAC follower=0
TPS=.49V
MAP=13.9hg and appx 2V, cold it was [email protected]
injector on time=2.6ms
fuel flow=3.5GPH
IAT=90
coolant temp=164
Fuel pressure=28PSI
Vacuum=5" and steady
Compared to the good running engine the specs are the same except:
Injector on time=2.1ms
Fuel flow=2.8GPH
MAP [email protected]
All the plugs are black (equally). I changed them, and the cap and rotor. Snagged the MAP and coil from the other engine which runs fine, same problem.
The scan tool said "general warning #1 telltale indicator has been set". What does that mean?
Cleared code, same problem. Code has not come back.
I grounded one plug wire at a time. They all had the same effect.
No fuel in pump sight tube or regulator hose (PR will hold vacuum).
No H2O in oil.
Engine appears to smooth out at 3000+RPM, no load.
Engine does not spit out intake or exhaust.
If I unplug an injector it smooths out for a bit.
IAC's are clean, injectors all ohm the same (8 of them).
This is what I know.

Please help.
Thanks, Rob

mats

I am not familiar with the 575 SC but TPS 4.9V at idle?

hellbents10

You have a TPS problem 4.9v should be WOT, idle should be around .69v max.

Dave_N

Agree about the TPS being suspect. Both engines are showing 4.9 volts at idle? The attached image is from the Merc 575SCi diagnostic manual.

A general warning #1 telltale set means at some point the computer saw a low drive lube reservoir. Telltales will remain set until you clear all codes.

Dave

1 MAIDEN AMERICA

Had decimal in the wrong spot. .49V is actual. Thanks for the drive oil info. I've never seen low oil. Maybe I turned the key on with the drives empty or wires unplugged. It hasn't come back so far. I'm swapping ECU's tomorrow. Fingers are crossed.
Rob

mats

Some thoughts; The rich engine shows an 8% higher MAP reading with the corresponding 25% higher injector opening times and GPH. Was the opening time and the GPH value for the rich engine related to the MAP value when cold?

What was the MAP readings of the two engines with ignition on engine off? They should be the same on the two engines.

hellbents10

ECT sensor could be a problem too. That would be why its commanding a high duty cycle on the injectors. The higher map reading is due to it running less then optimal and or rich.

Turbojack

Had friend with cracked prop. I had repaired then shortly later had to idle back in on the other engine, buy a new prop and replaced the bent prop shaft. Better replace prop

1 MAIDEN AMERICA

MAP's are the same engine off.
ECT reads temps from cold to hot.
Switched ECM. No change.
If I unplug an injector while running (1500RPM) engine speeds up and smoothes out for a bit then dies off.
When I do the same on the good engine it dies off instantly.
I put my finger in the fuel spray path on the front injector of the bad engine. I feel more pulsation than the same injector on the good engine (more flow?).
I swapped injectors (#'s matched). Nice to have twins.
When starting the bad engine it popped back through the intake. Probably the fuel spilt swaping injectors.
It seems to run slightly better? Or am I getting used to it that way? Maybe just slightly on both accounts.
BAD discovery though. Looking at the rotors (again) I see the scuffs. They are on one side of each rotor, toward the center as if they ARE bent. The first time I looked at the rotors I didn't rotate them. They looked fine. This time I did. One side is good, the other has hit.
Could this be my problem?
Or did this just happen when the engine spit back?
Gonna yank both blowers tomorrow and go through them. Did I say "nice to have twins"?
I have the dipstick up front and oil reservoir in the rear style blowers. Changed oil every 25 hours at most. 188 hours total.
Will I have a hard time getting rotors/case?
I hope the intercooler caught some of the debris. Hopefully there isn't much to start with. The rotors appear more galled/smeared than pieces missing. If they hit the edge of the case though it could be a different story.
What's a little aluminum through the valves and cylinders?
I am going to junk that prop. (#5)
Thinking of standard IMCO lowers and 32 Hydros. See post in Fountain under "38 lightning, What to do?"
Thanks. I'll keep you posted. Rob

1 MAIDEN AMERICA

Rotors did not hit case. Bearings are good. Gears are good. Gonna see if they're bent tomorrow.
From "rich overnight" to poor. 3, 5 and 7 have no compression. Cylinders are good, not the gaskets though.
Rob