CFI Build Update...

[KANE]

Some four months and 28 different parameters changed later...


My average time to 60mph from a "rolling start" (~5 to 8 mph) on the factory 2.87 rear gear is between 5.9 and 6.2 seconds. And I have the datalogs to prove it.




I am really, really enjoying it- it's a real surprise to folks as the car looks totally stock.


Summary for those of you haven't seen the list of mods- here they are again:

• Dynamic EFI EBL Flash
• Dynamic EFI TT-1 Wideband O2 sensor
• TJ11 injectors
• Cast iron GM heads
• Erson .465" in / .488" ex cam, 224/234, 110 LSA
• Dynamic Crossfire Solutions Renegade intake
• GM Marine pressure regulator modified into VAFRP
• 15psi at idle / 20psi off idle (set between the two injectors pods, per GM)
• 775 idle speed
• Runs closed loop idle as well as closed loop during regular operation
• ~12.4 AFR during PE
• 5,300rpm WOT shift out of first gear
• Still runs the factory airbox- but modified to conceal an IAT sensor
• 9.1 compression

Not running the injectors parallel at this point... seems to idle just fine (for me) as well as come off idle to 2k rpm and beyond. Also, with a VAFPR hidden under the airbox on the injector pod, it keeps it looking stock.




Quick thanks to x-xfire, RF Master, Ronny, ...and especially RBob.

 

[KANE]

And it has been a learning experience... here's a smattering of what I learned along the way and what I went through.



DCS Renegade Intake
The 2nd run of Renegade intakes are really nice looking pieces- and they fit like true bolt-ons. The only thing that I'd tell you about them is to just go out and buy enough gasket material to make a lid-to-base gasket for the perimeter of the lid. DCS said use a gasket making material, but if you get a wide enough swath of good, gasket paper you can make one yourself instead of using something else.


Wiring
I took the plunge and re-pinned & re-crimped the harness to use the late-model connectors and NOT a HAM board. If you do this... save yourself the time and trouble and BUY A GM DELPHI TERMINAL CRIMPER! Your run-of-the-mill crimpers will not make the crimp small enough to fit inside the connectors. You'll end up just mangling the terminals and warping the combs.


Cam
Yeah, I only have 110 LSA. Not typically an EFI application for this cam. But the EBL with the amount of variables helps make up for the overlap. Does take a little playing with the VE and the AFR at low rpms to get to a good balance- but totally doable.


VE tables, and bad connections on a WB sensor
Wow- that drove me nuts! I set the VE table using the NB and then attempted to use the WB to dial in the values for PE. For the longest time, I thought I had a leaking exhaust system. Nope- turned out the wideband wasn't coming out of warm up due to a bad connector. It was connected well enough to kinda work... but not well. Yeah, that totally messed up my VE tables as it kept adding VE in small amounts to non-PE and 12 at a time to PE. For a while, I started to really question whether I would get the tune nailed down with all of the problems with the WB as I thought my 32 year old exhaust system must have had more holes than swiss cheese.


VAFPR
This took me a long time to decide. I really wanted to keep it looking stock and didn't want an aftermarket piece to draw attention to things. I did finally find a modified GM marine pressure regulator that would work as a VAFPR for me. It needed to have one of the bolt ears removed to fit the CFI injector tower- but otherwise fit perfectly. I'm running the hose to through the airbox using the thermostatic air solenoid's holes through the airbox.


Timing
I originally started with a TBI truck's SA table. Why? They are fairly close to other iron GM pre-86 heads. I found for me the truck SA tables were totally off- but thought it might be a decent start considering the heads are iron and were pretty much retired when TBI started to take off.

When I switched to an '85 Vette's SA table- things really started coming together. I am running about 32 degrees advance for 100kpa with about 3.5 for PE from 2800 to 6k rpm based upon convos with my engine builder (he runs max advance at 36 degrees under load). I can't overstate the importance of running the right SA table for the heads- I also can't overstate that if someone is using pre-86 iron heads on a Vette... they would likely benefit from the 85 Vette SA tables and NOT TBI truck tables.


