Old problem 2007 497 HO Mag Limp mode

[nasdaqsam]

I have posted on this issue in the past but the boat is out of storage now and we have tried, I believe, everything advised to date. Here is what I have. Engine Serial # OW652707 153 hours. Last year it would run ok until I started hitting the throttle then it would hit limp mode. Originally it would show different sensors being bad. The IAC has been changed it made no difference. Not knowing what was wrong I sent the ECM to Whipple for testing. It tested ok.

My mechanic has a newer much better testing computer now so figured this would be easy to fix but it's not. Here is what we have now. It is showing the IAC as being bad again but he has put a new in it again still shows as bad. But only shows bad when the engine is running. If you shut it off the code goes away. All the sensors test out according to the tests. All the connections have been checked and cleaned multiple times now. At this point we do not know where to turn or what to check next. Everything seems to point to the ECM being bad but at 2k a pop that is an expensive test because once plugged in I own it if it is not the problem.

Any thoughts/idea are GREATLY appreciated!!

EDIT, Also ran a secondary ground to the computer as advised by Whipple it made no difference.

 

[alldodge]

Check your voltages on the IAC with it running and not and see if there is any difference
Should also check the 5V circuits on the sensors (run and not running)

 

[muc]

What software is he using?

what happens when he uses the software to control the IAC? Does it set a fault then? Test both Running and key on.

what % of guardian shows on the computer when the fault is happening?

what are the fault seconds and at what RPM does the fault happen?

What codes are Showing?

 

[QBhoy]

Hi

very unlikely the iac is putting it in guardian mode. It didn’t on mine I’m sure. Just beeped every few seconds. Not sure it was in guardian mode when it happened to me. If it did it would be to 90% power at worst.
Some of the guys on here have info on exactly what faults determine what level of guardian mode it goes into. There are a few different scenarios and resulting modes.
Without knowing your exact situation, I’d take a guess at one of the more intervening causes of guardian mode like the SW pressure switch.

 

[nasdaqsam]

Check your voltages on the IAC with it running and not and see if there is any difference
Should also check the 5V circuits on the sensors (run and not running)

Ok will do and will get back to you. Thanks

 

[nasdaqsam]

What software is he using?

what happens when he uses the software to control the IAC? Does it set a fault then? Test both Running and key on.

what % of guardian shows on the computer when the fault is happening?

what are the fault seconds and at what RPM does the fault happen?

What codes are Showing?

I will get some answers to these and get back. Thanks

 

[nasdaqsam]

Hi

very unlikely the iac is putting it in guardian mode. It didn’t on mine I’m sure. Just beeped every few seconds. Not sure it was in guardian mode when it happened to me. If it did it would be to 90% power at worst.
Some of the guys on here have info on exactly what faults determine what level of guardian mode it goes into. There are a few different scenarios and resulting modes.
Without knowing your exact situation, I’d take a guess at one of the more intervening causes of guardian mode like the SW pressure switch.

When it goes into guardian at least the last time I ran it on the water it hits guardian just above idle maybe 2000rpms but that's a guess. It will not go over 10mph when in guardian this is a 60mph boat so I am getting maybe 10% to 15% power. Two beeps no power. What is the SW pressure switch?

 

[nasdaqsam]

Few answers and some info. The software is diesel laptops he didn't have the version. When he runs it not under load he is hitting the guardian at around 2500rpms. He didn't have some of the info but will get it for me.

One things he said is he is getting no reading out of the IAC. It will run with no reading/power and when not running key on there is no reading/power coming out. He thought broken wire possibly but he is saying the harness is in like new condition. Keep in mind this boat has 153 hours on it. It spent the better part of its life in a temp controlled showroom. The rest was always covered or on a covered boat hoist. It gets stored indoors during the winter. There is zero sign of rodent damage like chewing wires etc. Does any of this help?

 

[QBhoy]

When it goes into guardian at least the last time I ran it on the water it hits guardian just above idle maybe 2000rpms but that's a guess. It will not go over 10mph when in guardian this is a 60mph boat so I am getting maybe 10% to 15% power. Two beeps no power. What is the SW pressure switch?

It’s one of the few alarms that will give a full on guardian mode.
Sounds like it’s in that state. Only a few like this and oil pressure will limit as much.

