First boat, need help 7.4 mpi rev limit issue

I

Iaintslow

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Jul 16, 2018
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Hello, i just got my first boat about 2 months ago and been trying to fix rpm issue ever since. Its a 2001 maxum with a single 7.4mpi L29 mefi3 engine. It in some sort if guardian mode and won't pass 3k rpm in drive or neutral, in neutral it will go to 3.2k and bounce off like its a redline. I have no engine codes. I did full tune up including ignition module ,coil, fuel filters, map air temp and coolant sensors. Checked base timing which is arnd 8-9deg and it is advancing as far as i can tell. Checked knock sensors,tps, oil pressure switch, fuel pressure is at 36psi idle and 42psi under load, i really don't know what else it could be besides ecm?? Boat beeps twice abt 1 sec each beep when i turn the key on. Manual says beep for 2 sec and says nothing about 2 beeps so im not sure if its normal or not. All fluids are full and i have no alarms. Sometimes when i have a lot of people on the boat it wont pass 2.4k rpm since it can't get on the plane, its like running on 50% power
 
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tpenfield

tpenfield

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:welcome:

What did you use to check for engine codes? Something would have to be wrong for it to go into guardian mode, so I would expect some sort of code . . .
 
A

AlabamaNewbie

Petty Officer 1st Class
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Jun 25, 2018
Messages
239
If you are using an aftermarket code reader like you'd get at a parts store - it may not be able to read the codes. There are about 7 different programming languages that are used, for some reason people couldn't get together and standardize it. Those inexpensive aftermarket readers will claim that they can read all code languages, but they have to be able to read the version of the language as well.

Just saying that because if you are relying on one of those to pull codes, it may just not be able to interpret the data string its receiving.
 
I

Iaintslow

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Jul 16, 2018
Messages
16
tpenfield said:
:welcome:

What did you use to check for engine codes? Something would have to be wrong for it to go into guardian mode, so I would expect some sort of code . . .
Click to expand...

I don't have the reader, I used a jumper and led light, i only get code 12 which is nothing
 
jbcurt00

jbcurt00

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mysticCrunch said:
...... HELP Don't want to mess up 7.4 mag with only 60 hrs on it HELP!!!!
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Mystic, please start a topic about your 7.4Mag and its problem. Asking here in another members topic is considered a hijack.
 
achris

achris

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May 19, 2004
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mysticCrunch said:
I have the same problem and I want to solve it .
Click to expand...

No, you have a similar symptom. The solution may be completely different. Please don't hijack someone else's thread, start your own.

Chris.
iboats mod team.
 
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achris

achris

More fish than mountain goat
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27,468
Iaintslow said:
I don't have the reader, I used a jumper and led light, i only get code 12 which is nothing
Click to expand...

You may have an IAC problem, but without a proper code reader, like the Scantool or the laptop based Diacom software, we're guessing in the dark.

Chris. ....
 
GA_Boater

GA_Boater

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Since some people think they own the forum and rules are meant for others, a few posts have been unapproved.

Meaning we will run the forum as WE SEE FIT! Got it, mysticCrunch ?

Sorry for the diversion, Iaintslow.
 
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