The same???

my ecm ends in 6965

SO what file do I need to start with?

 

ohh sorry, I thought all the caprice's got the 746, Tuner cat has your ecm it uses the $62 mask. Their software cost money, but it's complete and the only place to get odd ball ecm's. You may be able to swap to the 746 with some minor repining of the ecm harness. I really don't know the specifics so you'll have to do some research.

start here: www.tunercat.com

 

I hear where you are coming from caddilac

Ive changed alot in my opinion on the subject.

I think most people and most applications are better off going carb for the fuel side of the house.

You can spend a few years reading and learning about DIY prom'ing and there are still things that are going to pop up and demand tons of time and resources to figure out.

Take for instance my swap back to TBI a few months ago. I could get it running GREAT, everywhere, EXCEPT at 4500-5000+ rpms, this is tuning with a wideband o2 which for me has never failed me in tuning my carb, its how ive almost kissed 105 mph with a 305 in the 1/4 mile. Im not a total idiot when it comes to proms either ive been reading about diy proms since late 98 (you can check the gmecm archives and see my first posts)

What happens when you run into a situation like this? Youve got more than enough fuel but any AFR (as indicated by the wb) you choose the car runs crappy at high rpm.

I dedicate more time to my cars than most people and really, by that point i was starting to dedicate way too much time to it without any progress. I guess I could go full on lab mode and set up some crazy 8 egt sensor setup and figure out whats going on but look at all that I invested to get there, it really starts to not be cost effective at all especially when carbs are proven and rediculously easy to tune.

I wish tbi would have worked for me its like the ultimate double pumper but alas i dont have a lifetime and a lab to figure it out.

This is mostly a rant about TBI diy prom'ing, with say for instance my buick, its been a proven performer by thousands with the basically stock electronics and the mods are easy and well documented. I still have not seen a legitimate fast TBI car running N/A . The only thing close that ive seen have alot of cubes and short cams. I wonder why.

 

I have to agree at least in part. While the tbi concept is fine, the statagies used by the stock ecm are simply pathetic by performance standards. The stock code is very limited in what it can do due to some of the constraints imposed by the ecms hardware. There isnt much control over the fueling above 3200 rpm and the resolution of the tables are somewhat coarse. Its much more suited to low revving engines, which is why most people choose that route when using tbi.

 

Pablo: i posted this on another thread. but when swapped in the larger cam and WB02 same day i found my 12.5/1(determined on dyno WB) and commanded at 12/1 went to 13.5/1 on my WB and commanded at 12.5/1. i reset commanded to 12/1 and ran 13.3/1 on WB. 350 cid and FP at 12 both times. will up FP to 15 and revisit PE WOT this spring. are you suggetsing TBI cannot fuel adequately at high RPM's? if so is it a limitation due to RPMs but not HP related(larger cid ie 383-lower rpms)?

 

This is exactly why I took a gamble with the new chip. I figured that it was possible someone had learned how to improve the stock PROM to allow a stock motor a little more performance.

 

What Dimented brought up doesn't touch on the chip itself. It is with the comptuer system. TBIChips, DIY, Hypertech, etc, we are all working within the bounds of the stock chip.

Speedreader, and the $60 code, can't come quick enough!!!!

(BTW, anyone heard any new info on that?)

 

If you missed it, this was the latest update.
. . . waiting . . .patiently waiting.

 

Quote..This is mostly a rant about TBI diy prom'ing, with say for instance my buick, its been a proven performer by thousands with the basically stock electronics and the mods are easy and well documented. I still have not seen a legitimate fast TBI car running N/A . The only thing close that ive seen have alot of cubes and short cams. I wonder why.


__________________
this was my Q. maybe someone with more knowledge can explain why the TBI fails at higher rpms? i suspect Holley has a spec on cid limitations/ hp limitations and maybe rpm limits? would 4 injectors help? or is holley ECU able to handle the load better than a GM? pablo said 4500-5000 rpms was an issue? my old cam ran 5000-5100 rpms on WB dyno at 12.3 or so commanded to 12/1 so fueling was not an issue(80 lbs @ 12 lbs) for me. but my new cam is a diff story?

 

Pablo didn't have issues with enough fuel, just with not performing well with the TBI on his car. Fueling is an issue with high HP motors. The problem is that you only have so much time to inject all the fuel you need. With only 2 injectors and the firing strategy used by the ecm it's tricky but not the end all. All of this is not a problem until your making 350 to 400 hp. The speed reader with Rbob's ultimate code will fix alot of the problems with high HP TBI setups.

