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Thread: Here we go again

  1. #1
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    Here we go again

    The odyssey starts again.


    I have a FJ40 with an '83 305 (cam and intake upgrades) mated to a late model 4L60 with a manual lockup kit (was carb'd). I added a TBI and with the help of Dave W and a couple different forums modded the 7747 computer and burned my own chips. Fast forward 5 years and I am building a 350 from a '90 Caprice to put in it. The engine is bone stock and came with a full vehicle harness and the matching computer (1228746). The chip does not have the bin code on it, instead has "5369" printed on top. I am going to open the box to see if I can find the code on the memcal, but even then there isn't much I can find about the bin's for this computer.


    I am trying to decide the best way forward. I don't really want to go through a two month tune process like last time, but I am not sure I can completely avoid it. I don't see much on the $61 computer which makes me think I should avoid it and use the 7747. I do need to remove the trans and smog settings at a minimum. I read something about a possible power steering pressure sensor, but I am not sure if it had that yet. I don't mind keeping the EGR although my present harness doesn't have it.


    I am just looking for advice at the moment. Worth modding the 8746 for a 27SF512 chip and use the car engine harness or keep the 7747 and correct the harness to match sensor locations then find a decent starting bin?




    Thanks all!

  2. #2
    Fuel Injected!
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    https://www.thirdgen.org/forums/dfi-...vs-8746-a.html

    If it's true the hardware is the same maybe the pinouts are also so you can modify the caprice bin with your current tuning as a starting point.

  3. #3
    Super Moderator dave w's Avatar
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    There is a chance you have a Police Caprice 350 TBI engine? It might be a good idea to keep the original ECM and original .bin file if you find out you have the Police Caprice 350 TBI engine. Check the injectors in the TBI, maybe you have the lucky numbers 17084327?

    dave w

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    If you can get the scanID, one of the items available in the datastream, then I may be able to identify the calibration.

    You say you are building a 350, but what does that mean? Rebuilding to stock, or are you changing cam, pistons, heads, etc? Changes to airflow require changes to tuning.

    The older C3 ecms like the 8746 and 7747 contain most of the program to run the computer on a different chip than the eprom with the tuning data. The programs are different between the two computers so you cannot directly install a 7747 $42 calibration in an 8746 ecm and have it work properly.

    With your experience from the last time the tuning process might not take so long.

  5. #5
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    Dave, nice to see you here still. Thanks again for all your help on my 305 chip burns. It has run great for years.

    This engine was advertised as a 9C1 police engine, but it doesn't appear to be as it has swirl port heads, not the fast burns listed as being on the 9C1 engines. It was a B-body VIN so Caprice 4 door. I have yet to clean up the intake or rebuild the TBI. That will come soon.

    I took the board from the ECU today, no numbers. Looking at the top of the chip again I decided to cut one of the cross pieces off. Score!

    ANLU 5369.

    So now I am confused. This bin is listed as a the COP car bin. While the engine came with then green silicone hoses from a cop car, it didn't have an oil cooler. I need to get the codes from the injectors. I suppose I can mic the cam lobes too and see if it is the L98 cam or not.

    I need to do more research on this bin. It does not have VATS or a speed limiter (according to posts), but it does have the smog pump which needs to go.


    I don't mind a little learning curve on this ECU, but is there a point to it? Can I copy the same settings to a $42 bin? Is there a best, or easiest way forward with it?

    ---

    1project,

    I didn't trust the seller that it was a running engine so I tore it down. The bottom end looked nearly new so I am just putting it back together with new parts. The exhaust valve guides were over limit so I have a pair of rebuilt swirl ports for it. New rings, bearings, oil pump, etc. Roller lifters and cam are good so will go right back in.


    Quote Originally Posted by dave w View Post
    There is a chance you have a Police Caprice 350 TBI engine? It might be a good idea to keep the original ECM and original .bin file if you find out you have the Police Caprice 350 TBI engine. Check the injectors in the TBI, maybe you have the lucky numbers 17084327?

    dave w


    *****
    If you can get the scanID, one of the items available in the datastream, then I may be able to identify the calibration.


    You say you are building a 350, but what does that mean? Rebuilding to stock, or are you changing cam, pistons, heads, etc? Changes to airflow require changes to tuning.


    The older C3 ecms like the 8746 and 7747 contain most of the program to run the computer on a different chip than the eprom with the tuning data. The programs are different between the two computers so you cannot directly install a 7747 $42 calibration in an 8746 ecm and have it work properly.


    With your experience from the last time the tuning process might not take so long.

