5.7 Dies when pulled to idle

[05rinkerclay]

'05 Rinker, 21 ft, wakeboard boat. I built a new 5.7 block and moved all the accessories from the original 5.0. Computer controlled and fuel injected. I had the ECM remapped by whipple to run the new engine stronger at altitude in Utah. Also stock rebuilt the lower unit (Alpha I). She runs great. Starts right up, idles fine and has power to get on plane, which was the problem that drove the change. But when under power, if I pull the throttle to idle, it dies. Starts again at the turn of the key. if I leave it in neutral and rev the engine, then cut to idle, no problem, no shutdown. But under load, pull the throttle, she dies every time. if I retard the throttle slowly, she keeps running. I'm trying to figure this out and hoping someone out there understands these components and issues...something to do with the prop still turning when the engine wants to slow...ECM not mapped right to provide the right fuel as it slows? any help is appreciated.

 

[alldodge]

ECM not mapped right to provide the right fuel as it slows?

I would say this is the most likely spot.
Whipple does many things but have not been a fan of their tuning, but many others like them.

Need to have a scanner placed on the motor to see what are the IAC counts at idle. If its more then 40 then it doesn't have much to work with

Would also like to know what they changed in the injector pulse width, might have it to lean

 

[Rick Stephens]

Any possibility a sticky lower shift cable?

 

[alldodge]

Any possibility a sticky lower shift cable?

Very good point :thumb: along with shift interrupter

 

[DGorvetzian]

Very good point :thumb: along with shift interrupter

+1 on shift interrupter (presuming that's the little gizmo that momentarily cuts the engine as you're shifting to neutral, so that the gears disengage smoothly). I didn't know about that damn contraption and suffered with my 4.3LX Mercruiser regularly dying when shifting to neutral. My shift cable had crimped a bit and was causing drag on the shift cable, so the shift interrupter was hanging out for too long in the 'cut power to the coil' position. Sometimes it hung out there and prevented me from re-starting the engine. Couldn't start it for 5, 10, 15 minutes, then all of the sudden, it just fired up. That problem made me crazy.

I found a vague reference in the Alpha One outdrive installation manual to be careful when installing the outdrive because there was a risk of crimping the cable. Go figure. I pulled the outdrive, replaced the cable, and never had the problem again.