7747 tbi 5.7 into my boat

first off, thank you for all the great info. i was able to convert my 5.7 mercruiser to tbi this spring. it runs pretty well, definitely better than the quadrajet that came off. I pulled the ecu/harness/sensors out of a truck with a manual transmission. i do not have a vss or o2. i have not attempted to tune at all. I was just wondering if anyone has a tune available for the 7747 that eliminates the o2 and vss and optimizes for high rpm (3500+).

the symptoms i would like to get rid of are:

1. slight bog when rapidly going from idle to WOT.
2. seems to run out of top end about 4,000 under a load.

thanks!
jason

You can "Ground" the Park wire, which tells the computer the engine is in "PARK" all the time eliminating the need for a VSS.

You can set the closed loop coolant temperature to maximum to keep the engine in "Open Loop", which should eliminate the need for an O2 sensor.

dave w

This gets tricky because you will need a way to tune fueling. You would need to put it on an engine dyno, or be really good at reading plugs. What year truck?

Quote:

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Originally Posted by 96lt4c4

This gets tricky because you will need a way to tune fueling. You would need to put it on an engine dyno, or be really good at reading plugs. What year truck?

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You can get adapters for 02 sensors for some ehaust manifold/riser designs. Plan to use them when my L31 from my Express ends up in my boat with the 0411 running it.

the tbi setup came out of a 1989 1500 with a 5.7 and manual trans. would i still need to ground the park wire if the computer came from a manual trans truck?

The harness from a manual truck won't even have the Park wire and I don't believe the manual trans tune will look for it. I don't have any experience with boats, so i don't know if the manual tune is better than one for an automatic for your application.

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Originally Posted by Fast355

You can get adapters for 02 sensors for some ehaust manifold/riser designs. Plan to use them when my L31 from my Express ends up in my boat with the 0411 running it.

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I have seen those, don't remember them being around when I did mine years ago.

My new boat has a TBI 350 in it stock, will do 55 MPH, and pulls anything I want behind it. I am leaving it alone...LOL

Quote:

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Originally Posted by 96lt4c4

I have seen those, don't remember them being around when I did mine years ago.

My new boat has a TBI 350 in it stock, will do 55 MPH, and pulls anything I want behind it. I am leaving it alone...LOL

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I like your conversion. I did a conversion carb to TBI a couple of years ago (7747 ECM). I fabricated my own O2 adapter to install in one riser. I then tuned the engine with a wideband. When I was done, I installed a 3 wire NB O2. It really ran great and had improved fuel economy with the CL. I just installed the ECU in a weather box from an Audi I had here at the shop.