 

[alldodge]

Where missing a lot, and may have more if the original thread was used.
We are guessing because I was thinking the seawater (SW) pressure switch was changed. If the SW was not changed or tested, then that would cause the issue like Q mentioned.

The software is diesel laptops he didn't have the version.

What does diesel software have to do with this motor?

 

[nasdaqsam]

Where missing a lot, and may have more if the original thread was used.
We are guessing because I was thinking the seawater (SW) pressure switch was changed. If the SW was not changed or tested, then that would cause the issue like Q mentioned.



What does diesel software have to do with this motor?

This is the software he is using to test the sensors etc. Can the SW be tested? Or is it just a swap out part?

Edit, I know what you are saying about the original thread but there was not a lot of info in it as the boat was in storage when I was asking the questions so could not test anything.

Thanks again

 

[nasdaqsam]

It’s one of the few alarms that will give a full on guardian mode.
Sounds like it’s in that state. Only a few like this and oil pressure will limit as much.

Ok, we can swap it out. Definitely cheaper than new ECM or wiring harness. Thanks

 

[nasdaqsam]

What are the thoughts on no power/reading from the IAC when running or when off but key on? Is this suppose to be like this? Could the SW be the cause of this?

 

[QBhoy]

What are the thoughts on no power/reading from the IAC when running or when off but key on? Is this suppose to be like this? Could the SW be the cause of this?

Not sure without being there but I think you’re over thinking it in terms of the IAC. Can you manually try and choke the throttle body and see if the IAC reacts ?
youre engine is different from mine being bigger but if the same mpi dna i would imagine. I’m almost certain the IAC doesn’t have such a drastic effect in terms of guardian mode. Mine only beeped at me and didn’t notice a power drop really. The smart craft told me what it was just after.

AllDodge will surely have a list of what will cause a 90% guardian mode on your engine perhaps.

 

[nasdaqsam]

Not sure without being there but I think you’re over thinking it in terms of the IAC. Can you manually try and choke the throttle body and see if the IAC reacts ?
youre engine is different from mine being bigger but if the same mpi dna i would imagine. I’m almost certain the IAC doesn’t have such a drastic effect in terms of guardian mode. Mine only beeped at me and didn’t notice a power drop really. The smart craft told me what it was just after.

AllDodge will surely have a list of what will cause a 90% guardian mode on your engine perhaps.

My guy is going to get a reading on what percentage of guardian it is actually in. I could be over stating it as for a boat owner its more about it just isn't running why not so tend to over exaggerate things. Thanks for the help.

 

[QBhoy]

All that said. You should get a beep with a SW pressure fault. Could this be a fuel pump issue ?
presuming you mean it’s a 496 maybe ? Apologies. Not too up on the big blocks.

 

[nasdaqsam]

All that said. You should get a beep with a SW pressure fault. Could this be a fuel pump issue ?
presuming you mean it’s a 496 maybe ? Apologies. Not too up on the big blocks.

Yes its a 496 my bad. Big fingers small key board. lol. I get two beeps from memory about every 10 to 15 seconds.

 

[QBhoy]

Yes its a 496 my bad. Big fingers small key board. lol. I get two beeps from memory about every 10 to 15 seconds.

Ok. Then it’s likely one of the known common faults. Plenty of reading for you online. But I’d guess at a SW pressure sensor.
Don’t rule out the iac but I don’t think it would cause such dramatic loss in power.
Other culprit would be the throttle position sensor. Or TPS.
AC Chris is pretty good with these things too. He will likely chip in.

 

[nasdaqsam]

Ok. Then it’s likely one of the known common faults. Plenty of reading for you online. But I’d guess at a SW pressure sensor.
Don’t rule out the iac but I don’t think it would cause such dramatic loss in power.
Other culprit would be the throttle position sensor. Or TPS.
AC Chris is pretty good with these things too. He will likely chip in.

Lots of good minds on this forum they always been real helpful in the past for sure. Thanks

 

[nasdaqsam]

I have been emailing Whipple about the issue also since they tested the ECM. I get a response of "We must have tested" and "Maybe" for a response. These are not real confidence booster words. Did they actually spend anytime with it? Or just a quick test on their computer and it's good to go? I assumed they would do a thorough job. Guess not, basically I have no more confidence the ECM might be bad than I did before sending it in.