I finally got the thing running, but its running really rich. Origionally it was set for 18lb injectors, cc/cyl set to equal 383 total ci (don't remember what the # was) from the stock AUJP bin, just to be safe. It ran real rich on breakin, so I went back and changed the constant to a high 19 (19# from the LB9), and it still runs too rich. I went and grabbed the part #s off of the injectors (thinking the privious owner might have changed them out), but all I've been able to find on them is that they are made by Bosch. Bosch didn't make the stock injectors, did they? More info on that in this post: https://www.thirdgen.org/techbb2/sho...hreadid=294916

Anyway, I don't have an AFPR, so I'm guessing my only means of changing this condition is in the bin, but I'm not sure what else I can do until I get the ALDL cable. I don't have datalogging means at the moment, but I do have access to a wideband o2 sensor. I might grab that tonight and check it out, depending on if I can borrow it or not. What is the effect that it has on the AFR to raise the injector constant by one point? I'm not sure if its safe or not to go that route, or if there's something easier that I can do.

Oh yeah, the ecm is a '730 with $8D.

 

for Injector Constant :-)

 

If I hadn't already done a search for a definite answer then I wouldn't have asked. I just don't know if adjusting it is a valid way to try and regain the stoich ratio.

If there is another thread with this information then I'd be glad to look at it, but I don't see one with my answers in any search. Sorry if I'm overlooking it.

 

Injector constant is an inverse term or 1/lb/hr. So a bigger injector has a smaller constant.
This means that when you put a bigger injector in, the number in the bin file gets smaller. The actual number used in the ecm for multiplication.
You went smaller injector and gave the engine more fuel.

This is a partial explaination of the 8D fuel calc.
And some other good reading too.
8D PW

Might want to read the stickies a few times.
The info builds on itself. So as your understanding grows you'll catch things you missed on the previous read throughs.
Or things you simply forgot.

Don't understand why your other thread was locked

 

I understand. I just wasn't too sure if the practice of using a different constant for another injector size was acceptable or not.
I can see I have a lot of reading ahead of me too, go me!

And I don't understand either. Something about not actually asking the question until the second reply or something. I'm just glad I got it running. I tore it down to find out that I really did miss those plugs under the cam chain. Plugged em up and the oil pressure is off the gauge now.

 

Get the logger working! You need to see what is going on.
One tool alone could lead you in circles. Get the logging working so you can see just how rich you are and make changes then. When I first started mine, I had the same kind of condition (just fewer cubes) because my fuel pressure was at 50 and I didn't know it.
I just burned several bins with 19# to 30# and did quick startups and idling with each until I found a spot that began to work well.
I was using a 25# when it came around to being close. After getting "another" tool and checking the pressure I saw why this was happening. My 22's were actually like 26 at this pressure.
Try to use ALL of the tools available to move twards the result.
Take a good loooong read in the stickies on tuning 730, There is alot of info there and it will take reading it several times to BEGIN to sink in. there is a learning curve. Trying to get things done too quickly will only set you back farther.
Start by
1.) insuring the mechanicals are preset correctly (IAC, TPS),
2.)MAP, MAT, IAT are all reading within range,
3.) Initial advance set and confirmed (changed in bin to match)
4.) now get it to start and idle (will take some tries to get the richness out by Inj changes but you'll get there)
5.) Run through some logging at low rpm and loads and dial in the lower VE ranges.
6.) maybe play with spark a little here (maybe not if it seems ok)
7.) go back and tune more VE and adjust tables.
8.) maybe now start to look at the off idle stumbles and bogs if they exist.
Then you have a pretty stable base to beging going after the upper VE and WOT stuff with the WB.
THEN...
It will probably be time to begin the process again and do it right
If you were able to get just the above items exactly correct, you'd be the first in existence I think

This is not a perfect explaination by any means, I'm just letting you know how I have been approaching the process. Others may do it different, but it is a process and it takes time.

Ps,
I still give most credit for getting things done to the beer!

 

I'm not sure if its safe or not to go that route,....or if there's something easier that I can do.
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No, Hon, it won't be easy tuning up your speed density system (8D). There won't be any quick fixes that will be worth it. Get your cable, get a data logger and editor, read all the information available and then ask questions. Changing the injector constant or fuel pressure is a band-aid fix. You'll need less fuel at idle and more at WOT.

I feel your pain but nothing good ever comes easy. Do the work, avoid the pain...

 

Not really, some try to get by with doing that, and swear by it, but, making a universal change and then having to tune the rest of the table, anyway, just doesn't make sense to me.

Both are multipliers, and depending on how you twist things, by improperly changing numbers, will change the rounding errors, and possibly trash the final outcome to some degree.

It's MUCH, MUCH, easier to learn the good habits first, before trying to experiment.

 

I understand, and I plan on doing that as soon as I get the chance. I was just concerned, because it was running so rich that I was getting fuel in the oil, and I wouldn't be able to run it long enough to datalog anything without washing some bearings. Also, I need to grab an AFPR for the LT1 intake I'm getting, and I was just thinking that this might be a good temp fix to get it to run enough to break in the cam and rings, so that everything is good for the tuning.

Thanks guys.

 

The injector number you listed in the other post comes up as being from a 3.8l Buick engine. Don't have any other info. If the Buick engine was N/A they typically run about 18-19 #/hr. If they came from a boosted engine the injectors could be up around 26-28 #/hr (or more??).

RBob.

{edit: does the injector have the same color top as this one: http://www.witchhunter.com/FlowDataPix/b0280150235.jpg? 190cc isn't that large of an injector.}

 

[VE*MAP*displacement]
PW= ----------------------------------------
[#cyl*(IAT*CLT/2)*AFR*flowrate]

decrease your pulse width by increasing the injector flow rate (injector contant) but be careful at the upper rpms because it will probably be lean. I wouldn't think you'd want to do any break in until you have the fuel within trim range.