Fuel Pump and Setting Fuel Pressure
Yes- MANY FOLKS have swapped their CFI's pump for a TPI pump. What I will tell you is the actual terminals- not the connector- are the same. There is no cutting required if your harness is good! Grab a safety pin and depress the tabs- and then back the terminals out of the housing. Slide them into the new, correct connector and it's an easy swap.

The fuel pressure is determined using a gauge set between the TBs. Easy enough... just make a temporary using the OEM line, high pressure line, high pressure clamps, and a gauge. For what it is worth... my OEM line seemed difficult to get a good seal. A great fix was to convert it to a braided line so that it can flex a little as it is tightened down.




One thing I want to be completely clear about- is that I am learning more and more every day and I am very gracious for the help and advice many have given me.

I'm sure I'll think of more things- but here is a start.


Sharing with any of you who might be interested in a personal account of what can be done with a CFI.

 

[Tom1]

Fuel Pressure Adjustment

Kane, I read your post with interest and can see you are making a lot of progress.

I am also learning a lot about the CFI system. I am interested in knowing how you would adjust the fuel pressure if it was needed. I understand there is an adjustment on the fuel pressure regulator but you have to take it apart to make this adjustment. I am referring to a 1984 Corvette. Thanks for any help.

Tom

 

[KANE]

Kane, I read your post with interest and can see you are making a lot of progress.

I am also learning a lot about the CFI system. I am interested in knowing how you would adjust the fuel pressure if it was needed. I understand there is an adjustment on the fuel pressure regulator but you have to take it apart to make this adjustment. I am referring to a 1984 Corvette. Thanks for any help.

Tom

Thanks!

Which reminds me... time to post an update. I'll get to that in a little while.

But the regulator- that's an easy mod. You'll need to remove the driver's side injector assembly with the pressure regulator. Then, take the four screws out of the pressure regulator housing. Then knock out (or drill out) the anti-tamper plug. Replace the diaphragm and then reassemble.

To adjust the pressure, you will need to have a gauge that sits in the transfer line between the front and rear TBIs. GM set the pressure at around 13 to 13.5 I believe. What makes it a PITA is the OE adjustment screw is basically a flat blade.

 

[KANE]

So... I've adjusted a total of 50 different tables, sclars, and flags from a factory BIN file.

TBI units
Oh- and added larger bore TB units. I'm at a little under 2" now (1.92").

Governor
I dialed in the 1-2 shift and the 2-3 shift. Using a B&M purple spring and an orange spring on factory weights, I have a 5,400rpm 1-2 shift and a 5,000rpm 2-3 shift. I spent most of last fall swapping springs and weights, but now it shifts the 1-2 just after making maximum horsepower.

Closed Loop
This took a LOT of fooling with. I basically adjusted the idle milivolts for the O2 sensor's lean, mean, and rich settings until I got an AFR of 14.0-14.8 for idle and then 14.2-14.9 for the integrator for cruising around. I'm in the 600s for all of those... factory TBI was in the 400s and 500s and I am just a bit richer than settings for an L98 Vette.

Air Cleaner Assembly & Fresh Air Chamber
I removed the flap and now the OE airbox draws air exclusively from the fresh air chamber. I also machined a block off plate into the thermostatic air snorkel and shut the flap closed to keep from pulling hot air in.

IAT/CTS Blend Filter & IAT location
I'm running about 39% towards the CTS at 16 Gm/Sec through 11.37% at 224 Gm/Sec. This seems to be a good balance when using the fresh air chamber. I had originally out the IAT in the air box, but it was prone to heat soak was pulling too much fuel out. The IAT is now just behind the headlight actuators in the path of incoming air that would slide along the underside of the hood and into the fresh air chamber.

Open Loop - AFR Multiplier vs CTS
It seems the intake design makes the tune want to run a little more fuel when the oil isn't completely warmed up and the temperature of the coolant is less than 180*. I believe that when cooler, the intake runs a little more dense air and is more prone to shearing fuel off the runners & intake walls. Adjusting the multiplier to -20% at 44* C up to -2.34 at the 80* C has kept the BLM and INT fairly steady as does the O2 milivolt settings.