[Gmecm] Soliciting Advice

[Rick McLeod]

I don't know what you mean by heavily modified, but I believe I am running a similar setup in my Camaro:
  L98 355CI SBC
  35# Ford injectors
  Crane Compu-cam 2032
  Crane Rollers 1.6:1
  Edlebrock TES headers
  Stock CAT
  3" FlowMaster AmericanThunder exhaust
Fuel Pressure @ 40#
  Bosch single wire O2 sensor
  Stock Bosch MAF
  160 stat
  xxx165 ECM
   
  and for this engine I was in a crunch so had SuperChips of Longwood, FL do the chip, appears they hit spot on the first cut, as it runs closed loop just fine, it will run on 87 fuel, is happy on 89, and screams on 91. Occaisionally on a hot day (90s +) if I romp on the loud pedal she'll ping on the lower octanes, so always run the good stuff summer time. I've got 'bout 30K on this build now, and don't think I could tweak much more by tunning on the chip, delivers somewhere around 30mpg cruising 75MPH @ about 2250RPM.
   
  So, I think you can get there, I'd not go lower on the pressure, IMHO a poor spray pattern would be worse, that could easily cause a poor burn. Make sure you're regulator is modulating correctly w/ vacuum, so you get higher pressure when needed. From what I recall when building mine the recommended bottom pressure for the F-injectors was 35 to 40. The other thing is make sure you've got good fire, I've found standard plugs in copper seem to work great.
   
  Hope this give you some confidence, I'd like to know more 'bout your setup.
   
  -rick
  
Mike Poore <mp at FlowersByValerie.com> wrote:
  Now that my heated O2 sensor is allowing me to collect closed loop data, 
I am trying to figure out what changes I should make.

I am working on a heavily modified L98 engine with the 1226870 ecm using 
a MAF. The injectors are too big, but I need to make use of them because 
of my budget.

Here are the data I collected at 1000 rpm:

BLM: 108
Integrator: 122-128
Inj. PW: .9ms
IAC: 58
Fuel Pressure: 35#
O2 Transitions are rapid and numerous

The BLM is at the bottom range, so I guess I need to lean it out. I am 
worried about lowering the fuel pressure and preventing good 
atomization. It seems that the injector pulse width can't be much lower.

When I link with Diacom, or any scanner for that matter, the engine goes 
into a mode where the spark is advanced and the idle is increased. Can 
this ecm be configured so that it operates the same when linked as it 
does when not linked?

How low can I go on the Ford fuel injectors and still get them to spray?

What's a normal injector pw at idle and what can I get away with?

With this heated O2 sensor, whats a safe warm-up delay before closed loop?

In addition to the above questions, I am throwing this out there for any 
advice.

Mike
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