Help? "Limp Home" mode kicking in for no reason... Not sure where to start?

[SoldTheBayliner]

Fantastic. I can work with that. I know where the Temp gauge sensor is... haven't looked for the other stuff obviously..... Thanks a million. I'll start with the oil pressure switch... That gauge has been rock solid and it doesn't leak a drop... I'm pretty confident oil pressure is fine. So that obviously only detects pressure... the SLOW kicking on when I'm banking through a turn or with the nose in the air not on a plane is just random coincidence... I really thought I was on to something there. haha.

I'll post results after I get it on the water.....

[SoldTheBayliner]

OK for future searchers.... on the mighty Apex, the temp switch is kind of right below/behind the thermostat housing (behind being on the front of the motor, rear of the boat). My finger is touching it in this pic... tan wire. Green wire has to be the gauge sensor.
I have a question on this: The pin that the wire attaches to is kind of wiggly in there.. is that just an insulation thing because it's a temperature sensor, or could this looseness be my problem? The wire is attached firmly, threads are tight, but the actual pin that goes through the switch itself has some jiggle to it.
Also, there's a lot of wire there for both the gauge sensor and the switch.. could that be touching something and getting hot and tripping the system?




the oil pressure switch is on the starboard (driver's side) of the boat, near the rear of the engine, so towards the front of the boat, kind of tucked behind the motor for the optional shower... which serves no purpose by the way, other than to be in the way, and one more thing to winterize. haha.... The oil pressure unit for the gauge is a big sucker. Mine is black. Oil pressure switch has a green wire.








EDIT EDIT EDIT = = = = === === = = = = == = = = == = = = =

Trial and error proved that I was wrong about the temp switch gauge and switch for the SLOW system... The switch is the GREEN wire, not the one I'm touching in the pic. The tan one (below the t-stat housing) is the gauge sending unit.

[SoldTheBayliner]

OK baffling update... help a brother out... I'm completely stumped again.

Took it out today. I had topped off the engine oil, so I was hoping that maybe it was legit low oil pressure tripping the switch. So I left both the switches plugged in and went out and ran it. It ran like a top at faster speeds, like it has been... slowed it down for a little kid tube run, and boom it cut out again. This happened a couple times. So knowing what I know now from this thread, I disconnected both of the wires at the switches on the engine....

Took off for a slow little kid tube run... all good for maybe 2 minutes... then boom, limp mode kicks in again. How in the world?? And then I noticed that the temp gauge was reading zero. Oooohhhhhh! I had the switch and the gauge sending unit mixed up on the temperature side of things (see my edit in my last post... makes sense, both of the switches are green wires and the gauge sending units are tan wires). So I hooked the tan wire back up (gauge springs to life), and disconnected the green one for the SLOW switch. So now I have both switches disconnected for sure, no way it can kick back on...right? Wrong.

Set off again for a slow tube run (we're talking like surfing speeds... maybe 10 mph, 2000 RPMs) and boom, limp mode kicks on.

Temperature is sitting at 165/170, oil pressure is perfect at 40, engine feels and sounds like its running perfect, and neither of the switches connected that could trip the SLOW system to come on... and it comes on. If you run it at "normal" speeds for wakeboarding or cruising around, it runs perfect with no issues and the SLOW mode doesn't come on. 3 minutes in to a slower run and it comes on. I confirmed this with no tube behind the boat, and I watched both gauges (temp and oil) indicating perfect levels when it kicked on. Plugged in to a computer at the boat shop, it's not throwing any codes.

What can I look at next? I'm $500 in to this problem and the shop is clueless. On the frustration scale, with 1 being Hawaii vacation and 10 being "push the boat off of a cliff," I'm at like a 6.8.....

NautiqueJeff is there a way to disable it at "Pin 24" at the ECA? Or is the ECA now a suspected problem? I'm hoping this didn't just get really expensive...

[NautiqueJeff]

Wow! I am stumped on this one.

Just to be sure, the check engine light is coming on when this problem occurs, correct?

The ONLY thing I can think of is that maybe there is something different about the Apex engine. I have little experience with that particular engine, but everything I have read says that those are the only two things that should trip the SLOW system.

I wonder if one of the wires running to the switches might possibly be shorted somewhere on its path.

I will check with PCM on this, but it will probably be Monday before I get a response.

[NautiqueJeff]

I just e-mailed PCM. I'll let you know what they say.

