Hi, I'm (starting) to use TunerPro so I can hopefully get my very rebuilt '87 454 TBI motor to run.

(For those interested: Edelbrock Mutlipoint injector intake, ally heads, roller rockers, 202/210@50 cam, 9.5:1 compression)

I'm taking my current prom (from the Edelbrock multi-point intake conversion) as the starting point. It ran with 8x19lb/hr injectors, which I'm changing for 29lb/hr ones, to support the expected 450hp.

So as a simple starting point, I'd like to alter the fuel tables to at least be aware of the bigger injectors, in the low rpms and idle, so it doesn't overfuel.

The thing is, I can't see an injector constant anywhere in the TunerPro lists, am I missing it? I imported 7747-mine.ecu defintion downloaded from the TunerPro site and saved it as 42.xdf. Am I missing the constant, or should I just alter the VE / fuel tables directly if there is no alterable constant?

Many thanks.

 

BPW in the constants will do the trick.

 

Thanks for the reply gofast, there's a 'BPW Const for EGF off' constant listed, but not just BPW (Base Pulse Width?) on its own. Is this is it, or something else?

 

I downloaded another 42.xdf file. I have the same setup except for the engine size. That xdf has been modified so might not be a good place to start. If I can find the file again I will post it for you. My 42.xdf file has the BPW (base pulse width in the constants.)

 

Well there is one for EGR off and a table for EGR on. It is for sure included in this XDF definition file.

 

Thanks guys. Fast355, that xdf sure us different to the one I already had! I guess the stock 7747 ecu file from the tunerpro site isn't so good? Where have you and gofast got your definitions from? (Or have you worked on them yourselves, I've got a lot to learn!!)

Thanks

 

I usually get mine from Craig Moates site. I am about to try dissasembling a Vortec PCM on my own though.

 

I found the file on a web site that I got from reading alot in this forum. There is a wealth of info and very helpful people here. Fast 355 has alot of posts and reading his stuff has been very helpful to me.

 

I know what you mean! I've been reading and reading for about 3 months now, but I'm almost at the point where I've got to try to put all this into practice. I pulled the my motor for a full rebuild, which is nearing completion. I've been looking at all this chip stuff in parallel since I realised that at the very least I would have to change the injectors for bigger units to realise the extra horsepower the rebuild is trying to achieve, and therefore the fuel tables at least would need tweaking. (And of course then spark due to engine changes).

Interesting, I've used the new XDF to look at the stock prom the engine originally had (ACLP), and the GM updrage AZFT. They both have BPWs of 134. I ran the truck like that for a year, and then installed the Edelbrock multipoint (which I ran for a few more years). That has a BPW of 187.

That sorta makes sense as the Edelbrock conversion certainly gave a kick in the guts, but ...

Stock 454 injectors (80 lbs/hr ??) x 2 = 160lbs/hr, and
Edlbrock 19lbs/hr x 8 = 152 lbs/hr ... less!!!?!?

I know the Edelbrock runs at much higher psi (45) compared to TBI (12), but the lbs/hr ratings should cover that. Maybe something to do with injecting into the intake ports rather than intake equates to a better flow?? Hmm, confused!!

Any thoughts?

Cheers

 

I think the math may be off a bit. read the come in for a free tune thread it has alot of the calculations that you need. The bigger the BPW the longer the pulse width of the injector. You can get a high enough pulse width that your injectors will go static(on all the time) at a very low rpm. 187 bpw for a 454 sounds way too high. I'll bet if you were to calculate it out from scratch that you will be down in the low 120's. You will need to estimate your horspower of your new setup then calculte what fuel pressure you will need based on the injectors you are using. Then you will be able to calculate a good bpw to start with.

 

Thanks, I'll take another look in that thread to check my calcs. I'm aiming for 450hp which is why I'm going to use 8x29lbs/hr injectors in the rebuild.

I think I may not have explained myself properly though, I'm just starting to look at burning chips now for when the rebuild is complete, I haven'y burnt any yet. The 134 BPW is what I *read* from the stock truck ACLP chip, and the 187 BPW was read from the Edelbrock chip currently in my truck from their conversion kit. Seems a bit weird?

 

I hear what you are saying! If you do the calcs on the stock stuff alot of times they are different than what is in the chip. It keeps you from obtaining any rpm as the injector constant is so high that your injectors will go static at maybe 3200-3600 rpm. Raising the fuel pressure and lowering the constant will give you some room in your rpm range.

 

Well there's the odd thing. I followed the maths in the Tune thread, and they are spot on for the stock GM ACLP and AZFT tunes, using 454cu and 80lb injectors, the result is the 134 as found in the chips.

I'm a little confised by the equations in the tune thread though, they reference the volume of a single cylinder, and what I assume is one injector (80lbs/hr) out of the two in a TBI setup. The edelbrock setup has 8 injectors at 19lbs/hr. Should that be multiplied by 4 to pretend to be one TBI injector?

Maybe the Edelbrock setup is just a bit weird. I'm tempted to use AZFT as my starting point for my own bin.

 

7.4/8=.925= volume of one cylinder. 4x19/3600x453.6=9.57 rate of injectors.BPW is 1461.5x .925/9.57=141. 29lb per hr. injectors will support 397 hp. so you would have to raise the fuel pressure on your 29's and recalculate to support your estimated 450hp.

 

Multipling the flow of a single injector by 4 (19 * 4) as 1 TBI injector for the calc is correct.

If you start pover with a stock '747 BIN reduce the AE by a lot. A port setup doesn't required as much AE as a wet-flow TBI setup. Can check the Edel BIN to see what kind of values they used.

When you increase the injector flow will also need to further reduce the AE. The AE calculations are PW based.

RBob.

 

Yorshire, edited my calcs based on rbob's explanation. As you can see it is very different than what is in your multipoint bin. This is what I was trying to show you. Thank you rbob for your correction.

 

Is there a chance there will be a tunerpro based program to read and flash the vortec style pcms? If so that would be awesome

 

That is what I am working for. Just have too many other projects to really sit down and try it. I am making an ECM test bench for the Vortec PCM as well, time permiting. In all truthfulness, I should just repin the harness, go to the silver PCM, and buy LS1 edit.

 

EFILive supports the 12200411 PCM already. S10Wildside is using it, and Lextech I believe has re-pinned his 97 L13 harness for the new PCM. I'm looking into changing my TCII for EFILive.
It's supposed to have an autotune feature.
I don't know enough about it yet to know for sure though.
Ron

 

The problem with equations of course is that everybody has different ones! Edelbrock explicitly claim in their literature

http://www.edelbrock.com/automotive_...8-123(efi).pdf

that their 29lb/hr injectors (x 8) are good for 450hp! I've gone with this claim, we'll see what I get!!

Cheers for the help so far anyway guys.