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  1. #1
    Fuel Injected!
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    low BLM

    Hey guys, I need help with the truck running rich. It's a 95 with a 7427, L31r create motor, lun20080660 cam, spr 220 tbi ported 46mm, Harris chip w/upgrade fuel pump, headers to 3 inch single exhaust w/ 3 wire 02 sensor and EGR deleted. It has a 18lb spring in regulator and I've ordered a 14lb spring to use if needed. The injectors spray in the cone pattern with no dripping. I have no other problems, just bad gas mileage and strong exhaust smell. here is a data log at idle that might have codes set because I had tested sensors and didn't clear. Thanks, and let me know if I need to log data in a certain way
    Attached Files Attached Files

  2. #2
    Fuel Injected!
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    Quote Originally Posted by dhworkin View Post
    Hey guys, I need help with the truck running rich. It's a 95 with a 7427, L31r create motor, lun20080660 cam, spr 220 tbi ported 46mm, Harris chip w/upgrade fuel pump, headers to 3 inch single exhaust w/ 3 wire 02 sensor and EGR deleted. It has a 18lb spring in regulator and I've ordered a 14lb spring to use if needed. The injectors spray in the cone pattern with no dripping. I have no other problems, just bad gas mileage and strong exhaust smell. here is a data log at idle that might have codes set because I had tested sensors and didn't clear. Thanks, and let me know if I need to log data in a certain way
    Throw the Harris chip in the garbage can and start over with a stock file for your truck.

    If you are running without a cat that cam will always have a slight fuel smell to it around idle.

    Assuming you are running the stock 61 lb/hr 350 injectors the 18 psi spring, much less the 14 psi spring is low. Going to need more like 22-24 psi to support the 350-375 HP that engine is capable of.

    You need to get a performance oriented Vortec spark map like the one I have posted numerous times on here in the timing maps. From there you need to up the fuel pressure to atleast 22 psi. Set your injector flow constant to match the new flow rate. From there you will need to dial in the VE table.
    Last edited by Fast355; 01-02-2019 at 08:39 PM.

  3. #3
    Fuel Injected! PlayingWithTBI's Avatar
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    I have a similar setup in my '88 C1500 except instead of L31r I went with Summit Racing 162108 TBI aluminum heads 62cc with 2.02 intake and 1.60 exhaust, same TB with 18LB spring, heated O2, headers with JBA Y to 3" high flow cat and 3 chamber muffler. I also have a Harris chip, I think he calls it a level 4 on my 7747 ECU. I'm now working with Dave w on a new tune. I'll let you know how it comes out.

    I'm curious, do you know what bin file Harris used on yours? He called mine "...Summit 350 asdu L4".

  4. #4
    Fuel Injected!
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    Thanks Fast355, I tried to find your posts about the vortec spark map and the timing maps but not finding. I'll get on a better pc and learn to navigate this site. I started a little over a year ago after a guy on hotrodders sent me here. Dave W started to help me but I had to stop and deal with other things. He got me going with a ostrich 2 and I understand the data log, uploading and emulating process. I'm going to solder new connectors to sensors/switches this weekend and will do the work to regulator. Should I get the bolt/screw and modify the reg? and if so should I use 18lb spring? Pic is 02 after a 30 mile trip.
    PlayingWithTBI, he called the chip vortec. It had stage c level 1 on it.IMG_5473.JPG

  5. #5
    Fuel Injected!
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    I'm going to install a areomotive 13301 regulator. What I understand is that you block off the reg on the TB, flow is from pump to 13301 and out to fuel inlet on TB, run return line from 13301 to tank. What happens to the return line at TB, does it get plugged?

  6. #6
    Electronic Ignition!
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    dhworkin I feel your pain. I too have a Vortec engine with Edelbrock performer intake, tbi and headers. I also purchased a chip from Harris and my engine idles rich with a catalytic converter. I have tried fuel pressure up to 20 psi and down to 15 psi with no difference in behavior, so unfortunately, we both may need to start over with a decent tune before going in circles. Best of luck.
    Owl

  7. #7
    Electronic Ignition!
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    Quote Originally Posted by dhworkin View Post
    I'm going to install a areomotive 13301 regulator. What I understand is that you block off the reg on the TB, flow is from pump to 13301 and out to fuel inlet on TB, run return line from 13301 to tank. What happens to the return line at TB, does it get plugged?
    On ebay somebody makes a nice chromed block off plate for the tbi. Comes woth plate, screws and gasket. I think i paid somewhere between 10-20 bucks for it. Works perfect. And i bought a cheap aeromotive knockoff off ebay and put a aeromotive diaphragm in it. With it after the return line. All AN lines. Works flawlessly. Im running about 35 PSI of FP.

  8. #8
    Fuel Injected!
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    Quote Originally Posted by Fast355 View Post
    Throw the Harris chip in the garbage can and start over with a stock file for your truck.

    If you are running without a cat that cam will always have a slight fuel smell to it around idle.

    Assuming you are running the stock 61 lb/hr 350 injectors the 18 psi spring, much less the 14 psi spring is low. Going to need more like 22-24 psi to support the 350-375 HP that engine is capable of.

    You need to get a performance oriented Vortec spark map like the one I have posted numerous times on here in the timing maps. From there you need to up the fuel pressure to atleast 22 psi. Set your injector flow constant to match the new flow rate. From there you will need to dial in the VE table.
    Have you set your NEW injector flow constant? You need to do this first and can calculate it bottom of page here: https://www.witchhunter.com/injectorcalc1.php

    What are you doing to the VE tables that made it move from 90 to 105? Don't get me wrong...I want you to dumb it down so I know you know what you're doing.

  9. #9
    Fuel Injected!
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    Thanks for helping me with the injector calculator. I left the constant at 61 pph bc I didn’t know that it had to be changed. You want to make sure that I know what I’m doing, the obvious answer is (not really). So with 350 hp the calculator says 109 pph, does that mean that I should change the constant to 109? I input 12 for old and 22 for new fp and I got a new flow rate of 24, what should I do with that calculation? Thanks for the help, I am enjoying the process.

  10. #10
    Fuel Injected!
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    My PCM has provision for a scalar to set the "Injector Flow Rate (TBI lb/hr)", I just input the new calculated value there.
    This is not the most technical explanation but I've found if you just increased the fuel pressure you would be way rich, you can manually edit the VE table to compensate for the increased fuel flow (reduce the values) or in my case I can just change the Injector flow rate and seems to have a similar effect.
    Attached Images Attached Images

  11. #11
    Fuel Injected!
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    With my 8626 PCM the Injector flow rate value is also used for the TunerPro MPG calculations.

  12. #12
    Fuel Injected! donf's Avatar
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    Quote Originally Posted by Kitch View Post
    My PCM has provision for a scalar to set the "Injector Flow Rate (TBI lb/hr)", I just input the new calculated value there.
    This is not the most technical explanation but I've found if you just increased the fuel pressure you would be way rich, you can manually edit the VE table to compensate for the increased fuel flow (reduce the values) or in my case I can just change the Injector flow rate and seems to have a similar effect.
    $OD Bin has this too and I learned if you over or under estimate it you can end up with some really impressive or unimpressive VE% depending on what way you go. A lot of other ecms have the same thing. On another board some hot head was bragging that his VE% was way over normal, he got schooled by the other members. There are spread sheets here that help you figure out the proper numbers. The best way is to have the injectors cleaned and tested at a particular pressure.

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