 

I wasnt running out of fuel

the car just ran crappy at high rpm, engine hit a sour note and just didnt pull

 

It could very well be something with resonance in the plenum pushing the fuel back up out of the plenum. If it only happened for a few cylinders the other ones would run rich and it wouldn't show with the WB. Ever pull any plugs Pablo?

 

Quote: The problem is that you only have so much time to inject all the fuel you need.

Monte: please explain.

we are injecting fuel into a common plenum. right? as you know that plenum feeds the runners etc. a dual plane which i have is a bit different but practically the same. why is time an issue? is the dual TBI inadequate to keep the plenum saturated with atomized fuel and is exhausted of fuel resulting in a lean condition at high rpms? i is that why TPI with 8 injectors can keep up with fuel needs whereas we are limited to 90x2 or 180 lbs? maybe i am reading some thing into Pablo's statement that he did not state. the high rpm's.
Quote: the car just ran crappy at high rpm, engine hit a sour note and just didnt pull.

I would like to know why? is his car over 350 HP?

 

180pph of fuel, equites to 8 22.5pph injectors. Not even as large as the stock 350 injectors. Thus the problem.

 

Are you able to datalog? I've got an LO5 as well, but as stated before, I can't even datalog. I'm not computer literate.

 

I couldn't get my tbi to run smoothly @ 5000rpm +. Tried fueling, and spark changes countless times.

Now I've got a new 750cfm performer on the shelf, just waiting for spring. ECM to still run all the other stuff.

 

On the note of DIY equipment, craig moates sells a cheap burner for around $70. Bundle that with a datalog cable for $10 and your set. Just stick with free/cheap programmers.

Gunny, i actually havent datalogged for myself yet, because im still trying to assemble the pieces for burning. I do have winaldl and a cable on the way, so if i can get this going myself maybe i could pass on the knowledge to you. Im in alpharetta to be exact, so not sure how far away i am from you. I travel to savannah a lot for school so maybe that would be closer?

 

Savannah is closer to me than Easley.

I'd like to be able to burn my own, and since I am not building a high HP motor, I think I can learn.

Even if I have to pay someone to actually do the tuning side, I would want to be able to have them email the changes to me so I don't have to wait long periods.

 

Actually, I live in Kennesaw. I have all of the equipment, minus the actual stuff to burn, and all of the programs, but I haven't been able to get this crap to work for the life of me.

 

Ronnie, My point was that Pablo's problem doesn't have to do with the high rpm fueling problem, he had plenty of fuel. What ever was going wrong with his setup was something wierd, could be TBI related maybe not. Like Dewey said with only two injectors it gets to be hard to inject all the fuel needed in the allotted time which is around 5ms at 6000 rpm. Correct me if I'm wrong guys but the tbi fires the injectors once per engine revolution and the TPI does so once every two engine revs so they can hold their 8 injectors open longer with less off time. It's been a while since I looked at my notes, so that description may have some holes in it. I'd do some searches on PW and see what you come up with.

 

TBI alternates injectors on each plug firing. On a V8 each injector fires twice per revolution (4 cylinders fire per revolution).

TPI systems in double fire mode (normal fueling mode) fire all 8 injectors together each revolution (double firing per compression stroke). Once the PW falls below a set value (too short), they revert to a single fire mode. This is all 8 injectors once every two revolutions (single fire per compression stroke). Once the PW falls too short for single fire mode they are shut off ($8D code).

The key to more fuel with TBI units is to increase the fuel pressure. It also helps to get the largest injectors possible. This has several benefits: able to run lower fuel pressure which in turn reduces the injector opening time, and increases the fuel pump capacity.

I have run 350 injectors (Org/Blk) at 30 psi and 454 injectors (DrkBlu/DrkRed) at 22 psi with good results.

RBob.

 

Thats the kind of explanation you needed.

I'm running BBC injectors at 22 psi with good results.

 

I ran the "90" lb injectors at 20 psi and could easily drown the motor to 6000 rpm, down to low 11s afr on the WB

but like lowc1500 it wouldnt run smooth past 45-5000 rpm, i could feel it smooth out and make power at a couple of spots past that but it was definately sour.

I still wonder what caused it, Im glad to hear im not the only one that had that problem. Must be some something funny going on

 

i get to play with mine this spring. 80 lbs at 11 lbs currently and previously. i intend to up FP several times change the BPW constant, address VE/AE and take notes(log). i assume FP inadequate at 5800 but was adequate previously at 5000. i have not run car much since the TB/manifold/cam swap as cold weather hit. after i feel confident tune is close will run on dyno down the block and compare data from prior run with small cam vs larger cam. hope i can fuel it with no issues on top/ i dont expect any variable on TB/manifold swap as will be WOT.