[SoldTheBayliner]

It's crazy, right?
Thank you for contacting them... super curious obviously to hear what they way. Your post earlier said that those two wires run together and then to the ECA through one wire.... I'm going to track down that union and see if there's an issue there.... I thought of a short, but everything is in conduit that I can see. I'll dig around.

Honestly I haven't paid great attention to the check engine light. I think it is coming on yes... are you asking that just to verify that it is indeed the SLOW system and not something else that I'm experiencing?
The reason I'm confident that it is the SLOW system kicking on is that I have had it actually work like it's supposed to when I was overheating due to a blown up impeller. It's a pretty distinctive feel... you can tell it's instant firing order gibberish and RPM limit, as opposed to a loss of power. But I can't say for sure that I've noticed the check engine light. I think it's coming on. But I look up and smack myself in the forehead when it happens so I can't be certain. haha.

The only other thing I've messed with is the fuel filter. I am still running on a very old filter, new one arrives Monday. I have taken the fuel filter canister off and pulled it all apart hoping the new filter would come before today, but it didn't so I put it back together with the old filter in there. Don't see how that could affect anything, but if there's a fuel pressure connection somehow, that should be back at 100% with the new filter. It seems like if that was the problem it would show itself at higher RPMs when you were asking for more fuel though...

[NautiqueJeff]

I heard back from PCM today. They said that those two switches are indeed the only thing that would be activating limp mode. With the switches disconnected, it certainly shouldn't be going into limp mode. Are you sure you disconnected the switches, and not the sensors for the gauges?

We need to determine if the check engine light is coming on. If it isn't, then it probably isn't SLOW/limp mode kicking in.

[nyryan2001]

Does this engine have ignition coils?

[SoldTheBayliner]

It does not have individual coil packs at each cylinder, if that’s what you mean...


Jeff, thanks for the follow-up... I am certain I (eventually) disconnected both switches. The oil one is unmistakable because the gauge sending unit looks like a giant acorn and there’s only one other thing there. The temp one looks just like the gauge sending unit but I killed the gauge first and then disconnected the switch. Tucked both wires into their rubber boots at the end so they couldn’t short on anything.

Ill go go out this week and confirm the check engine light. It is certainly feeling exactly like the SLOW system is kicking on... messed up firing order and an rpm limit... exactly like what it did once upon a time when I actually was overheating (impeller) and the SLOW system kicked on. Same exact thing.

[Peter6000]

As earlier stated the only condition that would cause SLOW is the oil pressure or overheating. Also the Check engine light should turn on.
The Check engine light should also be on if Ignition is on and engine off.

The engine has another mode that switches the ECU if a sensor fails. The reaction depends on the failing sensor.
In any case the Idle RPM should move from 600 to 800 when this happens.

So 3 questions, does the check engine come on? does idle RPM go up be 200 when it happens? does your engine have distributer?

If SLOW is happening the ECU cuts fuel to the injectors by cutting the pulse width to the injectors this actually hard to measure but would be a good way to prove that it actually is in SLOW. You would need a Multimeter that can measure pulse-width.

Another idea: When you on the water, both sensors disconnected and the problem is happening,
short one of the sensors to ground this will put the engine in SLOW for sure.
-If you already in SLOW there should be no change in performance
-If there is a additional change in performance SLOW is not your problem

I would do some additional testing on your next trip.
-Bring a voltmeter and connect it to ground and Pin 24 on the ecu as close as you can get to the ecu or put it one of the disconnected sensors.
You should see something between 5 and 12 V if it goes to 0 this is the cause of your SLOW
-Measure fuel pressure should be at least 28psi compare normal operation to problem condition.
-bring a strobe light if you have and check ignition timing compare normal operation to problem condition.

BTW: I have a Ford Rotunda breakout box and a Innova code reader that works on these engines (60 pin connector ECU's)
I converted to my engine to a MS3 aftermarket fuel injection and don't need them anymore.

Peter

[SoldTheBayliner]

Huh. Stuff to look at, thanks. I don't have a voltmeter or a timing strobe.... but I can check by grounding out the switch wires. I will also double check to make sure one of the wires didn't peek out of it's boot and ground out while disconnected. I wasn't as careful about that as I could have been.

Distributor - yes it has a distributor (car guy here... if the thing that looks like a distributor cap with wires running to the spark plugs is also a distributor cap in a boat, then yes. Haha.