  6. #6
    Super Moderator dave w's Avatar
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    Here is the gearhead link to the '8746 information: http://www.gearhead-efi.com/Fuel-Inj...Information-61

    I like that the '8746 uses a Manifold Air Temperature (MAT) Sensor.

    dave w

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    8746 is a good ecm. I would stay with it, especially if you already have a stock calibration for it. Other than MAT I believe the ecm is plug n play with the 7747 harness.

    I helped a friend build a neat little 305 for a B body years ago. The build included 9C1 injectors, LT1 exhaust, 1.6 rockers, and a blocked coolant crossover under the TB. There was a surprising amount of power available for the limited amount of change, and it worked with the 8746. The engine was eventually transplanted to a truck that originally came with a V6. We installed the ecm IIRC with a minimum of wiring changes.

  8. #8
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    The 9C1s had swirl ports on them throughout the TBI years. The 350s had flat top pistons and L98 cams though. The non 9C1 cars ran the 305 peanut roller cam.

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    I guess the engine specs differ depending on where they are posted. :). I may have read on wikipedia that the heads and cam were L98's. Either that or I will blame a senior moment. I do have the flat top pistons. Going to measure the cam lobes when I get the chance. Hopefully tonight.

    Quote Originally Posted by Fast355 View Post
    The 9C1s had swirl ports on them throughout the TBI years. The 350s had flat top pistons and L98 cams though. The non 9C1 cars ran the 305 peanut roller cam.

  10. #10
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    Going through the settings in TunerPro. There sure aren't very many tables compared to the 7747 $42 bin's. It looks so much more simple.

    Quote Originally Posted by dave w View Post
    Here is the gearhead link to the '8746 information: http://www.gearhead-efi.com/Fuel-Inj...Information-61

    I like that the '8746 uses a Manifold Air Temperature (MAT) Sensor.

    dave w

  11. #11
    Super Moderator dave w's Avatar
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    Quote Originally Posted by srgould41 View Post
    Going through the settings in TunerPro. There sure aren't very many tables compared to the 7747 $42 bin's. It looks so much more simple.
    The processor performance '7747 vs. '8746 is about equal, or identical. The amount of time spent developing the '7747 .xdf is EXTENSIVE vs. the time spend developing the '8746 .xdf file. It's very likely all the tables available in the '7747 are also available in the '8746 but the .xdf has not been developed as EXTENSIVELY to show all the '8746 tables available.

    dave w

  12. #12
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    Thanks Dave.

    One thing i didn't find yet is if there is an equivalent 7747 bin to the ANLU. Any chance there is?

    To answer your earlier post.

    Injectors are part number 17084327

    I am a neophyte at using a micrometer so these are only accurate to a few ten thousandths.

    Cam lift
    Intake .2807
    Exh .2833

    Valve lift with 1.5 rockers
    Int .421
    Exh .425

    I need to look closer and see if there is a part number anywhere on the cam. Seems like an L98 cam to me.


    Everything points to it being a cop motor. Yay for me.

    Quote Originally Posted by dave w View Post
    The processor performance '7747 vs. '8746 is about equal, or identical. The amount of time spent developing the '7747 .xdf is EXTENSIVE vs. the time spend developing the '8746 .xdf file. It's very likely all the tables available in the '7747 are also available in the '8746 but the .xdf has not been developed as EXTENSIVELY to show all the '8746 tables available.

    dave w

  13. #13
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    Quote Originally Posted by srgould41 View Post
    I guess the engine specs differ depending on where they are posted. :). I may have read on wikipedia that the heads and cam were L98's. Either that or I will blame a senior moment. I do have the flat top pistons. Going to measure the cam lobes when I get the chance. Hopefully tonight.
    The confusion probably comes from the 87 and 88 Q-jet carb engines which DID use the centerbolt valve cover TPI L98 heads. The LG4s of the same era as well as the L69s in the Monte Carlo SS also used 395 TPI heads.

    The GM 300 hp crate engines used the same L98 heads that were cast for Marine engines. 217 ending of the casting number and the same cam that currently comes in the 330 hp Vortec 350 crate engine. Played with one of those 300 hp engines in a Elcamino SS that had the Chevelle front clip on it. With 1 3/4" primary ling tubes, 2 1/2" dual exhaust with a X-pipe, a performer rpm intake and an edelbrock 1406 I jetted up a bit to deal with the 10% ethanol gas it ran very strong.

    A factory OBD1 LT1 cam is a mild upgrade to the L98 cam. It has a little more lift and duration and a slightly tighter LSA. Makes a little more torque and carries the power a few hundred rpm higher. I LOVE us8ng them in Vortec trucks. The factory LT4 cam would be better still woth 1.6:1 rockers but they are rare as hens teeth now.
    Last edited by Fast355; 1 Week Ago at 04:53 PM.

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