What efi system is best for a 4.5 pfi cadillac engine7

[uncabob]

Some good info over at 3rdgen on spark latency for large cap HEI.

Bob

[S.O.B.B.]

Thanks Bob. I was reading on tgo about it last night.I kind of understand what it is but I don't see what reason for which setting is used on which distributor. I copied the whole latency table and burned that this morning. Could barely drive up the road.but like a dumb ass I changed more than one thing.I also copied the timing table for a corvette that I got off superchevy.so I'm gonna try the other latency table that I didn't try.that will be the 3rd table.I'm gonna try to get me a 2240 caddy ecm and read the chip so I can copy a few tables from that because I don't think any of the swirl port head setting work on this engine.it's more like a pre efi sbc engine.I do have most of the stock 4.5 engine specs so I can calculate things but my lack of experience here is making it a little difficult. I had originally started and ran this with a small cap grafted onto the top of the oe caddy distributor. But the phase was off.so I made it adjustable and put a hole in a old cap to get it set right.it had pretty much the same issue.so I switched to the caddy distributor and icm.it's different but feels like the small cap did when the phase was off.with the large cap I have no way to cut a hole to see where it's firing. Leaves me guessing till I get the read from a caddy chip.I'll keep trying.thanks

[S.O.B.B.]

Ok got some better results this last try for my drive to work.still says error beside prom but unsure of why.I played more with timing table.bpw at 148 the oe setting.ve table a bit.and this pic is the spark latency corretion I put in.Screenshot_2017-12-20-05-26-53.jpgI need to do more timing table work for lower rpm range.ad lots.blms are around 120 to 140 when on the gas but at cruise at 55mph blm at 160 plus.I notice my iac is 25 or so hot idle.145 key on engine off.but driving the number is around 80 until I take my foot off.I'm guessing that's letting lots of extra air in when unneeded and giving the lean condition.it's almost as though as tps and rpm rise so does iac. Is that setting of iac or faulty sign.anyone?20171220_210933.jpg20171220_205342.jpg20171220_210901.jpg

[dave w]

The attached $42 .xdl files are from reasonably good running engines.

dave w

[S.O.B.B.]

Thanks for the files Dave w.will try to get a look today.last night I downloaded 6870 1F (85 tpi) bin mostly because it's s large cap distributor. But the sa table uses load instead of map and I'm unsure of load numbers or if they compare to map numbers or if that just isn't something I can do. Looked at lots of other timing graphs and even the original from the 7747 asdm.I may try to put the large cap latency into that and start from there.not sure yet.after I get to see the files I'll go from there. Thanks

[S.O.B.B.]

Well I've been doing tuning almost daily and have reached a point where I can't get better blms. I did some reading and thought to double check what the injector numbers were.ah the importance of knowing what u have. I had a set from a 4.3 and they were indeed different numbers between the two.so I put a tbi 4.5 cadillac set in it.that was a vast improvement.I also put the spark plug gap from 45 I had it at to 60 the engine calls for.also found a cracked insulator on one plug so replaced it. But I'm still showing lean in the top and my ve table highest is 96.ve2 all set to 3.6 so total is never over 100.my bpw is at 153.my fuel pressure is 11psi rock steady.I'm looking for advice on what to do.I have a set of 5.0 injectors and wonder if I should try those and drop my bpw to 133 and scale back ve table and increase bpw from there as needed.in my $42 bin the injector bias is set at the factory .4ms.I have not changed that setting at all yet and wonder if I should be when large bpw changes occur.the factory bin bpw was 148.I've been as low as 133 and 153 the highest.blms at 30 kpa map are in range but once the map kpa rises above 30 I'm getting 130s 140s 150s on blm.any advice is much appreciated.

[stew86MCSS396]

From what I'm reading, are you "only" adjusting the BPW up and down to arrive at these blm results? I seem to recall a thread that tuning with BPW will tend to be rich for lower MAP values and lean for higher MAP values, so it's not a linear curve. If you have ve cells that are 96 and you're showing blms of 135ish, it's a safe bet the 5.0 injectors will do you good.

[S.O.B.B.]

Thanks Stew.I had globally lean.was trying ve table adjustment with each number I increased bpw.I just never had a bpw starting point since I have so much mismatched parts.the 148 stock setting I started with never worked because my timing was out due to spark latency being incorrect. So when I corrected it I never tried just starting over at 148 bpw.I'm at 153 now and running decent accept for a stumble I get if I don't roll on the the throttle.I also tried one burn with bpw at 154 and changed injector bias to .37 from .4.it didn't run well at all on that one.a lot more stumble. Once I get a nice day I plan to try the 5.0 injectors that I just gave an ultrasonic bath to.change bpw and see what I get.

[stew86MCSS396]

From what I'm reading, are you "only" adjusting the BPW up and down to arrive at these blm results? I seem to recall a thread that tuning with BPW will tend to be rich for lower MAP values and lean for higher MAP values, so it's not a linear curve. If you have ve cells that are 96 and you're showing blms of 135ish, it's a safe bet the 5.0 injectors will do you good.

Yes I'm quoting myself...you can adjust bpw up and down all day long. No matter which direction you go, lower MAP numbers will tend to be richer than higher MAP numbers. If you continue to tune this way, I think I would pursue 126-128 blms in the higher MAP numbers, then crunch the math for the rich idle/low MAP cells.

IIRC...EGR off is controlled by 3 scalars. Just download the latest xdf, apply the patch and be done with it.

[S.O.B.B.]

Thanks.I do have xdf that has the patches available. I just haven't had the time to fully read all the things the xdf I have doesn't. Been wanting to use the newest xdf but the names of some things being different from one to the other xdf kinda confused me.after checking location to verify it's the same setting I'm playing with I figure I should take the time to verify each item so I understand just what I change.the bpw I have left alone at 144 last 4 logs and been raising injector bias.went from .45 and now at .49.. and that's gotten it better so far than raising bpw.had been up to 153.but 144 is what the calculator comes up with.thanks for the help.it's very much. appreciated.