Just like the title says, I finally got the guts to modify my stock PROM. Just to play it safe, since I didn't have alot of time, all I changed was: fuel cutoff speed, Fan1 on/off temps, and injector flow rates.

I am running 22# injectors on my 305, and I changed it from the stock 19.8# to 21#.

Now my question is, at idle, INT goes to 150. I bumped up the fuel pressure some, but I din't bring the guage with me, but I got it down to 145, but under load, it goes down to around 128 +/- Is this something I did, or is going on? Or is this where VE table tweaking comes into play? I also noticed that at WOT, O2 mV is at 770mV, before changing it, it was 800+ What do I do now?


And another Q, I set the fan to come on @ 88*, and off @ 82, but with the scantool, it comes on at 91* and off at 81*, is there a reason for the descrepancy? I did verify Eprom to Buffer after programming and all was good.

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If you live in Southeastern US, check us out!
South East Thirdgen


ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey, 22# injectors,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
-->14.97 @ 94.9 MPH<--

'97 Bonneville SSE

[This message has been edited by GMTech (edited February 08, 2001).]

 

What program did you use to modify you bin? I too am using 22lb injectors on a 305 but using winbin to change injector size didnt help me.

 

Tuner Cat

------------------
If you live in Southeastern US, check us out!
South East Thirdgen


ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey, 22# injectors, Whatever chip I feel like burning,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
--&gt;14.97 @ 94.9 MPH&lt;--

'97 Bonneville SSE

 

GMTech,

I would be really interested to see what fuel pressure you are running. With 22# injectors and a constant of 21# you should start with your fuel pressure around 43-45. Are you sure you have 22# injectors? How do you know you have 22# injectors? The reason that I ask is because if you were running 22# injectors on a 305 WITHOUT a modified PROM then you should have been running VERY VERY rich.

Also - you didn't mention what your BLMs were at idle? Did you reset the computer after putting the new PROM in?

Tim

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• Program your own PROMs!. Read my article to get started!
• Research and Experiment before asking questions.
• This is not a chip store. Go to the classifieds if you want someone to sell you a chip or give you a BIN.

TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

I'm pretty sure they are 22's because I had the fellows at work cross reference the Part Numbers at work, and they are 1985 Corvette injectors, First Design. I beleive that, because they are still mounted to the Corvette style fuel rail on my car.

When I started it up in the morning w/ the stock prom, it would spew black smoke, and also when I "launched" it would also bellow black smoke. The other day, it finally spit out a code 45. I will check the fuel pressure tomarrow. It "was" at stock setting, I turned it a little tonight to try and get the fuel trim down.

With the scan tool, I reset the fuel trims to 128/128 (gotta love that!)

------------------
If you live in Southeastern US, check us out!
South East Thirdgen


ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey, 22# injectors, Whatever chip I feel like burning,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
--&gt;14.97 @ 94.9 MPH&lt;--

'97 Bonneville SSE

 

Glad to hear that you finally got your "toys" Bernard. I found that I was too rich basically through out the RPM/LOAD range except the lower kpa values, where I was a bit lean.

Before I set the fuel pressure to where I wanted it (initially I started my alternations to the VE tables with my fuel pressure at its lowest setting), I ended up with much flatter VE tables, with a little extra fuel needed at the lower kpa range.

When I then increased the fuel pressure, I noticed that it had its greatest effect at the high kpa range and hardly any effect on the lower kpa values. Again, flattened my VE tables.

Sounds like you are experiencing kind of the same thing I did. Start with you fuel pressure where you would like it (46-48 psi), then adjust your injector flow constant to where you tend to get the best sounding idle, and then adjust the higher kpa values as neccessary (but don't worry about 128 "perfect" just get all the values in the 120-130s range.

At that point, go hit the spark tables as the spark will affect the AF ratio; then go back and finish off the VE tables trying to get them closer to 128. As you get closer to 128, the "shape" of the table will define itself. I am STILL tweaking my VE tables; it gets kind of addictive after awhile.