May need a chip burned for 87 LO3 with 14097395 cam

[dave w]

I tune TBI systems with TunerPro RT. http://www.tunerpro.net/downloadApp.htm

Have you thought about burning your own chips? Maybe this post http://www.gearhead-efi.com/Fuel-Inj...sion-(27SF512) will help you with some of the technical details for converting your current computer to a flash chip you can burn yourself with a Moates.net Burn 2 http://www.moates.net/burn2-chip-programmer-p-197.html

dave w

[studboltgkw]

dave w . . . thanks for your reply. I was considering doing just that, but I definitely need to spend some time on how to do it. What I was hoping to do was upgrade the heads with a roller cam that the ecm "liked" so it would be drivable while I learned how to burn a chip to "fine tune" the combination. I wouldn't know how to burn a chip just to get it running again. I was hoping it would run with the LO3 bin file . . . that way if I mess up, I could always reload the LO3 parameters to return the truck to operational.

I thought maybe someone had burned a chip for this combo, and I would be willing to purchase a chip just to get it running. Then I was going to data log while driving to try my hand at improving fuel efficiency, etc.

Last night I was thinking that If I can't get it running with the 14097395 cam, I can pull it out and install a different roller cam that the LO3 ecm "liked".

Any additional thoughts? Would the TBI ECM work better with the '96-up L30 or L31 Vortec cam with the 112 LSA?

[dave w]

The challenge to tuning any non-stock cam (with or without modified heads) is figuring out a timing table that works. The next step is adjusting the fuel table for rich / lean driving conditions.

The chips I have are for 350's, 383's, and 454's. Maybe someone else has a 305 chip that can help you.

dave w

[studboltgkw]

dave w,
How difficult is it to tune a chip from scratch? I know a number of people on this blog hasn't had good luck with Harris Performance, Inc (tbichips.com) . . . there are other companies . . . Sinister Performance, LLC (gmtuners.com), Fastchip, etc.? Any recommendations?

I sure appreciate you help.

[dave w]

I tune my own chips, so I can't comment on other tuning companies.

Basically, tuning from scratch is not difficult if you have a good timing table from the get go. Most tuner use knock counts to adjust spark advance. My own personal experience has shown me that sometimes adding spark advance reduces spark knock. Adjusting the timing table is mostly trial and error. Adjusting the fuel table is more of a science using the Block Learn Multiplier (BLM) to correct fueling. BLM numbers above 128 are lean, and BLM number below 128 are rich.

When possible, I tune using a Wide Band Oxygen Sensor (WBO2). See attached screen shot of tuning with actual Air Fuel Ratios (AFR's). The only way to adjust Power Enrichment (PE) is with a WBO2.

dave w

[Fast355]

dave w . . . thanks for your reply. I was considering doing just that, but I definitely need to spend some time on how to do it. What I was hoping to do was upgrade the heads with a roller cam that the ecm "liked" so it would be drivable while I learned how to burn a chip to "fine tune" the combination. I wouldn't know how to burn a chip just to get it running again. I was hoping it would run with the LO3 bin file . . . that way if I mess up, I could always reload the LO3 parameters to return the truck to operational.

I thought maybe someone had burned a chip for this combo, and I would be willing to purchase a chip just to get it running. Then I was going to data log while driving to try my hand at improving fuel efficiency, etc.

Last night I was thinking that If I can't get it running with the 14097395 cam, I can pull it out and install a different roller cam that the LO3 ecm "liked".

Any additional thoughts? Would the TBI ECM work better with the '96-up L30 or L31 Vortec cam with the 112 LSA?

Knowing that cam and the vacuum signal it generates you should not be having the issue you describe. I would check the CTS, CTS connector and wiring and verify, clean and tighten all the grounds including the ground strap. Also verify you have a good TBI base gasket and the MAP sensor vacuum is connected to the correct port with no vacuum leaks. Cheat on the base timing a bit. Don't be afraid to advance the timing 6-8° over stock. I ran a 204/214 @ .050 on a 112° LSA and 1.6:1 rockers with ported 081 TPI heads on a stock L03 tune and while it did not run perfect it was perfectly driveable. You may also want to check the valve adjustment. If your valves are too tight it will reduce the vacuum and run poorly.

[Fast355]

One other thing you can do is drill into the minimum idle air rate screw cover on the throttle body and remove it. Behind the sealed cover is a Torx screw. You jumper the ALDL like you are reading codes and turn the key on but do not start. You will hear the IAC clicking. Wait about 30 seconds and unplug the IAC with the key on. I turn the key off, open the screw about 3 turns. Then start the truck. It will idle about 850 rpm. You can then bring the idle speed down to about 700 rpm. Shut off the engine and reconnect the IAC. The engine will now idle at no less than 700 rpm. Higher rpm = more vacuum and leaner mixture.

[1project2many]

I agree that the HT383 cam should provide a good vacuum signal. Is there any chance you were given 5.7 injectors instead of 5.0 injectors? Or that you've turned fuel pressure up? Check coolant temp reading vs actual coolant temp? Are you running an EGR valve?

Solus is usually considered a professional level tool. Just out of curiosity, are you a tech?

[studboltgkw]

dave w, Fast355, and 1project2many . . . my sincere thanks. Here's an update.

I went back to make sure that I had cleared all the possible mechanical issues. I took the valve covers off and back off the 1/2 turn on the rockers to 1/4 turn . . . thinking maybe that I had the valve lash too tight and was keeping a valve or two slightly open. You nailed this one, Fast355. I also pulled the new iridium plugs and installed a conventional set of AC Delco copper plugs to make sure I wasn't missing a cylinder causing it to idle rough and run rich.

Now, it's idling and all cylinders are firing!! Still running rich, but idling. the IAC is moving in an out causing the idle to "search". So, I jumpered pins A and B at the ALDL connector to get the IAC to close and then disconnected it. Turn the switch off and removed the jumper. I then started the truck and held the idle to 750 rpm with the accelerator pedal. I was measuring via the MAP sensor around 18" or so vacuum. Looks like I will have to remove the sealed cover and set a new idle as you indicated Fast355. I will follow-up with that effort. Hopefully, that will calm down the IAC.

I measured the resistance on the new coolant temp sensor and compared the temp read with the Solus Pro. It is matching the specs that I found at this site - http://www.chevytalk.org/fusionbb/sh...hp?tid/176155/

I am measuring around 900 and above at the O2 sensor when idling causing the Block Learn to be around 108 at idle and still returning Code 45. I measured the fuel pressure. Fuel pressure is reading at 14.5 psi with the stock spring and regulator (I replaced the diaphragm when I rebuilt the TBI unit). The injectors are the gm 40lb/hr injectors, part # 5235279. I am running a new AC Delco EGR valve.

Will the 305 with the ramjet cam run rich at idle, Fast355? Should I get an adjustable fuel pressure regulator and lower fuel pressure? Now that it is idling and running . . . can I data log for burning a better chip? Now, after it returns Code 45, it goes back and stays in Open Loop. Can you data log in Open Loop?

I purchased the Solus Pro used. Version 12.2. I like it a lot. It came with all the connectors for OBD I and OBD II.

Thanks, guys. Learning a lot here.

[studboltgkw]

Also, I have found out that there is a Marine Electronic Fuel Injection (MEFI) 305 with the ramjet cam. I could probably start there for a baseline chip. What do you think?