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6.2 MPI Bravo Shifting Engine Cut Out

I

iaff284

Contributing Member
Hey All,

We have a new to us 2007 Four Winns 260H. When shifting from neutral to forward or reverse the engine will stumble or bug down momentarily when it shifts into gear. It is very similar to when an alpha shift interrupter works. The engine starts and runs fine and it does not do it when shifting back to neutral. I know it has the gear indicator on the shifter plate, does the ecm cut ignition when a gear change is detected? Our other boat with the 6.2 Bravo 3 did not do this. The engine and drive serial numbers are Engine 1A050714 and Drive 0W940461. Thanks in advance!
 
Bravo drives do not have a shift interrupt switch. The switch they do have is a the "shift event switch" which tells the ecm/pcm that it is in gear.

Sounds like your IAC may have an issue.
 
Thanks for the reply dockside......I think the IAC is working properly as it idles up on initial startup and then settles down to normal idle speed within a couple seconds. Just out of curiosity I started the engine and then unplugged the “shift event switch” to simulate the plunger being activated when it is shifted and the engine idle dropped like timing or fuel was pulled by the ecm. As soon as I plugged it back in it returned to normal So I have a feeling that switch does more than we think.
 
iaff284 said:
Thanks for the reply dockside......I think the IAC is working properly as it idles up on initial startup and then settles down to normal idle speed within a couple seconds. Just out of curiosity I started the engine and then unplugged the “shift event switch” to simulate the plunger being activated when it is shifted and the engine idle dropped like timing or fuel was pulled by the ecm. As soon as I plugged it back in it returned to normal So I have a feeling that switch does more than we think.
Click to expand...

That is why it is called a "shift event switch". It removes the neutral over rev and changes the timing curve when the drive is shifted into gear.... If the switch changes the engine speed when disconnected, there is a good change the switch is the wrong one. There are two different switches.
 
I will double check the switch but I am pretty confident it had the female plug end for the shift indicator. It appears the interuppter has a male plug end. If the indicator manipulets the rpm and especially the timing would it not make sense that the idle would be affected?
 
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