Tbi on 4.3l boat

[jokey]

Hi guys I am new to the efi programing thing. I have a boat and installed the tbi system off an 86 caprice with 4.3l. I have the hole system set up and running but I need to tune it. It idles to high when cold and when I run it for a while the motor runs to rich. The ecm I am using is 1227137 with $27 code. I would like to fix these issues. I have to disable closed loop, egr, and adjust the idle.

Is there a way to run the 1227727 ecm with tbi? I would love to use this ecm because it is weather proof.

Plus I need help on which programs to use for tuning and buring the chip. I have intronics pocket programmer with rev2a rom emulator

[EagleMark]

Most of the tuners around here use TunerPro V5

High idle when cold is normal on cars but can be a nusince in boats do to normally warmer weather. Need to check your thermastat to and make sure it gets high enough to make the ECM think it's warmed up. Boats are usually 160 and cars 180 to 190. Otherwise a high idle ususlly is a vacuum leak.

There's a lot of GM EFI systems out there that run open loop. May be better to just get a marine .bin file. As soon as you turn your ignition on the MAP takes a reading for elevation. But after that your running on maps with no O2 feedback. I've gotten them dailed in faily easy on a boat because it's always working hard. Find your motor top RPM and get the prop matched. TunerPro and a cable will record the data you need to adjust. HTH!

:welcome2:

[dave w]

I've only modified V6 Memcals to be used in a V8. I don't know how to actually modify the '7727 Memcal for TBI.
Maybe jwscab over at Thridgen.org can make you a Memcal like the one pictured to run TBI? I purchased one of jwscab Memcals for a V8 conversion I did a couple years ago.


Here are the notes I have about modifying the 7727 PCM for TBI.

dave w

The number of cylinders is selected by the voltage on pin 11 on the 34984 (aka 79435) chip. This is U13 in a '7727, '7730, and '7749. The pin 11 voltage comes from pin 56 of the MEMCAL. This in turn connects to pin 13 of the 16 pin resistor network in the MEMCAL.

Here's how the voltages are interpreted:
0 to 1 volt : 8 cylinder port injection
1 to 2.5 volts : 6 cylinder port injection
2.5 to 4 volts : 4 cylinder port injection
4 to 5 volts : throttle body injection (any cylinder count)

The '727 I tested this on defaulted to "4 cylinder port" when pin 11 was not driven (no MEMCAL).



The CPU can read out the pin 11 mode selection. Code 41 will be flagged if it doesn't match the cylinder selection stored separately in the MEMCAL's EPROM

[EagleMark]

Got to be easier to start with a V6 weatherproof ECM. I do not know the ECM numbers on them but there are bizillions of them out there compared to finding one from a Corvette.

[jokey]

Well thanks for the info. I have downloaded tunerpro5 but I still dont know how to use it. Could some point me to a faq on it. Also does anyone know where to down load $27 definitions for the 1227137 ecm I am running.


I know there is tbi memcal for running a P4 ecm (16197427). But this version of ecm is not weather proof. I am not sure if the drivers in the 1227727 ecm will work with the tbi set up. Also I am not sure if all the inputs are addressed the same between the two.

[EagleMark]

Pretty sure the memcal is the same.

There's a 27.xdf in our library at
http://eagle-mark.com/pictures/albums/DEFS/_27.xdf" onclick="window.open(this.href);return false;
Click on it and it will open in a new window. Copy the complete page and paste into notepad and save as $27.xdf and you should be able to read and change the chip in TunerPro with that.

But I did not see an ADX file for it? (Aqusision data)

Check TunerPro page no one ever goes to and match up the vin letter or motor to a file.
http://tunerpro.net/gmOBDI.htm

[dave w]

Got to be easier to start with a V6 weatherproof ECM. I do not know the ECM numbers on them but there are bizillions of them out there compared to finding one from a Corvette.

Most all '7727 were port fuel injection V6 and V8. Of the bizillions of '7727 out there, only a few hundred were TBI. The homemade memcal I posted a picture of is set up for port injection V8. I'm sure the homemade memcal could be set up for TBI. I'm sure it's also possible to modify a V6 memcal to TBI, I just don't know how to modify the V6 memcal for a TBI conversion. The '7727 V6 to V8 memcal conversion is all I ever done.

dave w

[1project2many]

If you get to a point where you need it, I have at least one TBI cal for a 7730 which I would forward.

[EagleMark]

I have an upcoming project that could use that if you don't mind sharing. Don't forget we do have a library for these to collect as well. I think I still have 40 or so to add that I have been collecting. If there's something your needing you don't see there I will look to see if I have not uploaded it yet.