Idle RPM... have not checked. I will pay attention to that next time out. I'm always around 2k when it happens, and I just back off and kill the motor, start it back up and it's fine for another 3 minutes at 2k RPM's, and then it happens again. More gas and boat up on a plane, and it never happens. I never back off when it happens and just sit there idling. Would the idle be at 800 even while not experiencing this issue? Like until you fix the faulty sensor somewhere, boat always idles at 800?


HOLY SMOKES!! As I typed that last paragraph that a light bulb went off and I went back and read that thing Jeff posted about the SLOW mode on page 1 of this thread. It says "below 2700 RPMs the engine will run normally, but not above." That is 100% NOT the case for me... firing order is all jacked up well below 2000 RPMs. Additionally, it doesn't kick on in the 3k RPM range, it only goes into this mode at slower engine and boat speeds... guessing 2500 would be about the highest RPM I've had it happen. You can go wakeboard all day and it won't happen, but 2 minutes into a surf run you'd smack into the back of the boat when it decided to run funny. Does that completely rule out SLOW, or is it possible that RPM thing might not be the case in this boat? I want to say that *maybe* once, I had it go "back to normal" without shutting the boat off... I think I pulled it back to an idle and was trying to get a feel for what was happening and it sort of reset itself with the boat running...once... but I am usually quick to just shut it off. I could play with that a little bit next time out to confirm....

What the heck might that mean? I was leading up to this question anyway, pretty confident on my end that it is still the SLOW mode kicking on even though that's impossible.... but this makes it even more relevant: If it's not SLOW mode, what could it be? It is obviously an instant change in firing order, not a "loss of power." It is the same feeling at the driver's seat that I have experienced when overheating and SLOW kicked on. What else can make it run like the distributor is having a seizure... and then instantly fix itself when you shut it off and fire it back up?


My new fuel filter should get here today, so I'll throw that in before I take it out again.....

[Peter6000]

Considering that your shop was unable to fix it you may need to invest in some test equipment.
First you need to find out what actually happens and determine if it is a fuel problem, a ignition problem or SLOW activation.
To me it sounds more like ignition I would attack in the following order.

-check and clean all connectors (use contact cleaner) specially the ones on the TFI and Ign coil
-Attach a fuel pressure meter and leave it on (easy to do) and keep an eye on it. Make sure its not leaking.
-attache a strobe light and since this is at 2000 RPM bring a 2nd person to actually do test.
compare timing advance normal run to problem
-attach a ignition power meter between spark output from coil to distributor don't touch it when the engine is running.
look for changes when the problem starts

if all of this looks normal
check the voltage on the following sensors
-Throttle Position Sensor (TPS) (engine off Ign on) should be 0-5V from Idle position to full Throttle go slow there should be no drops
-Coolant temp Sensor (ECT) around 1V at operation temp 2.5V cold engine (80deg F)
-Air Temp Sensor (ACT) around 1V at operation temp 2.5V cold engine (80deg F)

If you need a ProBoss manual download it from here: https://www.planetnautique.com/Corre...e%20Manual.pdf

Cheap test equipment, I do not recommend harbor freight for good quality but it is cheap:
Multimeter with pulse width https://www.harborfreight.com/5-in-1...ter-98674.html
Strobe https://www.harborfreight.com/timing...nce-40963.html
Ignition power tester https://www.harborfreight.com/90-in-...ker-63593.html
Fuel pressure Tester https://www.harborfreight.com/fuel-i...ter-62623.html

Take some pictures of the engine specially around the distributor and ign. coil to find out what kind of TFI module your engine uses.

Looks like you have a good day of work ahead of you. I would leave the engine cover at home for easy access. An hope its not the computer itself.

Peter

[SoldTheBayliner]

^^ That manual is for the GT-40, this is the APEX. Got a link for that one?

[nyryan2001]

You guys saying overheat and oil pressure are the only two causes for limp... you don’t know that. All you know is those two definitely DO cause limp. There could be other issues related to the ECU that were not spelled out in that diagram that shows oil pressure and heat force a limp mode.

I Continue to believe it’s an ignition problem...whether cap and rotor, firing order, or something with the knock sensor.

I just saw this... exact same behavior as he describes. It was an ignition problem failing to ignite causing knock and then engine into limp mode.

[Peter6000]

I don't have anything for the APEX version, does it use the same Ford ECU then the GT40?, If so oil and water or a defective ECU would be the only cause of SLOW mode.
I also believe this is a ignition issue.
Some pictures would really help to find out whats installed.
Peter