Subject: Re: tuning questions by djxib on 2013/5/10 17:43:18
Quote:
bam wrote: That's a healthy cam for a 350 (or is it a 383?). I would really like to have my wide band log with data master, could you give me more detail about the AC pressure switch, any place I could read up on how to do this, you wide band looks like mine - inovate? I have split BLM's all through the rpm/KPa bands, so if I want to correct VE tables by dividing the BLM recorded with 128 then use that as a multiplier which BLM do I use since they are split, or do I simply take the average of the two and use that? Say one is 140 the other 120 do I use 130 then? As for bucking, I call that steady cruise in lower rpm's (1000-1900 where you can't cruise w/o the car "bucking" like a mule. But even very slight acceleration of deceleration will immediately stop it. I have no hesitation when pulling away from a light either with WOT or part throttle. I think what you call cam surge is what I call bucking, it's exactly what I have below 1000 rpm which is really not a problem, the only time I drive that slow in first gear is pulling up the driveway. My throttle stop screw allows the blades to be completely closed, I have heard you want all the idle air to come thru the IAC, right?
Yes - fully built/forged 383.
For the A/C pressure signal approach - start here:
You'll need to look at the pinouts on your ECM to see what signal to switch.
OK so you have the classic cam surge associated with split BLMs. The problem with trying to average the BLMs across the split is that you'll end up in a less than ideal situation, but you could argue its not ideal anyway. Your next step will depend on what you want to do with the car.. let me give you a scenario:
You're staging at the drag strip and the BLMS are split - the ECM is pulling fuel one side and adding fuel on the other side. You hit WOT and the ECM will use the PE tables 'as-is' on the side it thinks is rich, but will add fuel to the PE values on the side it thinks is lean. This means that you potentially run rich down the 1/4 and post a slower time. Therefore a drag racer 'might' consider adjusting the VE table in the areas with worse split BLMs to be rich overall (i.e. therefore the ECM is pulling fuel both sides at idle and the PE tables are always used as-is). This makes the 1/4 performance more predictable.
Ultimately the choice is yours, I dont have a good recommendation for you other than:
1. Triple check everything and try all the tricks that other people have tried with the TB 2. or...Consider a band-aid with the VE table to 'protect' PE 3. or... Go open-loop
Like I say, I'm no expert in this so it would be good for some more opinions!
