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Thread: low BLM

  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
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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 10:39 AM.

  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
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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
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    I have found as long as you are looking for a fuel pressure higher than your tbi spring, just connect return from tbi to inlet of aeromotive and outlet to return line, you are good to go.
    6395, BHDF, 7.4 BBC lightly modded now 6395 BMHM back to BHDF

  8. #8
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    Quote Originally Posted by myburb View Post
    I have found as long as you are looking for a fuel pressure higher than your tbi spring, just connect return from tbi to inlet of aeromotive and outlet to return line, you are good to go.
    I remove the regulator completely and fabricate a cover to go into its place. It eliminates a possible future fuel leak from a ruptured diaphram.

  9. #9
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    I got rid of the Harris chip and loaded a stock bin, set up history table and smoothed VE. Got the 13301 installed(on the return side) thanks for the help. Going to make a block off plate and change header gaskets this weekend and would like to install a Wbo2 but I don't know what to get. what do you suggest, thanks

  10. #10
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    I found one reason its been rich, it was something to do with the coil location. I've been chasing this problem for over two years, bad idle, stalls, falls on its face, timing jumping around with wire disconnected, poor throttle response (stomp it to the floor and there's a 2 sec delay before acceleration) and a lot of other strange problems. The manifold is a Edelbrock performer EPS 2716 and I mounted the coil in the same factory location (behind the TBI) and never liked how it was so close to the distributor. So the other day I wrapped the coil with a piece of sheet rubber and it ran great, then I mounted the coil on the bracket that holds the MAP sensor and it's even better. I don't know what was going on with the coil but I'm glad those problems are gone and I can go into this tune as if it's a new build.

  11. #11
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    1995, 16197427 BJXL, L31r w/lunati 20080660. First question is, because of the cam, when I install the stock bin do I change initial spark advance to 9.8 or leave it at 0.

  12. #12
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    Quote Originally Posted by dhworkin View Post
    1995, 16197427 BJXL, L31r w/lunati 20080660. First question is, because of the cam, when I install the stock bin do I change initial spark advance to 9.8 or leave it at 0.
    Initial Spark Advance or Base Spark Advance matches your distributors physical setting. What I tend to do there is run as much initial as the combination will allow without kicking back on the starter hot. This generally gives the best cold start. 10-14* BTDC generally works out very well in my experience.

  13. #13
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    Fast355, you said you've posted a vortec spark map numerous times, I've looked but I cant find anything. I'm pretty sure I'm not going to be able to do this (not that I don't want to) and will need to pay to get it right. I can load bins, datalogging, built a history table for blm, smooth ve tables, downloaded and learned excel so I can use Dave w's work sheets but I cant find a timing table for my next step. I need this to happen a lot faster.

  14. #14
    Fuel Injected! dud's Avatar
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    Last edited by dud; 04-15-2019 at 10:23 AM.

  15. #15
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    Thanks dud. I tried to paste the spark table from excel to the bin, but it wouldn't bc I have a 600 and 1000 RPM columns in my bin and the vortec excel sheet doesn't . So I copied from 1200 to 6000 and pasted, copied the 400 column and pasted and then the 800. Next I filled in the 600 and 1000 RPM columns with the values close to the cells around them and was wondering if that is correct or should I build the table in my bin that don't have the 600 and 800 RPM columns.

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