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L31 TBI 746 ECM

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Old 07-09-2014, 09:10 PM
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Car: 1990 Camaro RS
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L31 TBI 746 ECM

If you want to read about my swap so far here is the thread:

https://www.thirdgen.org/forums/tbi/...-vortec-4.html

My set up is a DCtrumpet 46 mm throttle body base with New AC Delco 2172286 injectors for a 350. I have a LT4 hot cam, Alex's parts spring kit and a RPM Airgap intake with adapter. I am trying to build my initial start up bin. Fast355 recommended using the LT1 timing table so I have adapted that to my L03 bin here:

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I noticed the table only goes to 3600 rpm, does the timing stay the same above that?

Any suggestions what to start with for my fuel table? DCtrumpet told me to set the fuel pressure to 18-20 psi, anything I have to change in the bin to compensate for this?

I have been reading the stickies and using search, there is a lot of good info out there.

Last edited by Spaceboy1980; 07-24-2014 at 01:34 AM.
Old 07-10-2014, 09:34 AM
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Re: L31 TBI 746 ECM

Once over 3600 RPM the 3600 RPM row will be used.

With increased fuel pressure the injector offset and multiplier values typically need to be increased.

RBob.
Old 07-10-2014, 04:13 PM
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Re: L31 TBI 746 ECM

That is what I figured about the timing table. There isn't very much accuracy there, I guess it is a primitive ECM. Thanks for that info.

As for the offset, I understand what it is but I cannot locate where to adjust it in TunerPro. This is all above my head at the moment but I am digging in. Thanks again.
Old 07-10-2014, 04:41 PM
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Re: L31 TBI 746 ECM

The injector PW multiplier table is at $3E9
The injector offset (bias) is at $2DA

Can search the ECU/XDF in Tuner Pro via the address.

As for the table using the 3600 RPM row when over that, it is that way in all four table directions. Below 400 RPM uses the 400 row.

Same for the columns. The final value retrieved from the table is also interpolated between the row & columns.

RBob.
Old 07-10-2014, 09:07 PM
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Re: L31 TBI 746 ECM

I think I had the Fbody Lt1 spark table because I found one you had posted. I subbed it into my bin and it looks better than what I had.

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What is a good ballpark for the injector multiplier table and offset? Should I just leave it alone first then see what my BLMs are?
Old 07-14-2014, 10:15 AM
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Re: L31 TBI 746 ECM

Originally Posted by Spaceboy1980
I think I had the Fbody Lt1 spark table because I found one you had posted. I subbed it into my bin and it looks better than what I had.



What is a good ballpark for the injector multiplier table and offset? Should I just leave it alone first then see what my BLMs are?
Just swap the stock 350 cop car offests into it if you haven't already. Get it up and running and look at the VE table as you get them dialed in. If the lower RPM starts to bathtub, increase the offsets by a couple hundred usecs at a time until the VE table starts to look correct.
Old 07-14-2014, 02:09 PM
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Re: L31 TBI 746 ECM

Thanks guys!
Old 07-15-2014, 01:37 AM
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Re: L31 TBI 746 ECM

I used the timing table from this post of RBob's:

https://www.thirdgen.org/forums/post...606-post3.html

And the ANLU cop car bin injector PW table and offset and came up with this bin. I have hopefully deleted the EGR inside of it as well as functionally deleted the speed limiter.
Attached Files
File Type: zip
EGR Delete LT1 Timing v3.zip (3.6 KB, 71 views)
Old 07-23-2014, 04:23 AM
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Re: L31 TBI 746 ECM

Fast, what did you mean by bathtub?

With this ecm, is there anyway to datalog knock counts? I was able to make a history table for blm but when I try to make one for knock it isn't available in the drop down.

I have moved to the vortec timing table due to the car not liking part throttle tip in. Without being able to monitor knock I just feel like the lt1 table is too aggressive.
Old 07-23-2014, 09:11 AM
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Re: L31 TBI 746 ECM

The upper byte of the knock counter is in the data stream.

RBob.
Old 07-23-2014, 09:48 AM
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Re: L31 TBI 746 ECM

Does that mean it is missing from the adx?
Old 07-23-2014, 10:25 AM
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Re: L31 TBI 746 ECM

I don't know. IIRC, WinALDL provides history on knock.

RBob.
Old 07-23-2014, 10:29 AM
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Re: L31 TBI 746 ECM

I think I found it, I believe OLDPA3 to be knock. I made a table using it and it is filling. Thanks for taking time to help me out.
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